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-rw-r--r--src/backend/access/heap/heapam.c76
1 files changed, 43 insertions, 33 deletions
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 9790ba22982..d18c5ca6f58 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -6792,7 +6792,7 @@ heap_freeze_execute_prepared(Relation rel, Buffer buffer,
Page page = BufferGetPage(buffer);
Assert(ntuples > 0);
- Assert(TransactionIdIsValid(FreezeLimit));
+ Assert(TransactionIdIsNormal(FreezeLimit));
START_CRIT_SECTION();
@@ -6815,21 +6815,20 @@ heap_freeze_execute_prepared(Relation rel, Buffer buffer,
int nplans;
xl_heap_freeze_page xlrec;
XLogRecPtr recptr;
- TransactionId latestRemovedXid;
+ TransactionId snapshotConflictHorizon;
/* Prepare deduplicated representation for use in WAL record */
nplans = heap_xlog_freeze_plan(tuples, ntuples, plans, offsets);
/*
- * latestRemovedXid describes the latest processed XID, whereas
* FreezeLimit is (approximately) the first XID not frozen by VACUUM.
* Back up caller's FreezeLimit to avoid false conflicts when
* FreezeLimit is precisely equal to VACUUM's OldestXmin cutoff.
*/
- latestRemovedXid = FreezeLimit;
- TransactionIdRetreat(latestRemovedXid);
+ snapshotConflictHorizon = FreezeLimit;
+ TransactionIdRetreat(snapshotConflictHorizon);
- xlrec.latestRemovedXid = latestRemovedXid;
+ xlrec.snapshotConflictHorizon = snapshotConflictHorizon;
xlrec.nplans = nplans;
XLogBeginInsert();
@@ -7401,15 +7400,21 @@ heap_tuple_would_freeze(HeapTupleHeader tuple, TransactionId cutoff_xid,
}
/*
- * If 'tuple' contains any visible XID greater than latestRemovedXid,
- * ratchet forwards latestRemovedXid to the greatest one found.
- * This is used as the basis for generating Hot Standby conflicts, so
- * if a tuple was never visible then removing it should not conflict
- * with queries.
+ * Maintain snapshotConflictHorizon for caller by ratcheting forward its value
+ * using any committed XIDs contained in 'tuple', an obsolescent heap tuple
+ * that caller is in the process of physically removing, e.g. via HOT pruning
+ * or index deletion.
+ *
+ * Caller must initialize its value to InvalidTransactionId, which is
+ * generally interpreted as "definitely no need for a recovery conflict".
+ * Final value must reflect all heap tuples that caller will physically remove
+ * (or remove TID references to) via its ongoing pruning/deletion operation.
+ * ResolveRecoveryConflictWithSnapshot() is passed the final value (taken from
+ * caller's WAL record) by REDO routine when it replays caller's operation.
*/
void
-HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple,
- TransactionId *latestRemovedXid)
+HeapTupleHeaderAdvanceConflictHorizon(HeapTupleHeader tuple,
+ TransactionId *snapshotConflictHorizon)
{
TransactionId xmin = HeapTupleHeaderGetXmin(tuple);
TransactionId xmax = HeapTupleHeaderGetUpdateXid(tuple);
@@ -7417,8 +7422,8 @@ HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple,
if (tuple->t_infomask & HEAP_MOVED)
{
- if (TransactionIdPrecedes(*latestRemovedXid, xvac))
- *latestRemovedXid = xvac;
+ if (TransactionIdPrecedes(*snapshotConflictHorizon, xvac))
+ *snapshotConflictHorizon = xvac;
}
/*
@@ -7431,11 +7436,9 @@ HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple,
(!HeapTupleHeaderXminInvalid(tuple) && TransactionIdDidCommit(xmin)))
{
if (xmax != xmin &&
- TransactionIdFollows(xmax, *latestRemovedXid))
- *latestRemovedXid = xmax;
+ TransactionIdFollows(xmax, *snapshotConflictHorizon))
+ *snapshotConflictHorizon = xmax;
}
-
- /* *latestRemovedXid may still be invalid at end */
}
#ifdef USE_PREFETCH
@@ -7558,7 +7561,7 @@ TransactionId
heap_index_delete_tuples(Relation rel, TM_IndexDeleteOp *delstate)
{
/* Initial assumption is that earlier pruning took care of conflict */
- TransactionId latestRemovedXid = InvalidTransactionId;
+ TransactionId snapshotConflictHorizon = InvalidTransactionId;
BlockNumber blkno = InvalidBlockNumber;
Buffer buf = InvalidBuffer;
Page page = NULL;
@@ -7769,8 +7772,8 @@ heap_index_delete_tuples(Relation rel, TM_IndexDeleteOp *delstate)
}
/*
- * Maintain latestRemovedXid value for deletion operation as a whole
- * by advancing current value using heap tuple headers. This is
+ * Maintain snapshotConflictHorizon value for deletion operation as a
+ * whole by advancing current value using heap tuple headers. This is
* loosely based on the logic for pruning a HOT chain.
