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@ -7,7 +7,7 @@ |
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* Portions Copyright (c) 1996-2007, 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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* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.273 2007/06/28 00:02:37 tgl Exp $ |
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* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.274 2007/06/30 19:12:01 tgl Exp $ |
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* |
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*------------------------------------------------------------------------- |
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*/ |
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@ -66,6 +66,7 @@ char *XLogArchiveCommand = NULL; |
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char *XLOG_sync_method = NULL; |
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const char XLOG_sync_method_default[] = DEFAULT_SYNC_METHOD_STR; |
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bool fullPageWrites = true; |
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bool log_checkpoints = false; |
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#ifdef WAL_DEBUG |
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bool XLOG_DEBUG = false; |
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@ -92,6 +93,13 @@ static int open_sync_bit = DEFAULT_SYNC_FLAGBIT; |
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#define XLOG_SYNC_BIT (enableFsync ? open_sync_bit : 0) |
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/*
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* Statistics for current checkpoint are collected in this global struct. |
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* Because only the background writer or a stand-alone backend can perform |
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* checkpoints, this will be unused in normal backends. |
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*/ |
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CheckpointStatsData CheckpointStats; |
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/*
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* ThisTimeLineID will be same in all backends --- it identifies current |
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* WAL timeline for the database system. |
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@ -414,9 +422,8 @@ static int XLogFileRead(uint32 log, uint32 seg, int emode); |
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static void XLogFileClose(void); |
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static bool RestoreArchivedFile(char *path, const char *xlogfname, |
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const char *recovername, off_t expectedSize); |
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static int PreallocXlogFiles(XLogRecPtr endptr); |
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static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr, |
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int *nsegsremoved, int *nsegsrecycled); |
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static void PreallocXlogFiles(XLogRecPtr endptr); |
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static void RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr); |
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static void CleanupBackupHistory(void); |
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static XLogRecord *ReadRecord(XLogRecPtr *RecPtr, int emode); |
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static bool ValidXLOGHeader(XLogPageHeader hdr, int emode); |
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@ -1578,10 +1585,10 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch) |
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Write->lastSegSwitchTime = time(NULL); |
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/*
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* Signal bgwriter to start a checkpoint if it's been too long |
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* since the last one. (We look at local copy of RedoRecPtr |
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* which might be a little out of date, but should be close |
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* enough for this purpose.) |
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* Signal bgwriter to start a checkpoint if we've consumed too |
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* much xlog since the last one. (We look at local copy of |
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* RedoRecPtr which might be a little out of date, but should |
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* be close enough for this purpose.) |
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* |
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* A straight computation of segment number could overflow 32 |
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* bits. Rather than assuming we have working 64-bit |
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@ -1603,13 +1610,7 @@ XLogWrite(XLogwrtRqst WriteRqst, bool flexible, bool xlog_switch) |
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new_highbits = openLogId / XLogSegSize; |
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if (new_highbits != old_highbits || |
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new_segno >= old_segno + (uint32) (CheckPointSegments-1)) |
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{ |
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#ifdef WAL_DEBUG |
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if (XLOG_DEBUG) |
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elog(LOG, "time for a checkpoint, signaling bgwriter"); |
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#endif |
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RequestCheckpoint(CHECKPOINT_WARNONTIME); |
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} |
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RequestCheckpoint(CHECKPOINT_CAUSE_XLOG); |
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} |
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} |
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} |
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@ -1855,7 +1856,7 @@ XLogFileInit(uint32 log, uint32 seg, |
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{ |
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char path[MAXPGPATH]; |
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char tmppath[MAXPGPATH]; |
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char zbuffer[XLOG_BLCKSZ]; |
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char *zbuffer; |
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uint32 installed_log; |
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uint32 installed_seg; |
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int max_advance; |
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@ -1889,6 +1890,8 @@ XLogFileInit(uint32 log, uint32 seg, |
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* pre-creating an extra log segment. That seems OK, and better than |
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* holding the lock throughout this lengthy process. |
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*/ |
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elog(DEBUG2, "creating and filling new WAL file"); |
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snprintf(tmppath, MAXPGPATH, XLOGDIR "/xlogtemp.%d", (int) getpid()); |
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unlink(tmppath); |
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@ -1909,12 +1912,16 @@ XLogFileInit(uint32 log, uint32 seg, |
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* fsync below) that all the indirect blocks are down on disk. Therefore, |
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* fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the |
