diff options
| -rw-r--r-- | src/backend/access/heap/heapam.c | 9 | ||||
| -rw-r--r-- | src/backend/access/index/indexam.c | 8 | ||||
| -rw-r--r-- | src/backend/utils/time/snapmgr.c | 19 | ||||
| -rw-r--r-- | src/include/utils/snapmgr.h | 3 |
4 files changed, 35 insertions, 4 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 0dcd6ee817e..ee692c03c3c 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1143,6 +1143,15 @@ heap_beginscan(Relation relation, Snapshot snapshot, if (!(snapshot && IsMVCCSnapshot(snapshot))) scan->rs_base.rs_flags &= ~SO_ALLOW_PAGEMODE; + /* Check that a historic snapshot is not used for non-catalog tables */ + if (snapshot && + IsHistoricMVCCSnapshot(snapshot) && + !RelationIsAccessibleInLogicalDecoding(relation)) + { + elog(ERROR, "cannot query non-catalog table \"%s\" during logical decoding", + RelationGetRelationName(relation)); + } + /* * For seqscan and sample scans in a serializable transaction, acquire a * predicate lock on the entire relation. This is required not only to diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c index 1a4f36fe0a9..31b22d9f397 100644 --- a/src/backend/access/index/indexam.c +++ b/src/backend/access/index/indexam.c @@ -263,6 +263,14 @@ index_beginscan(Relation heapRelation, Assert(snapshot != InvalidSnapshot); + /* Check that a historic snapshot is not used for non-catalog tables */ + if (IsHistoricMVCCSnapshot(snapshot) && + !RelationIsAccessibleInLogicalDecoding(heapRelation)) + { + elog(ERROR, "cannot query non-catalog table \"%s\" during logical decoding", + RelationGetRelationName(heapRelation)); + } + scan = index_beginscan_internal(indexRelation, nkeys, norderbys, snapshot, NULL, false); /* diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c index ea35f30f494..65561cc6bc3 100644 --- a/src/backend/utils/time/snapmgr.c +++ b/src/backend/utils/time/snapmgr.c @@ -271,12 +271,23 @@ Snapshot GetTransactionSnapshot(void) { /* - * This should not be called while doing logical decoding. Historic - * snapshots are only usable for catalog access, not for general-purpose - * queries. + * Return historic snapshot if doing logical decoding. + * + * Historic snapshots are only usable for catalog access, not for + * general-purpose queries. The caller is responsible for ensuring that + * the snapshot is used correctly! (PostgreSQL code never calls this + * during logical decoding, but extensions can do it.) */ if (HistoricSnapshotActive()) - elog(ERROR, "cannot take query snapshot during logical decoding"); + { + /* + * We'll never need a non-historic transaction snapshot in this + * (sub-)transaction, so there's no need to be careful to set one up + * for later calls to GetTransactionSnapshot(). + */ + Assert(!FirstSnapshotSet); + return HistoricSnapshot; + } /* First call in transaction? */ if (!FirstSnapshotSet) diff --git a/src/include/utils/snapmgr.h b/src/include/utils/snapmgr.h index d346be71642..604c1f90216 100644 --- a/src/include/utils/snapmgr.h +++ b/src/include/utils/snapmgr.h @@ -56,6 +56,9 @@ extern PGDLLIMPORT SnapshotData SnapshotToastData; ((snapshot)->snapshot_type == SNAPSHOT_MVCC || \ (snapshot)->snapshot_type == SNAPSHOT_HISTORIC_MVCC) +#define IsHistoricMVCCSnapshot(snapshot) \ + ((snapshot)->snapshot_type == SNAPSHOT_HISTORIC_MVCC) + extern Snapshot GetTransactionSnapshot(void); extern Snapshot GetLatestSnapshot(void); extern void SnapshotSetCommandId(CommandId curcid); |