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Repair two problems with WAL logging of sequence nextvalI() ops, as

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per recent pghackers discussion: force a new WAL record at first nextval
after a checkpoint, and ensure that xlog is flushed to disk if a nextval
record is the only thing emitted by a transaction.
This commit is contained in:
Tom Lane
2002-03-15 19:20:36 +00:00
parent 0b73fe14f1
commit 01747692fe
6 changed files with 147 additions and 68 deletions
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76
src/backend/access/transam/xact.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.117 2002/03/06 06:09:21 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.118 2002/03/15 19:20:29 tgl Exp $
*
* NOTES
* Transaction aborts can now occur two ways:
@ -546,32 +546,48 @@ RecordTransactionCommit(void)
xid = GetCurrentTransactionId();
/*
* We needn't write anything in xlog or clog if the transaction was
* read-only, which we check by testing if it made any xlog entries.
* We only need to log the commit in xlog and clog if the transaction made
* any transaction-controlled XLOG entries. (Otherwise, its XID appears
* nowhere in permanent storage, so no one will ever care if it
* committed.) However, we must flush XLOG to disk if we made any XLOG
* entries, whether in or out of transaction control. For example, if we
* reported a nextval() result to the client, this ensures that any XLOG
* record generated by nextval will hit the disk before we report the
* transaction committed.
*/
if (MyLastRecPtr.xrecoff != 0)
if (MyXactMadeXLogEntry)
{
XLogRecData rdata;
xl_xact_commit xlrec;
XLogRecPtr recptr;
BufmgrCommit();
xlrec.xtime = time(NULL);
rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&xlrec);
rdata.len = SizeOfXactCommit;
rdata.next = NULL;
START_CRIT_SECTION();
/*
* SHOULD SAVE ARRAY OF RELFILENODE-s TO DROP
*/
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT, &rdata);
if (MyLastRecPtr.xrecoff != 0)
{
/* Need to emit a commit record */
XLogRecData rdata;
xl_xact_commit xlrec;
xlrec.xtime = time(NULL);
rdata.buffer = InvalidBuffer;
rdata.data = (char *) (&xlrec);
rdata.len = SizeOfXactCommit;
rdata.next = NULL;
/*
* XXX SHOULD SAVE ARRAY OF RELFILENODE-s TO DROP
*/
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT, &rdata);
}
else
{
/* Just flush through last record written by me */
recptr = ProcLastRecEnd;
}
/*
* Sleep before commit! So we can flush more than one commit
* Sleep before flush! So we can flush more than one commit
* records per single fsync. (The idea is some other backend may
* do the XLogFlush while we're sleeping. This needs work still,
* because on most Unixen, the minimum select() delay is 10msec or
@ -593,15 +609,17 @@ RecordTransactionCommit(void)
XLogFlush(recptr);
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
/* Mark the transaction committed in clog */
TransactionIdCommit(xid);
/* Mark the transaction committed in clog, if needed */
if (MyLastRecPtr.xrecoff != 0)
TransactionIdCommit(xid);
END_CRIT_SECTION();
}
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
/* Show myself as out of the transaction in PROC array */
MyProc->logRec.xrecoff = 0;
@ -689,8 +707,11 @@ RecordTransactionAbort(void)
TransactionId xid = GetCurrentTransactionId();
/*
* We needn't write anything in xlog or clog if the transaction was
* read-only, which we check by testing if it made any xlog entries.
* We only need to log the abort in xlog and clog if the transaction made
* any transaction-controlled XLOG entries. (Otherwise, its XID appears
* nowhere in permanent storage, so no one will ever care if it
* committed.) We do not flush XLOG to disk in any case, since the
* default assumption after a crash would be that we aborted, anyway.
*
* Extra check here is to catch case that we aborted partway through
* RecordTransactionCommit ...
@ -714,11 +735,6 @@ RecordTransactionAbort(void)
*/
recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, &rdata);
/*
* There's no need for XLogFlush here, since the default
* assumption would be that we aborted, anyway.
*/
/* Mark the transaction aborted in clog */
TransactionIdAbort(xid);
@ -727,6 +743,8 @@ RecordTransactionAbort(void)
/* Break the chain of back-links in the XLOG records I output */
MyLastRecPtr.xrecoff = 0;
MyXactMadeXLogEntry = false;
/* Show myself as out of the transaction in PROC array */
MyProc->logRec.xrecoff = 0;