From 17f66a68179bfe91a57987ffafafa9063c3907c7 Mon Sep 17 00:00:00 2001 From: Masahiko Sawada Date: Wed, 21 Oct 2026 10:44:12 -0700 Subject: [PATCH] Reject COPY TO of unlogged tables during recovery. Unlogged tables have no data on a standby, so reading one there must fail. SELECT and COPY (SELECT ...) TO already report a clear error, but COPY with a table name read the table directly and failed with a low-level error instead: ERROR: could not open file "base/5/16384": No such file or directory Check for this case in COPY TO and report the same error as SELECT. On v19 and later, also check each partition when copying from a partitioned table, so that an unlogged partition is reported too. Backpatch to all supported versions, since the low-level error looks like data corruption. Author: Jim Jones Reviewed-by: Zsolt Parragi Reviewed-by: Masahiko Sawada Discussion: https://postgr.es/m/b6d71815-d362-4579-bf07-73eca01aee6d@uni-muenster.de Backpatch-through: 14 --- src/backend/commands/copyto.c | 5 +++++ src/test/recovery/t/001_stream_rep.pl | 13 +++++++++++++ 2 files changed, 18 insertions(+) diff --git a/src/backend/commands/copyto.c b/src/backend/commands/copyto.c index 84dc465cbae..a3e7cc12ba2 100644 --- a/src/backend/commands/copyto.c +++ b/src/backend/commands/copyto.c @@ -409,6 +409,11 @@ BeginCopyTo(ParseState *pstate, RelationGetRelationName(rel)))); } + /* Temporary and unlogged relations are inaccessible during recovery. */ + if (rel != NULL && !RelationIsPermanent(rel) && RecoveryInProgress()) + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot access temporary or unlogged relations during recovery"))); /* Allocate workspace and zero all fields */ cstate = (CopyToStateData *) palloc0(sizeof(CopyToStateData)); diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl index f3ea45ac4a2..c511918bba7 100644 --- a/src/test/recovery/t/001_stream_rep.pl +++ b/src/test/recovery/t/001_stream_rep.pl @@ -105,6 +105,19 @@ is( $node_standby_1->safe_psql( 't', 'pg_sequence_last_value() on unlogged sequence on standby 1'); +# Check that COPY TO rejects unlogged tables on standby +$node_primary->safe_psql( + 'postgres', q{ +CREATE UNLOGGED TABLE ultab (a int); +}); +$node_primary->wait_for_replay_catchup($node_standby_1); +my ($copy_ret, $copy_stdout, $copy_stderr) = + $node_standby_1->psql('postgres', 'COPY ultab TO STDOUT'); +like( + $copy_stderr, + qr/cannot access temporary or unlogged relations during recovery/, + 'COPY TO of unlogged table on standby 1'); + # Check that only READ-only queries can run on standbys is($node_standby_1->psql('postgres', 'INSERT INTO tab_int VALUES (1)'), 3, 'read-only queries on standby 1');