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authorMichael Paquier2018-07-10 23:56:24 +0000
committerMichael Paquier2018-07-10 23:56:24 +0000
commit56a714721343e6f52c0b1b911c0f160592348e84 (patch)
tree58344b8c0a3aa8cd5a570d7b55cae34cbfb922c8
parentb6e3a3a492dbf2043e4b149221007716ba9e364e (diff)
Block replication slot advance for these not yet reserving WAL
Such replication slots are physical slots freshly created without WAL being reserved, which is the default behavior, which have not been used yet as WAL consumption resources to retain WAL. This prevents advancing a slot to a position older than any WAL available, which could falsify calculations for WAL segment recycling. This also cleans up a bit the code, as ReplicationSlotRelease() would be called on ERROR, and improves error messages. Reported-by: Kyotaro Horiguchi Author: Michael Paquier Reviewed-by: Andres Freund, Álvaro Herrera, Kyotaro Horiguchi Discussion: https://postgr.es/m/[email protected]
-rw-r--r--contrib/test_decoding/expected/slot.out17
-rw-r--r--contrib/test_decoding/sql/slot.sql6
-rw-r--r--doc/src/sgml/catalogs.sgml3
-rw-r--r--src/backend/replication/slotfuncs.c13
4 files changed, 33 insertions, 6 deletions
diff --git a/contrib/test_decoding/expected/slot.out b/contrib/test_decoding/expected/slot.out
index 21e9d56f73..2737a8a301 100644
--- a/contrib/test_decoding/expected/slot.out
+++ b/contrib/test_decoding/expected/slot.out
@@ -131,3 +131,20 @@ SELECT pg_drop_replication_slot('regression_slot1');
ERROR: replication slot "regression_slot1" does not exist
SELECT pg_drop_replication_slot('regression_slot2');
ERROR: replication slot "regression_slot2" does not exist
+-- slot advance with physical slot, error with non-reserved slot
+SELECT slot_name FROM pg_create_physical_replication_slot('regression_slot3');
+ slot_name
+------------------
+ regression_slot3
+(1 row)
+
+SELECT pg_replication_slot_advance('regression_slot3', '0/0'); -- invalid LSN
+ERROR: invalid target wal lsn
+SELECT pg_replication_slot_advance('regression_slot3', '0/1'); -- error
+ERROR: cannot advance replication slot that has not previously reserved WAL
+SELECT pg_drop_replication_slot('regression_slot3');
+ pg_drop_replication_slot
+--------------------------
+
+(1 row)
+
diff --git a/contrib/test_decoding/sql/slot.sql b/contrib/test_decoding/sql/slot.sql
index 706340c1d8..24cdf7155d 100644
--- a/contrib/test_decoding/sql/slot.sql
+++ b/contrib/test_decoding/sql/slot.sql
@@ -68,3 +68,9 @@ SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot1', 'test_
-- both should error as they should be dropped on error
SELECT pg_drop_replication_slot('regression_slot1');
SELECT pg_drop_replication_slot('regression_slot2');
+
+-- slot advance with physical slot, error with non-reserved slot
+SELECT slot_name FROM pg_create_physical_replication_slot('regression_slot3');
+SELECT pg_replication_slot_advance('regression_slot3', '0/0'); -- invalid LSN
+SELECT pg_replication_slot_advance('regression_slot3', '0/1'); -- error
+SELECT pg_drop_replication_slot('regression_slot3');
diff --git a/doc/src/sgml/catalogs.sgml b/doc/src/sgml/catalogs.sgml
index 3ed9021c2f..4851bc2e24 100644
--- a/doc/src/sgml/catalogs.sgml
+++ b/doc/src/sgml/catalogs.sgml
@@ -9867,7 +9867,8 @@ SELECT * FROM pg_locks pl LEFT JOIN pg_prepared_xacts ppx
<entry></entry>
<entry>The address (<literal>LSN</literal>) of oldest WAL which still
might be required by the consumer of this slot and thus won't be
- automatically removed during checkpoints.
+ automatically removed during checkpoints. <literal>NULL</literal>
+ if the <literal>LSN</literal> of this slot has never been reserved.
</entry>
</row>
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 2806e1076c..23af32355b 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -483,6 +483,12 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
/* Acquire the slot so we "own" it */
ReplicationSlotAcquire(NameStr(*slotname), true);
+ /* A slot whose restart_lsn has never been reserved cannot be advanced */
+ if (XLogRecPtrIsInvalid(MyReplicationSlot->data.restart_lsn))
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("cannot advance replication slot that has not previously reserved WAL")));
+
/*
* Check if the slot is not moving backwards. Physical slots rely simply
* on restart_lsn as a minimum point, while logical slots have confirmed
@@ -495,14 +501,11 @@ pg_replication_slot_advance(PG_FUNCTION_ARGS)
minlsn = MyReplicationSlot->data.restart_lsn;
if (moveto < minlsn)
- {
- ReplicationSlotRelease();
ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot move slot to %X/%X, minimum is %X/%X",
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("cannot advance replication slot to %X/%X, minimum is %X/%X",
(uint32) (moveto >> 32), (uint32) moveto,
(uint32) (minlsn >> 32), (uint32) minlsn)));
- }
/* Do the actual slot update, depending on the slot type */
if (OidIsValid(MyReplicationSlot->data.database))