mirror of
https://git.postgresql.org/git/postgresql.git
synced 2025-03-07 19:47:50 +08:00
Repair two problems with WAL logging of sequence nextvalI() ops, as
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
parent
44d7f153ae
commit
94a41d1326
@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.115 2001/11/01 06:17:01 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.115.2.1 2002/03/15 19:20:43 tgl Exp $
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*
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* NOTES
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* Transaction aborts can now occur two ways:
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@ -546,32 +546,48 @@ RecordTransactionCommit(void)
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xid = GetCurrentTransactionId();
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/*
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* We needn't write anything in xlog or clog if the transaction was
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* read-only, which we check by testing if it made any xlog entries.
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* We only need to log the commit in xlog and clog if the transaction made
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* any transaction-controlled XLOG entries. (Otherwise, its XID appears
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* nowhere in permanent storage, so no one will ever care if it
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* committed.) However, we must flush XLOG to disk if we made any XLOG
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* entries, whether in or out of transaction control. For example, if we
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* reported a nextval() result to the client, this ensures that any XLOG
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* record generated by nextval will hit the disk before we report the
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* transaction committed.
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*/
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if (MyLastRecPtr.xrecoff != 0)
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if (MyXactMadeXLogEntry)
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{
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XLogRecData rdata;
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xl_xact_commit xlrec;
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XLogRecPtr recptr;
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BufmgrCommit();
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xlrec.xtime = time(NULL);
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rdata.buffer = InvalidBuffer;
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rdata.data = (char *) (&xlrec);
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rdata.len = SizeOfXactCommit;
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rdata.next = NULL;
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START_CRIT_SECTION();
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/*
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* SHOULD SAVE ARRAY OF RELFILENODE-s TO DROP
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*/
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recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT, &rdata);
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if (MyLastRecPtr.xrecoff != 0)
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{
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/* Need to emit a commit record */
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XLogRecData rdata;
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xl_xact_commit xlrec;
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xlrec.xtime = time(NULL);
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rdata.buffer = InvalidBuffer;
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rdata.data = (char *) (&xlrec);
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rdata.len = SizeOfXactCommit;
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rdata.next = NULL;
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/*
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* XXX SHOULD SAVE ARRAY OF RELFILENODE-s TO DROP
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*/
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recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_COMMIT, &rdata);
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}
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else
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{
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/* Just flush through last record written by me */
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recptr = ProcLastRecEnd;
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}
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/*
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* Sleep before commit! So we can flush more than one commit
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* Sleep before flush! So we can flush more than one commit
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* records per single fsync. (The idea is some other backend may
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* do the XLogFlush while we're sleeping. This needs work still,
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* because on most Unixen, the minimum select() delay is 10msec or
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@ -593,15 +609,17 @@ RecordTransactionCommit(void)
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XLogFlush(recptr);
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/* Break the chain of back-links in the XLOG records I output */
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MyLastRecPtr.xrecoff = 0;
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/* Mark the transaction committed in clog */
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TransactionIdCommit(xid);
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/* Mark the transaction committed in clog, if needed */
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if (MyLastRecPtr.xrecoff != 0)
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TransactionIdCommit(xid);
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END_CRIT_SECTION();
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}
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/* Break the chain of back-links in the XLOG records I output */
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MyLastRecPtr.xrecoff = 0;
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MyXactMadeXLogEntry = false;
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/* Show myself as out of the transaction in PROC array */
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MyProc->logRec.xrecoff = 0;
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@ -689,8 +707,11 @@ RecordTransactionAbort(void)
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TransactionId xid = GetCurrentTransactionId();
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/*
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* We needn't write anything in xlog or clog if the transaction was
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* read-only, which we check by testing if it made any xlog entries.
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* We only need to log the abort in xlog and clog if the transaction made
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* any transaction-controlled XLOG entries. (Otherwise, its XID appears
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* nowhere in permanent storage, so no one will ever care if it
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* committed.) We do not flush XLOG to disk in any case, since the
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* default assumption after a crash would be that we aborted, anyway.
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*
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* Extra check here is to catch case that we aborted partway through
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* RecordTransactionCommit ...
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@ -714,11 +735,6 @@ RecordTransactionAbort(void)
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*/
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recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, &rdata);
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/*
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* There's no need for XLogFlush here, since the default
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* assumption would be that we aborted, anyway.
