postgres.git / summary / log / commit / refs
commit 39d55557661f6d2fc0b5781b3f40390ca4febdad
Author: Nathan Bossart <nathan@postgresql.org>
Date: Fri Jan 09 16:12:54 2026 +0000
First released in: 18.2
pg_dump: Fix gathering of sequence information.
Since commit bd15b7db48, pg_dump uses pg_get_sequence_data() (née
pg_sequence_read_tuple()) to gather all sequence data in a single
query as opposed to a query per sequence. Two related bugs have
been identified:
* If the user lacks appropriate privileges on the sequence, pg_dump
generates a setval() command with garbage values instead of
failing as expected.
* pg_dump can fail due to a concurrently dropped sequence, even if
the dropped sequence's data isn't part of the dump.
This commit fixes the above issues by 1) teaching
pg_get_sequence_data() to return nulls instead of erroring for a
missing sequence and 2) teaching pg_dump to fail if it tries to
dump the data of a sequence for which pg_get_sequence_data()
returned nulls. Note that pg_dump may still fail due to a
concurrently dropped sequence, but it should now only do so when
the sequence data is part of the dump. This matches the behavior
before commit bd15b7db48.
Bug: #19365
Reported-by: Paveł Tyślacki <pavel.tyslacki@gmail.com>
Suggested-by: Tom Lane <tgl@sss.pgh.pa.us>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19365-6245240d8b926327%40postgresql.org
Discussion: https://postgr.es/m/2885944.1767029161%40sss.pgh.pa.us
Backpatch-through: 18
src/backend/commands/sequence.c | 14 ++++++++------
src/bin/pg_dump/pg_dump.c | 12 ++++++++++++
2 files changed, 20 insertions(+), 6 deletions(-)
diff --git a/src/backend/commands/sequence.c b/src/backend/commands/sequence.c
index 451ae6f7f69..a79ef0651a9 100644
--- a/src/backend/commands/sequence.c
+++ b/src/backend/commands/sequence.c
@@ -1788,7 +1788,6 @@ pg_get_sequence_data(PG_FUNCTION_ARGS)
{
#define PG_GET_SEQUENCE_DATA_COLS 2
Oid relid = PG_GETARG_OID(0);
- SeqTable elm;
Relation seqrel;
Datum values[PG_GET_SEQUENCE_DATA_COLS] = {0};
bool isnull[PG_GET_SEQUENCE_DATA_COLS] = {0};
@@ -1803,13 +1802,15 @@ pg_get_sequence_data(PG_FUNCTION_ARGS)
BOOLOID, -1, 0);
resultTupleDesc = BlessTupleDesc(resultTupleDesc);
- init_sequence(relid, &elm, &seqrel);
+ seqrel = try_relation_open(relid, AccessShareLock);
/*
- * Return all NULLs for sequences for which we lack privileges, other
- * sessions' temporary sequences, and unlogged sequences on standbys.
+ * Return all NULLs for missing sequences, sequences for which we lack
+ * privileges, other sessions' temporary sequences, and unlogged sequences
+ * on standbys.
*/
- if (pg_class_aclcheck(relid, GetUserId(), ACL_SELECT) == ACLCHECK_OK &&
+ if (seqrel && seqrel->rd_rel->relkind == RELKIND_SEQUENCE &&
+ pg_class_aclcheck(relid, GetUserId(), ACL_SELECT) == ACLCHECK_OK &&
!RELATION_IS_OTHER_TEMP(seqrel) &&
(RelationIsPermanent(seqrel) || !RecoveryInProgress()))
{
@@ -1827,7 +1828,8 @@ pg_get_sequence_data(PG_FUNCTION_ARGS)
else
memset(isnull, true, sizeof(isnull));
- sequence_close(seqrel, NoLock);
+ if (seqrel)
+ relation_close(seqrel, AccessShareLock);
resultHeapTuple = heap_form_tuple(resultTupleDesc, values, isnull);
result = HeapTupleGetDatum(resultHeapTuple);
diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
index 9decf5a524c..b00ba35f87c 100644
--- a/src/bin/pg_dump/pg_dump.c
+++ b/src/bin/pg_dump/pg_dump.c
@@ -135,6 +135,7 @@ typedef struct
int64 cache; /* cache size */
int64 last_value; /* last value of sequence */
bool is_called; /* whether nextval advances before returning */
+ bool null_seqtuple; /* did pg_get_sequence_data return nulls? */
} SequenceItem;
typedef enum OidOptions
@@ -18785,6 +18786,7 @@ collectSequences(Archive *fout)
sequences[i].cycled = (strcmp(PQgetvalue(res, i, 7), "t") == 0);
sequences[i].last_value = strtoi64(PQgetvalue(res, i, 8), NULL, 10);
sequences[i].is_called = (strcmp(PQgetvalue(res, i, 9), "t") == 0);
+ sequences[i].null_seqtuple = (PQgetisnull(res, i, 8) || PQgetisnull(res, i, 9));
}
PQclear(res);
@@ -19056,6 +19058,10 @@ dumpSequenceData(Archive *fout, const TableDataInfo *tdinfo)
bool called;
PQExpBuffer query = createPQExpBuffer();
+ /* needn't bother if not dumping sequence data */
+ if (!fout->dopt->dumpData && !fout->dopt->sequence_data)
+ return;
+
/*
* For versions >= 18, the sequence information is gathered in the sorted
* array before any calls to dumpSequenceData(). See collectSequences()
@@ -19097,6 +19103,12 @@ dumpSequenceData(Archive *fout, const TableDataInfo *tdinfo)
entry = bsearch(&key, sequences, nsequences,
sizeof(SequenceItem), SequenceItemCmp);
+ if (entry->null_seqtuple)
+ pg_fatal("failed to get data for sequence \"%s\"; user may lack "
+ "SELECT privilege on the sequence or the sequence may "
+ "have been concurrently dropped",
+ tbinfo->dobj.name);
+
last = entry->last_value;
called = entry->is_called;
}
[parent: c35e5dd9ae97]