VACUUM must make sure that a HEAP_MARKED_FOR_UPDATE tuple gets marked

tglsfdc · tglsfdc · commit 5ab0ad5c7e70 · 2002-01-11T20:07:03.000Z
as either HEAP_XMAX_COMMITTED or HEAP_XMAX_INVALID once the updating
transaction is gone.  Otherwise some other transaction may come along
and try to test the commit status of t_xmax later --- which could be
after VACUUM has recycled the CLOG status for that xact.  Bug introduced
in post-beta4 bug fix.
diff --git a/src/backend/utils/time/tqual.c b/src/backend/utils/time/tqual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.45 2001/12/19 17:18:39 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.46 2002/01/11 20:07:03 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -742,7 +742,21 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
 
 	if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
 	{
-		/* "deleting" xact really only marked it for update */
+		/*
+		 * "Deleting" xact really only marked it for update, so the tuple
+		 * is live in any case.  However, we must make sure that either
+		 * XMAX_COMMITTED or XMAX_INVALID gets set once the xact is gone;
+		 * otherwise it is unsafe to recycle CLOG status after vacuuming.
+		 */
+		if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))
+		{
+			if (TransactionIdIsInProgress(tuple->t_xmax))
+				return HEAPTUPLE_LIVE;
+			if (TransactionIdDidCommit(tuple->t_xmax))
+				tuple->t_infomask |= HEAP_XMAX_COMMITTED;
+			else				/* it's either aborted or crashed */
+				tuple->t_infomask |= HEAP_XMAX_INVALID;
+		}
 		return HEAPTUPLE_LIVE;
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.45 2001/12/19 17:18:39 tgl Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.46 2002/01/11 20:07:03 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -742,7 +742,21 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)`
`742`	`742`
`743`	`743`	`if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)`
`744`	`744`	`{`
`745`		`- /* "deleting" xact really only marked it for update */`
	`745`	`+ /*`
	`746`	`+ * "Deleting" xact really only marked it for update, so the tuple`
	`747`	`+ * is live in any case. However, we must make sure that either`
	`748`	`+ * XMAX_COMMITTED or XMAX_INVALID gets set once the xact is gone;`
	`749`	`+ * otherwise it is unsafe to recycle CLOG status after vacuuming.`
	`750`	`+ */`
	`751`	`+ if (!(tuple->t_infomask & HEAP_XMAX_COMMITTED))`
	`752`	`+ {`
	`753`	`+ if (TransactionIdIsInProgress(tuple->t_xmax))`
	`754`	`+ return HEAPTUPLE_LIVE;`
	`755`	`+ if (TransactionIdDidCommit(tuple->t_xmax))`
	`756`	`+ tuple->t_infomask \|= HEAP_XMAX_COMMITTED;`
	`757`	`+ else /* it's either aborted or crashed */`
	`758`	`+ tuple->t_infomask \|= HEAP_XMAX_INVALID;`
	`759`	`+ }`
`746`	`760`	`return HEAPTUPLE_LIVE;`
`747`	`761`	`}`
`748`	`762`