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help / color / mirror / Atom feedFrom: Álvaro Herrera <[email protected]>
Subject: [PATCH v49 7/7] WIP add max_repack_replication_slots
Date: Wed, 1 Apr 2026 19:54:14 +0200
---
src/backend/commands/repack_worker.c | 4 +-
src/backend/replication/logical/launcher.c | 2 +-
src/backend/replication/logical/slotsync.c | 5 +-
src/backend/replication/slot.c | 77 +++++++++++--------
src/backend/replication/slotfuncs.c | 8 +-
src/backend/replication/walsender.c | 4 +-
src/backend/utils/misc/guc_parameters.dat | 8 ++
src/backend/utils/misc/postgresql.conf.sample | 2 +
src/include/replication/slot.h | 6 +-
9 files changed, 74 insertions(+), 42 deletions(-)
diff --git a/src/backend/commands/repack_worker.c b/src/backend/commands/repack_worker.c
index 106b2b60441..00b21ede481 100644
--- a/src/backend/commands/repack_worker.c
+++ b/src/backend/commands/repack_worker.c
@@ -228,8 +228,8 @@ repack_setup_logical_decoding(Oid relid)
* RS_TEMPORARY so that the slot gets cleaned up on ERROR.
*/
snprintf(NameStr(slotname), NAMEDATALEN, "repack_%d", MyProcPid);
- ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, false,
- false);
+ ReplicationSlotCreate(NameStr(slotname), true, RS_TEMPORARY, false, true,
+ false, false);
EnsureLogicalDecodingEnabled();
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 09964198550..d83125afd0d 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -1575,7 +1575,7 @@ CreateConflictDetectionSlot(void)
errmsg("creating replication conflict detection slot"));
ReplicationSlotCreate(CONFLICT_DETECTION_SLOT, false, RS_PERSISTENT, false,
- false, false);
+ false, false, false);
init_conflict_slot_xmin();
}
diff --git a/src/backend/replication/logical/slotsync.c b/src/backend/replication/logical/slotsync.c
index e75db69e3f6..1bc7f3f600d 100644
--- a/src/backend/replication/logical/slotsync.c
+++ b/src/backend/replication/logical/slotsync.c
@@ -425,7 +425,7 @@ get_local_synced_slots(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -814,6 +814,7 @@ synchronize_one_slot(RemoteSlot *remote_slot, Oid remote_dbid,
*/
ReplicationSlotCreate(remote_slot->name, true, RS_TEMPORARY,
remote_slot->two_phase,
+ false,
remote_slot->failover,
true);
@@ -1691,7 +1692,7 @@ update_synced_slots_inactive_since(void)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index a9092fc2382..fe6bfeba25e 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -151,6 +151,9 @@ ReplicationSlot *MyReplicationSlot = NULL;
/* GUC variables */
int max_replication_slots = 10; /* the maximum number of replication
* slots */
+int max_repack_replication_slots = 1; /* the maximum number of slots
+ * for REPACK */
+int TotalMaxReplicationSlots = 0; /* sum of both */
/*
* Invalidate replication slots that have remained idle longer than this
@@ -190,12 +193,14 @@ ReplicationSlotsShmemSize(void)
{
Size size = 0;
- if (max_replication_slots == 0)
+ TotalMaxReplicationSlots = max_replication_slots + max_repack_replication_slots;
+
+ if (TotalMaxReplicationSlots == 0)
return size;
size = offsetof(ReplicationSlotCtlData, replication_slots);
size = add_size(size,
- mul_size(max_replication_slots, sizeof(ReplicationSlot)));
+ mul_size(TotalMaxReplicationSlots, sizeof(ReplicationSlot)));
return size;
}
@@ -208,7 +213,7 @@ ReplicationSlotsShmemInit(void)
{
bool found;
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return;
ReplicationSlotCtl = (ReplicationSlotCtlData *)
@@ -222,7 +227,7 @@ ReplicationSlotsShmemInit(void)
/* First time through, so initialize */
MemSet(ReplicationSlotCtl, 0, ReplicationSlotsShmemSize());
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[i];
@@ -372,6 +377,7 @@ IsSlotForConflictCheck(const char *name)
* db_specific: logical decoding is db specific; if the slot is going to
* be used for that pass true, otherwise false.
* two_phase: If enabled, allows decoding of prepared transactions.
+ * repack: If true, use a slot from the pool for REPACK.
* failover: If enabled, allows the slot to be synced to standbys so
* that logical replication can be resumed after failover.
* synced: True if the slot is synchronized from the primary server.
@@ -379,10 +385,11 @@ IsSlotForConflictCheck(const char *name)
void
ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover, bool synced)
+ bool two_phase, bool repack, bool failover, bool synced)
{
ReplicationSlot *slot = NULL;
- int i;
+ int startpoint,
+ endpoint;
Assert(MyReplicationSlot == NULL);
@@ -431,12 +438,16 @@ ReplicationSlotCreate(const char *name, bool db_specific,
LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
/*
- * Check for name collision, and identify an allocatable slot. We need to
- * hold ReplicationSlotControlLock in shared mode for this, so that nobody
- * else can change the in_use flags while we're looking at them.
