database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2026-10-23 13:29:09 +03:00
Code Activity

Fix deferred XLogLogicalInfo update after a failed transaction block.

Browse Source 
Previously, a backend with an assigned XID deferred the
XLogLogicalInfo update requested by a procsignal barrier, and we
applied it in AbortTransaction() on abort. However, a failed
transaction block keeps its XID until ROLLBACK, so a barrier absorbed
while idle in that state was deferred, and CleanupTransaction() did
not apply it. The next transaction then ran entirely with the stale
value. If logical decoding had just been enabled, that transaction's
changes were written without logical information and silently skipped
by decoding.

Fix by applying the pending update in CleanupTransaction() instead of
AbortTransaction(). We call it after resetting the top-level XID
because, unlike the commit and prepare paths, CleanupTransaction()
isn't always called with interrupts held, so a barrier absorbed before
the reset would be deferred again and carried into the next
transaction.

Patch by Sergei Patiakin, with tests added by me.

Oversight in commit 67c20979ce.

Reported-by: Sergei Patiakin <sergei.patiakin@enterprisedb.com>
Author: Sergei Patiakin <sergei.patiakin@enterprisedb.com>
Reviewed-by: Shlok Kyal <shlok.kyal.oss@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/CANE55rApeNAFaqxLWrvm-NC0Y5gkrBFZFVaHVYP89AGS2SYMcA@mail.gmail.com
Backpatch-through: 19
This commit is contained in:
Masahiko Sawada
2026-10-06 10:00:49 -07:00
parent 63e33d40b2
commit a80744949c
3 changed files with 46 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
src/backend/access/transam/xact.c
View File

@@ -3055,7 +3055,6 @@ AbortTransaction(void)
AtEOXact_PgStat(false, is_parallel_worker);
AtEOXact_ApplyLauncher(false);
AtEOXact_LogicalRepWorkers(false);
AtEOXact_LogicalCtl();
pgstat_report_xact_timestamp(0);
}
@@ -3108,6 +3107,17 @@ CleanupTransaction(void)
XactTopFullTransactionId = InvalidFullTransactionId;
nParallelCurrentXids = 0;
/*
* Apply any pending XLogLogicalInfo update. This must be done here
* rather than in AbortTransaction(), because a failed transaction block
* keeps its XID until ROLLBACK, so a barrier absorbed meanwhile is
* deferred. Unlike CommitTransaction() and PrepareTransaction(), we are
* not necessarily holding interrupts here, so do this after resetting the
* top-level XID; otherwise a barrier absorbed in between would be left
* pending into the next transaction.
*/
AtEOXact_LogicalCtl();
/*
* done with abort processing, set current transaction state back to
* default

6
src/backend/replication/logical/logicalctl.c
View File

@@ -227,7 +227,11 @@ IsXLogLogicalInfoEnabled(void)
}
/*
* Reset the local cache at end of the transaction.
* Apply a pending XLogLogicalInfo update at end of the top-level transaction.
*
* This is called from CommitTransaction(), PrepareTransaction(), and
* CleanupTransaction(), which are the only places where the top-level XID is
* reset, so the next transaction always starts with the latest value.
*/
void
AtEOXact_LogicalCtl(void)

30
src/test/recovery/t/051_effective_wal_level.pl
View File

@@ -78,6 +78,36 @@ wait_for_logical_decoding_disabled($primary);
test_wal_level($primary, "replica|replica",
"logical decoding disabled after repack");
# Test that a backend applies an XLogLogicalInfo update that it received
# while its transaction block was in the failed state, once the block ends.
# The failed transaction keeps its XID until ROLLBACK, so the update is
# deferred; it must not be carried over into the next transaction.
my $psql_aborted = $primary->background_psql('postgres', on_error_stop => 0);
$psql_aborted->query_safe(q[begin; select pg_current_xact_id();]);
my ($aborted_out, $aborted_ret) = $psql_aborted->query(q[select 1/0;]);
is($aborted_ret, 1, "transaction block failed");
$psql_aborted->{stderr} = '';
# Enable logical decoding while the backend is idle in the failed transaction
# block. This waits for all backends to absorb the barrier.
$primary->safe_psql('postgres',
qq[select pg_create_logical_replication_slot('test_aborted_slot', 'test_decoding')]
);
# Check the value in the transaction right after ROLLBACK. Note that both
# commands need to be sent together, as query_safe() appends an empty query
# that would run in its own transaction and apply the deferred update.
is( $psql_aborted->query_safe(
q[rollback; select current_setting('effective_wal_level');]),
'logical',
"effective_wal_level is updated after rolling back a failed transaction block"
);
$psql_aborted->quit;
$primary->safe_psql('postgres',
qq[select pg_drop_replication_slot('test_aborted_slot')]);
wait_for_logical_decoding_disabled($primary);
# Create a new logical slot and check that effective_wal_level must be increased
# to 'logical'.
$primary->safe_psql('postgres',