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help / color / mirror / Atom feedFrom: Hayato Kuroda (Fujitsu) <[email protected]>
To: 'Michael Paquier' <[email protected]>
To: [email protected] <[email protected]>
Cc: 'Paul A Jungwirth' <[email protected]>
Cc: Mutaamba Maasha <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: David G. Johnston <[email protected]>
Cc: Zhijie Hou (Fujitsu) <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: Bertrand Drouvot <[email protected]>
Subject: RE: ReplicationSlotRelease() crashes when the instance is in the single user mode
Date: Thu, 21 Aug 2025 06:39:47 +0000
Message-ID: <OSCPR01MB149668B67979F8F4C73B69E2EF532A@OSCPR01MB14966.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <[email protected]>
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Dear Michael and hackers,
This is a wrap-up of this thread. I'm planning to close the thread once.
> I am saying that there is little point in having tests for the origin
> functions in single-user mode as these don't do anything really
> fancy with global states (there's a acquired_by of course, and no
> specific IsUnderPostmaster patch), contrary to the replication slots.
> I am not convinced that there is any need to restrict them, either.
> If somebody shows a reason to justify such a move, we could argue
> about it, of course.
OK, thanks for the clarification. Yes, there are no special path for
single-user mode for origins.
Now, senior members recently appeared here are not so motivated to restrict some
operations in single-user mode unless it cannot be done in principle. Based on
that, I decided to close the thread once until someone raised another point.
For the reference purpose, I attached a patch which prohibits slot manipulation
in single-user mode. Anyone can update and use the patch for any purposes.
Best regards,
Hayato Kuroda
FUJITSU LIMITED
Attachments:
[application/octet-stream] v8-0001-Prohibit-slot-manipulation-while-in-single-user-m.patch (8.6K, ../OSCPR01MB149668B67979F8F4C73B69E2EF532A@OSCPR01MB14966.jpnprd01.prod.outlook.com/2-v8-0001-Prohibit-slot-manipulation-while-in-single-user-m.patch)
download | inline diff:
From 2e5c5aeab9eadcc386dec00e7f2c67bbaa900667 Mon Sep 17 00:00:00 2001
From: Hayato Kuroda <[email protected]>
Date: Wed, 19 Feb 2025 11:37:26 +0900
Subject: [PATCH v8] Prohibit slot manipulation while in single-user mode
Replication-related commands are rarely used in single-user mode and have been
broken for years. This commit prohibits calling slot manipulation SQL functions
to avoid additional risk of failures. One exception is pg_drop_replication_slot.
It is still allowed because users may want to clean up their mistakes in the mode.
---
doc/src/sgml/func/func-admin.sgml | 5 ++
.../replication/logical/logicalfuncs.c | 3 ++
src/backend/replication/slot.c | 12 +++++
src/backend/replication/slotfuncs.c | 14 +++++
src/backend/utils/adt/pg_upgrade_support.c | 3 ++
src/include/replication/slot.h | 1 +
.../test_misc/t/008_replslot_single_user.pl | 53 ++++++++++++++-----
7 files changed, 78 insertions(+), 13 deletions(-)
diff --git a/doc/src/sgml/func/func-admin.sgml b/doc/src/sgml/func/func-admin.sgml
index 6347fe60b0c..6363084bc94 100644
--- a/doc/src/sgml/func/func-admin.sgml
+++ b/doc/src/sgml/func/func-admin.sgml
@@ -1012,6 +1012,11 @@ postgres=# SELECT '0/0'::pg_lsn + pd.segment_number * ps.setting::int + :offset
are also relevant for replication.
</para>
+ <para>
+ Note that slot manipulation functions except <function>pg_drop_replication_slot</function>
+ cannot be used in single-user mode.
+ </para>
+
<table id="functions-replication-table">
<title>Replication Management Functions</title>
<tgroup cols="1">
diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index ca53caac2f2..30877fdc3ab 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -113,6 +113,9 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
List *options = NIL;
DecodingOutputState *p;
+ /* Slot manipulation is not allowed in single-user mode */
+ CheckSlotIsInSingleUserMode();
+
CheckSlotPermissions();
CheckLogicalDecodingRequirements();
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index fd0fdb96d42..4ca1227cc94 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -1529,6 +1529,18 @@ CheckSlotPermissions(void)
"REPLICATION")));
}
+/*
+ * Check whether the instance is in single-user mode.
+ */
+void
+CheckSlotIsInSingleUserMode(void)
+{
+ if (!IsUnderPostmaster)
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("replication slots cannot be used in single-user mode")));
+}
+
/*
* Reserve WAL for the currently active slot.