+ * Check for name collision (across the whole array), and identify an
+ * allocatable slot (in the array slice specific to our current use case:
+ * either general, or REPACK only). We need to hold
+ * ReplicationSlotControlLock in shared mode for this, so that nobody else
+ * can change the in_use flags while we're looking at them.
*/
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ startpoint = repack ? max_replication_slots : 0;
+ endpoint = repack ? TotalMaxReplicationSlots : max_replication_slots;
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -444,7 +455,9 @@ ReplicationSlotCreate(const char *name, bool db_specific,
ereport(ERROR,
(errcode(ERRCODE_DUPLICATE_OBJECT),
errmsg("replication slot \"%s\" already exists", name)));
- if (!s->in_use && slot == NULL)
+
+ if (i >= startpoint && i < endpoint &&
+ !s->in_use && slot == NULL)
slot = s;
}
LWLockRelease(ReplicationSlotControlLock);
@@ -547,7 +560,7 @@ SearchNamedReplicationSlot(const char *name, bool need_lock)
if (need_lock)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -575,7 +588,7 @@ int
ReplicationSlotIndex(ReplicationSlot *slot)
{
Assert(slot >= ReplicationSlotCtl->replication_slots &&
- slot < ReplicationSlotCtl->replication_slots + max_replication_slots);
+ slot < ReplicationSlotCtl->replication_slots + TotalMaxReplicationSlots);
return slot - ReplicationSlotCtl->replication_slots;
}
@@ -869,7 +882,7 @@ ReplicationSlotCleanup(bool synced_only)
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
@@ -1251,7 +1264,7 @@ ReplicationSlotsComputeRequiredXmin(bool already_locked)
if (!already_locked)
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
TransactionId effective_xmin;
@@ -1306,7 +1319,7 @@ ReplicationSlotsComputeRequiredLSN(void)
Assert(ReplicationSlotCtl != NULL);
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
XLogRecPtr restart_lsn;
@@ -1373,12 +1386,12 @@ ReplicationSlotsComputeLogicalRestartLSN(void)
XLogRecPtr result = InvalidXLogRecPtr;
int i;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return InvalidXLogRecPtr;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
XLogRecPtr restart_lsn;
@@ -1453,11 +1466,11 @@ ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive)
*nslots = *nactive = 0;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
@@ -1514,13 +1527,13 @@ ReplicationSlotsDropDBSlots(Oid dboid)
bool found_valid_logicalslot;
bool dropped = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
char *slotname;
@@ -1617,11 +1630,11 @@ CheckLogicalSlotExists(void)
{
bool found = false;
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s;
bool invalidated;
@@ -1662,7 +1675,10 @@ CheckSlotRequirements(void)
* needs the same check.
*/
- if (max_replication_slots == 0)
+ /* FIXME how to relax this for repack in a way that doesn't mess everything
+ * up?
+ */
+ if (TotalMaxReplicationSlots == 0)
ereport(ERROR,
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
errmsg("replication slots can only be used if \"max_replication_slots\" > 0")));
@@ -2216,7 +2232,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
Assert(!(possible_causes & RS_INVAL_WAL_REMOVED) || oldestSegno > 0);
Assert(possible_causes != RS_INVAL_NONE);
- if (max_replication_slots == 0)
+ if (TotalMaxReplicationSlots == 0)
return invalidated;
XLogSegNoOffsetToRecPtr(oldestSegno, 0, wal_segment_size, oldestLSN);
@@ -2224,7 +2240,7 @@ InvalidateObsoleteReplicationSlots(uint32 possible_causes,
restart:
found_valid_logicalslot = false;
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
bool released_lock = false;
@@ -2329,7 +2345,7 @@ CheckPointReplicationSlots(bool is_shutdown)
*/
LWLockAcquire(ReplicationSlotAllocationLock, LW_SHARED);
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
char path[MAXPGPATH];
@@ -2430,7 +2446,7 @@ StartupReplicationSlots(void)
FreeDir(replication_dir);
/* currently no slots exist, we're done. */
- if (max_replication_slots <= 0)
+ if (TotalMaxReplicationSlots <= 0)
return;
/* Now that we have recovered all the data, compute replication xmin */
@@ -2860,7 +2876,7 @@ RestoreSlotFromDisk(const char *name)
errhint("Change \"wal_level\" to be \"replica\" or higher.")));
/* nothing can be active yet, don't lock anything */
- for (i = 0; i < max_replication_slots; i++)
+ for (i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *slot;
@@ -2902,6 +2918,7 @@ RestoreSlotFromDisk(const char *name)
break;
}
+ /* XXX might be misleading if the slots previously in use were REPACK. */
if (!restored)
ereport(FATAL,
(errmsg("too many replication slots active before shutdown"),