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* log file. |
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* |
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* Note: palloc zbuffer, instead of just using a local char array, to |
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* ensure it is reasonably well-aligned; this may save a few cycles |
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* transferring data to the kernel. |
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*/ |
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MemSet(zbuffer, 0, sizeof(zbuffer)); |
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for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(zbuffer)) |
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zbuffer = (char *) palloc0(XLOG_BLCKSZ); |
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for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ) |
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{ |
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errno = 0; |
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if ((int) write(fd, zbuffer, sizeof(zbuffer)) != (int) sizeof(zbuffer)) |
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if ((int) write(fd, zbuffer, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ) |
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{ |
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int save_errno = errno; |
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@ -1930,6 +1937,7 @@ XLogFileInit(uint32 log, uint32 seg, |
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errmsg("could not write to file \"%s\": %m", tmppath))); |
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} |
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} |
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pfree(zbuffer); |
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if (pg_fsync(fd) != 0) |
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ereport(ERROR, |
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@ -1960,6 +1968,8 @@ XLogFileInit(uint32 log, uint32 seg, |
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unlink(tmppath); |
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} |
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elog(DEBUG2, "done creating and filling new WAL file"); |
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/* Set flag to tell caller there was no existent file */ |
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*use_existent = false; |
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@ -2525,10 +2535,9 @@ RestoreArchivedFile(char *path, const char *xlogfname, |
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* recycled log segments, but the startup transient is likely to include |
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* a lot of segment creations by foreground processes, which is not so good. |
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*/ |
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static int |
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static void |
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PreallocXlogFiles(XLogRecPtr endptr) |
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{ |
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int nsegsadded = 0; |
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uint32 _logId; |
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uint32 _logSeg; |
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int lf; |
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@ -2543,9 +2552,8 @@ PreallocXlogFiles(XLogRecPtr endptr) |
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lf = XLogFileInit(_logId, _logSeg, &use_existent, true); |
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close(lf); |
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if (!use_existent) |
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nsegsadded++; |
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CheckpointStats.ckpt_segs_added++; |
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} |
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return nsegsadded; |
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} |
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/*
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@ -2555,8 +2563,7 @@ PreallocXlogFiles(XLogRecPtr endptr) |
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* whether we want to recycle rather than delete no-longer-wanted log files. |
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*/ |
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static void |
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RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr, |
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int *nsegsremoved, int *nsegsrecycled) |
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RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr) |
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{ |
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uint32 endlogId; |
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uint32 endlogSeg; |
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@ -2566,9 +2573,6 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr, |
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char lastoff[MAXFNAMELEN]; |
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char path[MAXPGPATH]; |
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*nsegsremoved = 0; |
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*nsegsrecycled = 0; |
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/*
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* Initialize info about where to try to recycle to. We allow recycling |
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* segments up to XLOGfileslop segments beyond the current XLOG location. |
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@ -2617,7 +2621,7 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr, |
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ereport(DEBUG2, |
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(errmsg("recycled transaction log file \"%s\"", |
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xlde->d_name))); |
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(*nsegsrecycled)++; |
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CheckpointStats.ckpt_segs_recycled++; |
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/* Needn't recheck that slot on future iterations */ |
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if (max_advance > 0) |
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{ |
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@ -2632,7 +2636,7 @@ RemoveOldXlogFiles(uint32 log, uint32 seg, XLogRecPtr endptr, |
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(errmsg("removing transaction log file \"%s\"", |
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xlde->d_name))); |
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unlink(path); |
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(*nsegsremoved)++; |
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CheckpointStats.ckpt_segs_removed++; |
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} |
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XLogArchiveCleanup(xlde->d_name); |
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@ -5127,7 +5131,7 @@ StartupXLOG(void) |
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/*
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* Preallocate additional log files, if wanted. |
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*/ |
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(void) PreallocXlogFiles(EndOfLog); |
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PreallocXlogFiles(EndOfLog); |
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/*
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* Okay, we're officially UP. |
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@ -5421,6 +5425,57 @@ ShutdownXLOG(int code, Datum arg) |
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(errmsg("database system is shut down"))); |
