diff options
| -rw-r--r-- | src/backend/access/heap/heapam.c | 52 | ||||
| -rw-r--r-- | src/backend/access/heap/pruneheap.c | 4 | ||||
| -rw-r--r-- | src/backend/executor/execMain.c | 6 | ||||
| -rw-r--r-- | src/include/access/heapam.h | 3 |
4 files changed, 54 insertions, 11 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c index 5c61a80bf22..093f226045b 100644 --- a/src/backend/access/heap/heapam.c +++ b/src/backend/access/heap/heapam.c @@ -1824,8 +1824,7 @@ heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer, * broken. */ if (TransactionIdIsValid(prev_xmax) && - !TransactionIdEquals(prev_xmax, - HeapTupleHeaderGetXmin(heapTuple->t_data))) + !HeapTupleUpdateXmaxMatchesXmin(prev_xmax, heapTuple->t_data)) break; /* @@ -2007,7 +2006,7 @@ heap_get_latest_tid(Relation relation, * tuple. Check for XMIN match. */ if (TransactionIdIsValid(priorXmax) && - !TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(tp.t_data))) + !HeapTupleUpdateXmaxMatchesXmin(priorXmax, tp.t_data)) { UnlockReleaseBuffer(buffer); break; @@ -2039,6 +2038,50 @@ heap_get_latest_tid(Relation relation, } /* end of loop */ } +/* + * HeapTupleUpdateXmaxMatchesXmin - verify update chain xmax/xmin lineage + * + * Given the new version of a tuple after some update, verify whether the + * given Xmax (corresponding to the previous version) matches the tuple's + * Xmin, taking into account that the Xmin might have been frozen after the + * update. + */ +bool +HeapTupleUpdateXmaxMatchesXmin(TransactionId xmax, HeapTupleHeader htup) +{ + TransactionId xmin = HeapTupleHeaderGetXmin(htup); + + /* + * If the xmax of the old tuple is identical to the xmin of the new one, + * it's a match. + */ + if (TransactionIdEquals(xmax, xmin)) + return true; + + /* + * If the Xmin that was in effect prior to a freeze matches the Xmax, + * it's good too. + */ + if (HeapTupleHeaderXminFrozen(htup) && + TransactionIdEquals(HeapTupleHeaderGetRawXmin(htup), xmax)) + return true; + + /* + * When a tuple is frozen, the original Xmin is lost, but we know it's a + * committed transaction. So unless the Xmax is InvalidXid, we don't know + * for certain that there is a match, but there may be one; and we must + * return true so that a HOT chain that is half-frozen can be walked + * correctly. + * + * We no longer freeze tuples this way, but we must keep this in order to + * interpret pre-pg_upgrade pages correctly. + */ + if (TransactionIdEquals(xmin, FrozenTransactionId) && + TransactionIdIsValid(xmax)) + return true; + + return false; +} /* * UpdateXmaxHintBits - update tuple hint bits after xmax transaction ends @@ -5400,8 +5443,7 @@ l4: * end of the chain, we're done, so return success. */ if (TransactionIdIsValid(priorXmax) && - !TransactionIdEquals(HeapTupleHeaderGetXmin(mytup.t_data), - priorXmax)) + !HeapTupleUpdateXmaxMatchesXmin(priorXmax, mytup.t_data)) { UnlockReleaseBuffer(buf); return HeapTupleMayBeUpdated; diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c index 563e5c353cd..822d6f8000c 100644 --- a/src/backend/access/heap/pruneheap.c +++ b/src/backend/access/heap/pruneheap.c @@ -465,7 +465,7 @@ heap_prune_chain(Relation relation, Buffer buffer, OffsetNumber rootoffnum, * Check the tuple XMIN against prior XMAX, if any */ if (TransactionIdIsValid(priorXmax) && - !TransactionIdEquals(HeapTupleHeaderGetXmin(htup), priorXmax)) + !HeapTupleUpdateXmaxMatchesXmin(priorXmax, htup)) break; /* @@ -805,7 +805,7 @@ heap_get_root_tuples(Page page, OffsetNumber *root_offsets) htup = (HeapTupleHeader) PageGetItem(page, lp); if (TransactionIdIsValid(priorXmax) && - !TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(htup))) + !HeapTupleUpdateXmaxMatchesXmin(priorXmax, htup)) break; /* Remember the root line pointer for this item */ diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c index 66331fc8b00..80c8088d9ef 100644 --- a/src/backend/executor/execMain.c +++ b/src/backend/executor/execMain.c @@ -2243,8 +2243,7 @@ EvalPlanQualFetch(EState *estate, Relation relation, int lockmode, * atomic, and Xmin never changes in an existing tuple, except to * invalid or frozen, and neither of those can match priorXmax.) */ - if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple.t_data), - priorXmax)) + if (!HeapTupleUpdateXmaxMatchesXmin(priorXmax, tuple.t_data)) { ReleaseBuffer(buffer); return NULL; @@ -2391,8 +2390,7 @@ EvalPlanQualFetch(EState *estate, Relation relation, int lockmode, /* * As above, if xmin isn't what we're expecting, do nothing. */ - if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple.t_data), - priorXmax)) + if (!HeapTupleUpdateXmaxMatchesXmin(priorXmax, tuple.t_data)) { ReleaseBuffer(buffer); return NULL; diff --git a/src/include/access/heapam.h b/src/include/access/heapam.h index 75e6b72f9e0..291cdc52fde 100644 --- a/src/include/access/heapam.h +++ b/src/include/access/heapam.h @@ -139,6 +139,9 @@ extern void heap_get_latest_tid(Relation relation, Snapshot snapshot, ItemPointer tid); extern void setLastTid(const ItemPointer tid); +extern bool HeapTupleUpdateXmaxMatchesXmin(TransactionId xmax, + HeapTupleHeader htup); + extern BulkInsertState GetBulkInsertState(void); extern void FreeBulkInsertState(BulkInsertState); |