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*/
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/* Mark the transaction aborted in clog */
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TransactionIdAbort(xid);
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@ -727,6 +743,8 @@ RecordTransactionAbort(void)
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/* Break the chain of back-links in the XLOG records I output */
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MyLastRecPtr.xrecoff = 0;
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MyXactMadeXLogEntry = false;
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/* Show myself as out of the transaction in PROC array */
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MyProc->logRec.xrecoff = 0;
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@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.86 2002/01/14 17:55:57 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.86.2.1 2002/03/15 19:20:43 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -131,27 +131,36 @@ bool InRecovery = false;
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/*
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* MyLastRecPtr points to the start of the last XLOG record inserted by the
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* current transaction. If MyLastRecPtr.xrecoff == 0, then we are not in
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* a transaction or the transaction has not yet made any loggable changes.
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* current transaction. If MyLastRecPtr.xrecoff == 0, then the current
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* xact hasn't yet inserted any transaction-controlled XLOG records.
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*
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* Note that XLOG records inserted outside transaction control are not
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* reflected into MyLastRecPtr.
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* reflected into MyLastRecPtr. They do, however, cause MyXactMadeXLogEntry
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* to be set true. The latter can be used to test whether the current xact
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* made any loggable changes (including out-of-xact changes, such as
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* sequence updates).
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*/
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XLogRecPtr MyLastRecPtr = {0, 0};
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bool MyXactMadeXLogEntry = false;
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/*
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* ProcLastRecPtr points to the start of the last XLOG record inserted by the
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* current backend. It is updated for all inserts, transaction-controlled
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* or not.
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* or not. ProcLastRecEnd is similar but points to end+1 of last record.
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*/
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static XLogRecPtr ProcLastRecPtr = {0, 0};
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XLogRecPtr ProcLastRecEnd = {0, 0};
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/*
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* RedoRecPtr is this backend's local copy of the REDO record pointer
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* (which is almost but not quite the same as a pointer to the most recent
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* CHECKPOINT record). We update this from the shared-memory copy,
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* XLogCtl->Insert.RedoRecPtr, whenever we can safely do so (ie, when we
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* hold the Insert lock). See XLogInsert for details.
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* hold the Insert lock). See XLogInsert for details. We are also allowed
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* to update from XLogCtl->Insert.RedoRecPtr if we hold the info_lck;
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* see GetRedoRecPtr.
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*/
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static XLogRecPtr RedoRecPtr;
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@ -272,7 +281,8 @@ typedef struct XLogCtlData
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StartUpID ThisStartUpID;
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/* This value is not protected by *any* lock... */
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XLogRecPtr RedoRecPtr; /* see SetRedoRecPtr/GetRedoRecPtr */
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/* see SetSavedRedoRecPtr/GetSavedRedoRecPtr */
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XLogRecPtr SavedRedoRecPtr;
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slock_t info_lck; /* locks shared LogwrtRqst/LogwrtResult */
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} XLogCtlData;
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@ -777,6 +787,7 @@ begin:;
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MyLastRecPtr = RecPtr;
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ProcLastRecPtr = RecPtr;
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Insert->PrevRecord = RecPtr;
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MyXactMadeXLogEntry = true;
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Insert->currpos += SizeOfXLogRecord;
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freespace -= SizeOfXLogRecord;
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@ -855,6 +866,8 @@ begin:;
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SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
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}
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ProcLastRecEnd = RecPtr;
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END_CRIT_SECTION();
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return (RecPtr);
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@ -2538,7 +2551,7 @@ StartupXLOG(void)
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ThisStartUpID = checkPoint.ThisStartUpID;
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RedoRecPtr = XLogCtl->Insert.RedoRecPtr =
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XLogCtl->RedoRecPtr = checkPoint.redo;
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XLogCtl->SavedRedoRecPtr = checkPoint.redo;
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if (XLByteLT(RecPtr, checkPoint.redo))
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elog(STOP, "invalid redo in checkpoint record");
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@ -2824,32 +2837,47 @@ void
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SetThisStartUpID(void)
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{
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ThisStartUpID = XLogCtl->ThisStartUpID;
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RedoRecPtr = XLogCtl->RedoRecPtr;
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RedoRecPtr = XLogCtl->SavedRedoRecPtr;
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}
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/*
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* CheckPoint process called by postmaster saves copy of new RedoRecPtr
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* in shmem (using SetRedoRecPtr). When checkpointer completes, postmaster
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* calls GetRedoRecPtr to update its own copy of RedoRecPtr, so that
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* subsequently-spawned backends will start out with a reasonably up-to-date
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* local RedoRecPtr. Since these operations are not protected by any lock
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* and copying an XLogRecPtr isn't atomic, it's unsafe to use either of these
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* routines at other times!