*/
offnum = ItemPointerGetOffsetNumber(htid);
@@ -7805,12 +7808,12 @@ heap_index_delete_tuples(Relation rel, TM_IndexDeleteOp *delstate)
* LP_DEAD item. This is okay because the earlier pruning
* operation that made the line pointer LP_DEAD in the first place
* must have considered the original tuple header as part of
- * generating its own latestRemovedXid value.
+ * generating its own snapshotConflictHorizon value.
*
* Relying on XLOG_HEAP2_PRUNE records like this is the same
* strategy that index vacuuming uses in all cases. Index VACUUM
- * WAL records don't even have a latestRemovedXid field of their
- * own for this reason.
+ * WAL records don't even have a snapshotConflictHorizon field of
+ * their own for this reason.
*/
if (!ItemIdIsNormal(lp))
break;
@@ -7824,7 +7827,8 @@ heap_index_delete_tuples(Relation rel, TM_IndexDeleteOp *delstate)
!TransactionIdEquals(HeapTupleHeaderGetXmin(htup), priorXmax))
break;
- HeapTupleHeaderAdvanceLatestRemovedXid(htup, &latestRemovedXid);
+ HeapTupleHeaderAdvanceConflictHorizon(htup,
+ &snapshotConflictHorizon);
/*
* If the tuple is not HOT-updated, then we are at the end of this
@@ -7856,7 +7860,7 @@ heap_index_delete_tuples(Relation rel, TM_IndexDeleteOp *delstate)
Assert(finalndeltids > 0 || delstate->bottomup);
delstate->ndeltids = finalndeltids;
- return latestRemovedXid;
+ return snapshotConflictHorizon;
}
/*
@@ -8232,6 +8236,9 @@ bottomup_sort_and_shrink(TM_IndexDeleteOp *delstate)
* corresponding visibility map block. Both should have already been modified
* and dirtied.
*
+ * snapshotConflictHorizon comes from the largest xmin on the page being
+ * marked all-visible. REDO routine uses it to generate recovery conflicts.
+ *
* If checksums or wal_log_hints are enabled, we may also generate a full-page
* image of heap_buffer. Otherwise, we optimize away the FPI (by specifying
* REGBUF_NO_IMAGE for the heap buffer), in which case the caller should *not*
@@ -8239,7 +8246,7 @@ bottomup_sort_and_shrink(TM_IndexDeleteOp *delstate)
*/
XLogRecPtr
log_heap_visible(RelFileLocator rlocator, Buffer heap_buffer, Buffer vm_buffer,
- TransactionId cutoff_xid, uint8 vmflags)
+ TransactionId snapshotConflictHorizon, uint8 vmflags)
{
xl_heap_visible xlrec;
XLogRecPtr recptr;
@@ -8248,7 +8255,7 @@ log_heap_visible(RelFileLocator rlocator, Buffer heap_buffer, Buffer vm_buffer,
Assert(BufferIsValid(heap_buffer));
Assert(BufferIsValid(vm_buffer));
- xlrec.cutoff_xid = cutoff_xid;
+ xlrec.snapshotConflictHorizon = snapshotConflictHorizon;
xlrec.flags = vmflags;
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapVisible);
@@ -8683,7 +8690,8 @@ heap_xlog_prune(XLogReaderState *record)
* no queries running for which the removed tuples are still visible.
*/
if (InHotStandby)
- ResolveRecoveryConflictWithSnapshot(xlrec->latestRemovedXid, rlocator);
+ ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
+ rlocator);
/*
* If we have a full-page image, restore it (using a cleanup lock) and
@@ -8851,7 +8859,8 @@ heap_xlog_visible(XLogReaderState *record)
* rather than killing the transaction outright.
*/
if (InHotStandby)
- ResolveRecoveryConflictWithSnapshot(xlrec->cutoff_xid, rlocator);
+ ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
+ rlocator);
/*
* Read the heap page, if it still exists. If the heap file has dropped or
@@ -8939,7 +8948,7 @@ heap_xlog_visible(XLogReaderState *record)
visibilitymap_pin(reln, blkno, &vmbuffer);
visibilitymap_set(reln, blkno, InvalidBuffer, lsn, vmbuffer,
- xlrec->cutoff_xid, xlrec->flags);
+ xlrec->snapshotConflictHorizon, xlrec->flags);
ReleaseBuffer(vmbuffer);
FreeFakeRelcacheEntry(reln);
@@ -9105,7 +9114,8 @@ heap_xlog_freeze_page(XLogReaderState *record)
RelFileLocator rlocator;
XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
- ResolveRecoveryConflictWithSnapshot(xlrec->latestRemovedXid, rlocator);
+ ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
+ rlocator);
}
if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
generated by cgit v1.2.3 (git 2.46.0) at 2025-08-17 16:51:26 +0000