*
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 69f4c6157c5..90fe63283a1 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -17,6 +17,7 @@
#include "access/xlogrecovery.h"
#include "access/xlogutils.h"
#include "funcapi.h"
+#include "miscadmin.h"
#include "replication/logical.h"
#include "replication/slot.h"
#include "replication/slotsync.h"
@@ -76,6 +77,9 @@ pg_create_physical_replication_slot(PG_FUNCTION_ARGS)
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
+ /* Slot manipulation is not allowed in single-user mode */
+ CheckSlotIsInSingleUserMode();
+
CheckSlotPermissions();
CheckSlotRequirements();
@@ -182,6 +186,9 @@ pg_create_logical_replication_slot(PG_FUNCTION_ARGS)
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
+ /* Slot manipulation is not allowed in single-user mode */
+ CheckSlotIsInSingleUserMode();
+
CheckSlotPermissions();
CheckLogicalDecodingRequirements();
@@ -521,6 +528,9 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
Assert(!MyReplicationSlot);
+ /* Slot manipulation is not allowed in single-user mode */
+ CheckSlotIsInSingleUserMode();
+
CheckSlotPermissions();
if (XLogRecPtrIsInvalid(moveto))
@@ -618,9 +628,13 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot)
TupleDesc tupdesc;
HeapTuple tuple;
+
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
+ /* Slot manipulation is not allowed in single-user mode */
+ CheckSlotIsInSingleUserMode();
+
CheckSlotPermissions();
if (logical_slot)
diff --git a/src/backend/utils/adt/pg_upgrade_support.c b/src/backend/utils/adt/pg_upgrade_support.c
index a4f8b4faa90..337f705b34b 100644
--- a/src/backend/utils/adt/pg_upgrade_support.c
+++ b/src/backend/utils/adt/pg_upgrade_support.c
@@ -296,6 +296,9 @@ binary_upgrade_logical_slot_has_caught_up(PG_FUNCTION_ARGS)
*/
Assert(has_rolreplication(GetUserId()));
+ /* Slot manipulation is not allowed in single-user mode */
+ CheckSlotIsInSingleUserMode();
+
slot_name = PG_GETARG_NAME(0);
/* Acquire the given slot */
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
index e8fc342d1a9..b4d89760f96 100644
--- a/src/include/replication/slot.h
+++ b/src/include/replication/slot.h
@@ -342,6 +342,7 @@ extern void CheckPointReplicationSlots(bool is_shutdown);
extern void CheckSlotRequirements(void);
extern void CheckSlotPermissions(void);
+extern void CheckSlotIsInSingleUserMode(void);
extern ReplicationSlotInvalidationCause
GetSlotInvalidationCause(const char *cause_name);
extern const char *GetSlotInvalidationCauseName(ReplicationSlotInvalidationCause cause);
diff --git a/src/test/modules/test_misc/t/008_replslot_single_user.pl b/src/test/modules/test_misc/t/008_replslot_single_user.pl
index 796700d621f..4a93ed585d3 100644
--- a/src/test/modules/test_misc/t/008_replslot_single_user.pl
+++ b/src/test/modules/test_misc/t/008_replslot_single_user.pl
@@ -29,8 +29,30 @@ sub test_single_mode
],
'<' => \$queries);
+ return $result;
+}
+
+# Wrapper function for test_single_mode. This would be used when the input
+# command succeeds.
+sub test_single_mode_ok
+{
+ my ($node, $queries, $testname) = @_;
+
+ my $result = test_single_mode($node, $queries, $testname);
+
ok($result, $testname);
}
+
+# Wrapper function for test_single_mode. This would be used when the input
+# command fails.
+sub test_single_mode_fail
+{
+ my ($node, $queries, $testname) = @_;
+
+ my $result = test_single_mode($node, $queries, $testname);
+
+ ok(!$result, $testname);
+}
my $slot_logical = 'slot_logical';
my $slot_physical = 'slot_physical';
@@ -41,53 +63,58 @@ $node->init(allows_streaming => "logical");
$node->start;
# Define initial table
-$node->safe_psql('postgres', "CREATE TABLE foo (id int)");
+$node->safe_psql(
+ 'postgres', qq(
+CREATE TABLE foo (id int);
+SELECT pg_create_logical_replication_slot('$slot_logical', 'test_decoding');
+SELECT pg_create_physical_replication_slot('$slot_physical');
+));
$node->stop;
-test_single_mode(
+test_single_mode_fail(
$node,
- "SELECT pg_create_logical_replication_slot('$slot_logical', 'test_decoding')",
+ "SELECT pg_create_logical_replication_slot('another_slot', 'test_decoding')",
"logical slot creation");
-test_single_mode(
+test_single_mode_fail(
$node,
- "SELECT pg_create_physical_replication_slot('$slot_physical', true)",
+ "SELECT pg_create_physical_replication_slot('another_slot', true)",
"physical slot creation");
-test_single_mode(
+test_single_mode_fail(
$node,
"SELECT pg_create_physical_replication_slot('slot_tmp', true, true)",
"temporary physical slot creation");
-test_single_mode(
+test_single_mode_fail(
$node, qq(
INSERT INTO foo VALUES (1);
SELECT pg_logical_slot_get_changes('$slot_logical', NULL, NULL);
),
"logical decoding");
-test_single_mode(
+test_single_mode_fail(
$node,
"SELECT pg_replication_slot_advance('$slot_logical', pg_current_wal_lsn())",
"logical slot advance");
-test_single_mode(
+test_single_mode_fail(
$node,
"SELECT pg_replication_slot_advance('$slot_physical', pg_current_wal_lsn())",
"physical slot advance");
-test_single_mode(
+test_single_mode_fail(
$node,
"SELECT pg_copy_logical_replication_slot('$slot_logical', 'slot_log_copy')",
"logical slot copy");
-test_single_mode(
+test_single_mode_fail(
$node,
"SELECT pg_copy_physical_replication_slot('$slot_physical', 'slot_phy_copy')",
"physical slot copy");
-test_single_mode(
+test_single_mode_ok(
$node,
"SELECT pg_drop_replication_slot('$slot_logical')",
"logical slot drop");
-test_single_mode(
+test_single_mode_ok(
$node,
"SELECT pg_drop_replication_slot('$slot_physical')",
"physical slot drop");
--
2.47.1
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Subject: RE: ReplicationSlotRelease() crashes when the instance is in the single user mode
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