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*
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* Note: once spawned, a backend must update its local RedoRecPtr from
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* XLogCtl->Insert.RedoRecPtr while holding the insert lock. This is
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* done in XLogInsert().
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* in shmem (using SetSavedRedoRecPtr). When checkpointer completes,
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* postmaster calls GetSavedRedoRecPtr to update its own copy of RedoRecPtr,
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* so that subsequently-spawned backends will start out with a reasonably
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* up-to-date local RedoRecPtr. Since these operations are not protected by
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* any lock and copying an XLogRecPtr isn't atomic, it's unsafe to use either
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* of these routines at other times!
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*/
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void
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SetRedoRecPtr(void)
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SetSavedRedoRecPtr(void)
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{
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XLogCtl->RedoRecPtr = RedoRecPtr;
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XLogCtl->SavedRedoRecPtr = RedoRecPtr;
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}
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void
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GetSavedRedoRecPtr(void)
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{
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RedoRecPtr = XLogCtl->SavedRedoRecPtr;
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}
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/*
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* Once spawned, a backend may update its local RedoRecPtr from
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* XLogCtl->Insert.RedoRecPtr; it must hold the insert lock or info_lck
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* to do so. This is done in XLogInsert() or GetRedoRecPtr().
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*/
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XLogRecPtr
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GetRedoRecPtr(void)
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{
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RedoRecPtr = XLogCtl->RedoRecPtr;
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/* use volatile pointer to prevent code rearrangement */
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volatile XLogCtlData *xlogctl = XLogCtl;
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SpinLockAcquire_NoHoldoff(&xlogctl->info_lck);
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Assert(XLByteLE(RedoRecPtr, xlogctl->Insert.RedoRecPtr));
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RedoRecPtr = xlogctl->Insert.RedoRecPtr;
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SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
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return RedoRecPtr;
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}
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/*
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@ -2862,6 +2890,7 @@ ShutdownXLOG(void)
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/* suppress in-transaction check in CreateCheckPoint */
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MyLastRecPtr.xrecoff = 0;
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MyXactMadeXLogEntry = false;
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CritSectionCount++;
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CreateDummyCaches();
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@ -2886,7 +2915,7 @@ CreateCheckPoint(bool shutdown)
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uint32 _logId;
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uint32 _logSeg;
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if (MyLastRecPtr.xrecoff != 0)
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if (MyXactMadeXLogEntry)
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elog(ERROR, "CreateCheckPoint: cannot be called inside transaction block");
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/*
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@ -2972,9 +3001,16 @@ CreateCheckPoint(bool shutdown)
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/*
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* Here we update the shared RedoRecPtr for future XLogInsert calls;
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* this must be done while holding the insert lock.
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* this must be done while holding the insert lock AND the info_lck.
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*/
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RedoRecPtr = XLogCtl->Insert.RedoRecPtr = checkPoint.redo;
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{
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/* use volatile pointer to prevent code rearrangement */
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volatile XLogCtlData *xlogctl = XLogCtl;
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SpinLockAcquire_NoHoldoff(&xlogctl->info_lck);
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RedoRecPtr = xlogctl->Insert.RedoRecPtr = checkPoint.redo;
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SpinLockRelease_NoHoldoff(&xlogctl->info_lck);
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}
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/*
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* Get UNDO record ptr - this is oldest of PROC->logRec values. We do
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@ -8,7 +8,7 @@
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.120 2002/01/10 01:11:45 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.120.2.1 2002/03/15 19:20:44 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -380,7 +380,7 @@ BootstrapMain(int argc, char *argv[])
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InitDummyProcess(); /* needed to get LWLocks */
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CreateDummyCaches();
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CreateCheckPoint(false);
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SetRedoRecPtr();
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SetSavedRedoRecPtr(); /* pass redo ptr back to postmaster */
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proc_exit(0); /* done */
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case BS_XLOG_STARTUP:
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/commands/sequence.c,v 1.68 2002/01/11 18:16:04 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/commands/sequence.c,v 1.68.2.1 2002/03/15 19:20:45 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -286,6 +286,7 @@ nextval(PG_FUNCTION_ARGS)
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char *seqname = get_seq_name(seqin);
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SeqTable elm;
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Buffer buf;
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Page page;
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Form_pg_sequence seq;
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int64 incby,
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maxv,
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@ -316,6 +317,7 @@ nextval(PG_FUNCTION_ARGS)
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seq = read_info("nextval", elm, &buf); /* lock page' buffer and
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* read tuple */
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page = BufferGetPage(buf);
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last = next = result = seq->last_value;
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incby = seq->increment_by;
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@ -331,11 +333,33 @@ nextval(PG_FUNCTION_ARGS)
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log--;
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}
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/*
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* Decide whether we should emit a WAL log record. If so, force up
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* the fetch count to grab SEQ_LOG_VALS more values than we actually
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* need to cache. (These will then be usable without logging.)