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 9f5e4f998fe..cdb4dbd87c9 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -53,7 +53,7 @@ create_physical_replication_slot(char *name, bool immediately_reserve,
/* acquire replication slot, this will check for conflicting names */
ReplicationSlotCreate(name, false,
temporary ? RS_TEMPORARY : RS_PERSISTENT, false,
- false, false);
+ false, false, false);
if (immediately_reserve)
{
@@ -146,7 +146,7 @@ create_logical_replication_slot(char *name, char *plugin,
*/
ReplicationSlotCreate(name, true,
temporary ? RS_TEMPORARY : RS_EPHEMERAL, two_phase,
- failover, false);
+ false, failover, false);
/*
* Ensure the logical decoding is enabled before initializing the logical
@@ -270,7 +270,7 @@ pg_get_replication_slots(PG_FUNCTION_ARGS)
currlsn = GetXLogWriteRecPtr();
LWLockAcquire(ReplicationSlotControlLock, LW_SHARED);
- for (slotno = 0; slotno < max_replication_slots; slotno++)
+ for (slotno = 0; slotno < TotalMaxReplicationSlots; slotno++)
{
ReplicationSlot *slot = &ReplicationSlotCtl->replication_slots[slotno];
ReplicationSlot slot_contents;
@@ -665,7 +665,7 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
* managed to create the new slot, we advance the new slot's restart_lsn
* to the source slot's updated restart_lsn the second time we lock it.
*/
- for (int i = 0; i < max_replication_slots; i++)
+ for (int i = 0; i < TotalMaxReplicationSlots; i++)
{
ReplicationSlot *s = &ReplicationSlotCtl->replication_slots[i];
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index fbbe09135bf..caea3ed1257 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1220,7 +1220,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
{
ReplicationSlotCreate(cmd->slotname, false,
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT,
- false, false, false);
+ false, false, false, false);
if (reserve_wal)
{
@@ -1251,7 +1251,7 @@ CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
*/
ReplicationSlotCreate(cmd->slotname, true,
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL,
- two_phase, failover, false);
+ two_phase, false, failover, false);
/*
* Do options check early so that we can bail before calling the
diff --git a/src/backend/utils/misc/guc_parameters.dat b/src/backend/utils/misc/guc_parameters.dat
index 0a862693fcd..d12a3bd7bdf 100644
--- a/src/backend/utils/misc/guc_parameters.dat
+++ b/src/backend/utils/misc/guc_parameters.dat
@@ -2070,6 +2070,14 @@
max => 'MAX_BACKENDS',
},
+{ name => 'max_repack_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
+ short_desc => 'Sets the maximum number of replication slots for use by REPACK.',
+ variable => 'max_repack_replication_slots',
+ boot_val => '1',
+ min => '0',
+ max => 'MAX_BACKENDS /* XXX? */',
+},
+
/* see max_wal_senders */
{ name => 'max_replication_slots', type => 'int', context => 'PGC_POSTMASTER', group => 'REPLICATION_SENDING',
short_desc => 'Sets the maximum number of simultaneously defined replication slots.',
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index cf15597385b..15014f37753 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -348,6 +348,8 @@
# (change requires restart)
#max_replication_slots = 10 # max number of replication slots
# (change requires restart)
+#max_repack_replication_slots = 1 # max number of replication slots for REPACK
+ # (change requires restart)
#wal_keep_size = 0 # in megabytes; 0 disables
#max_slot_wal_keep_size = -1 # in megabytes; -1 disables
#idle_replication_slot_timeout = 0 # in seconds; 0 disables
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index 4b4709f6e2c..88953576894 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -324,9 +324,13 @@ extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
/* GUCs */
extern PGDLLIMPORT int max_replication_slots;
+extern PGDLLIMPORT int max_repack_replication_slots;
extern PGDLLIMPORT char *synchronized_standby_slots;
extern PGDLLIMPORT int idle_replication_slot_timeout_secs;
+/* only for slotfuncs.c, slotsync.c etc */
+extern int TotalMaxReplicationSlots;
+
/* shmem initialization functions */
extern Size ReplicationSlotsShmemSize(void);
extern void ReplicationSlotsShmemInit(void);
@@ -334,7 +338,7 @@ extern void ReplicationSlotsShmemInit(void);
/* management of individual slots */
extern void ReplicationSlotCreate(const char *name, bool db_specific,
ReplicationSlotPersistency persistency,
- bool two_phase, bool failover,
+ bool two_phase, bool repack, bool failover,
bool synced);
extern void ReplicationSlotPersist(void);
extern void ReplicationSlotDrop(const char *name, bool nowait);
--
2.47.3
--3n3vqr5y2jhknrqj--
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