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*
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* If this is the first nextval after a checkpoint, we must force
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* a new WAL record to be written anyway, else replay starting from the
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* checkpoint would fail to advance the sequence past the logged
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* values. In this case we may as well fetch extra values.
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*/
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if (log < fetch)
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{
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fetch = log = fetch - log + SEQ_LOG_VALS;
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/* forced log to satisfy local demand for values */
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fetch = log = fetch + SEQ_LOG_VALS;
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logit = true;
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}
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else
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{
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XLogRecPtr redoptr = GetRedoRecPtr();
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if (XLByteLE(PageGetLSN(page), redoptr))
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{
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/* last update of seq was before checkpoint */
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fetch = log = fetch + SEQ_LOG_VALS;
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logit = true;
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}
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}
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while (fetch) /* try to fetch cache [+ log ] numbers */
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{
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@ -386,6 +410,9 @@ nextval(PG_FUNCTION_ARGS)
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}
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}
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log -= fetch; /* adjust for any unfetched numbers */
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Assert(log >= 0);
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/* save info in local cache */
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elm->last = result; /* last returned number */
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elm->cached = last; /* last fetched number */
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@ -396,7 +423,6 @@ nextval(PG_FUNCTION_ARGS)
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xl_seq_rec xlrec;
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XLogRecPtr recptr;
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XLogRecData rdata[2];
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Page page = BufferGetPage(buf);
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xlrec.node = elm->rel->rd_node;
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rdata[0].buffer = InvalidBuffer;
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@ -417,15 +443,11 @@ nextval(PG_FUNCTION_ARGS)
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PageSetLSN(page, recptr);
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PageSetSUI(page, ThisStartUpID);
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if (fetch) /* not all numbers were fetched */
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log -= fetch;
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}
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/* update on-disk data */
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seq->last_value = last; /* last fetched number */
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seq->is_called = true;
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Assert(log >= 0);
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seq->log_cnt = log; /* how much is logged */
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END_CRIT_SECTION();
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@ -37,7 +37,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.264 2002/01/10 01:11:45 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.264.2.1 2002/03/15 19:20:47 tgl Exp $
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*
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* NOTES
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*
|
||||
@ -1692,7 +1692,7 @@ CleanupProc(int pid,
|
||||
{
|
||||
checkpointed = time(NULL);
|
||||
/* Update RedoRecPtr for future child backends */
|
||||
GetRedoRecPtr();
|
||||
GetSavedRedoRecPtr();
|
||||
}
|
||||
}
|
||||
else
|
||||
|
||||
@ -6,7 +6,7 @@
|
||||
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
|
||||
* Portions Copyright (c) 1994, Regents of the University of California
|
||||
*
|
||||
* $Id: xlog.h,v 1.28 2001/11/05 17:46:31 momjian Exp $
|
||||
* $Id: xlog.h,v 1.28.2.1 2002/03/15 19:20:47 tgl Exp $
|
||||
*/
|
||||
#ifndef XLOG_H
|
||||
#define XLOG_H
|
||||
@ -178,6 +178,8 @@ typedef struct XLogRecData
|
||||
extern StartUpID ThisStartUpID; /* current SUI */
|
||||
extern bool InRecovery;
|
||||
extern XLogRecPtr MyLastRecPtr;
|
||||
extern bool MyXactMadeXLogEntry;
|
||||
extern XLogRecPtr ProcLastRecEnd;
|
||||
|
||||
/* these variables are GUC parameters related to XLOG */
|
||||
extern int CheckPointSegments;
|
||||
@ -205,8 +207,9 @@ extern void ShutdownXLOG(void);
|
||||
extern void CreateCheckPoint(bool shutdown);
|
||||
extern void SetThisStartUpID(void);
|
||||
extern void XLogPutNextOid(Oid nextOid);
|
||||
extern void SetRedoRecPtr(void);
|
||||
extern void GetRedoRecPtr(void);
|
||||
extern void SetSavedRedoRecPtr(void);
|
||||
extern void GetSavedRedoRecPtr(void);
|
||||
extern XLogRecPtr GetRedoRecPtr(void);
|
||||
|
||||
/* in storage/ipc/sinval.c, but don't want to declare in sinval.h because
|
||||
* we'd have to include xlog.h into that ...
|
||||
|
||||
Loading…
Reference in New Issue
Block a user