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} |
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/*
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* Log start of a checkpoint. |
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*/ |
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static void |
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LogCheckpointStart(int flags) |
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{ |
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elog(LOG, "checkpoint starting:%s%s%s%s%s%s", |
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(flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "", |
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(flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "", |
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(flags & CHECKPOINT_FORCE) ? " force" : "", |
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(flags & CHECKPOINT_WAIT) ? " wait" : "", |
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(flags & CHECKPOINT_CAUSE_XLOG) ? " xlog" : "", |
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(flags & CHECKPOINT_CAUSE_TIME) ? " time" : ""); |
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} |
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/*
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* Log end of a checkpoint. |
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*/ |
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static void |
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LogCheckpointEnd(void) |
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{ |
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long write_secs, sync_secs, total_secs; |
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int write_usecs, sync_usecs, total_usecs; |
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CheckpointStats.ckpt_end_t = GetCurrentTimestamp(); |
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TimestampDifference(CheckpointStats.ckpt_start_t, |
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CheckpointStats.ckpt_end_t, |
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&total_secs, &total_usecs); |
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TimestampDifference(CheckpointStats.ckpt_write_t, |
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CheckpointStats.ckpt_sync_t, |
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&write_secs, &write_usecs); |
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TimestampDifference(CheckpointStats.ckpt_sync_t, |
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CheckpointStats.ckpt_sync_end_t, |
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&sync_secs, &sync_usecs); |
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elog(LOG, "checkpoint complete: wrote %d buffers (%.1f%%); " |
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"%d transaction log file(s) added, %d removed, %d recycled; " |
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"write=%ld.%03d s, sync=%ld.%03d s, total=%ld.%03d s", |
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CheckpointStats.ckpt_bufs_written, |
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(double) CheckpointStats.ckpt_bufs_written * 100 / NBuffers, |
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CheckpointStats.ckpt_segs_added, |
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CheckpointStats.ckpt_segs_removed, |
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CheckpointStats.ckpt_segs_recycled, |
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write_secs, write_usecs/1000, |
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sync_secs, sync_usecs/1000, |
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total_secs, total_usecs/1000); |
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} |
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/*
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* Perform a checkpoint --- either during shutdown, or on-the-fly |
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* |
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@ -5431,7 +5486,7 @@ ShutdownXLOG(int code, Datum arg) |
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* CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occured |
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* since the last one (implied by CHECKPOINT_IS_SHUTDOWN). |
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* |
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* Note: flags might contain other bits of interest to RequestCheckpoint. |
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* Note: flags contains other bits, of interest here only for logging purposes. |
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* In particular note that this routine is synchronous and does not pay |
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* attention to CHECKPOINT_WAIT. |
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*/ |
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@ -5446,9 +5501,6 @@ CreateCheckPoint(int flags) |
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uint32 freespace; |
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uint32 _logId; |
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uint32 _logSeg; |
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int nsegsadded = 0; |
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int nsegsremoved = 0; |
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int nsegsrecycled = 0; |
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TransactionId *inCommitXids; |
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int nInCommit; |
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@ -5460,6 +5512,16 @@ CreateCheckPoint(int flags) |
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*/ |
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LWLockAcquire(CheckpointLock, LW_EXCLUSIVE); |
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/*
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* Prepare to accumulate statistics. |
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* |
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* Note: because it is possible for log_checkpoints to change while a |
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* checkpoint proceeds, we always accumulate stats, even if |
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* log_checkpoints is currently off. |
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*/ |
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MemSet(&CheckpointStats, 0, sizeof(CheckpointStats)); |
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CheckpointStats.ckpt_start_t = GetCurrentTimestamp(); |
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/*
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* Use a critical section to force system panic if we have trouble. |
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*/ |
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@ -5560,9 +5622,12 @@ CreateCheckPoint(int flags) |
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*/ |
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LWLockRelease(WALInsertLock); |
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if (!shutdown) |
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ereport(DEBUG2, |
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(errmsg("checkpoint starting"))); |
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/*
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* If enabled, log checkpoint start. We postpone this until now |
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* so as not to log anything if we decided to skip the checkpoint. |
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*/ |
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if (log_checkpoints) |
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LogCheckpointStart(flags); |
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/*
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* Before flushing data, we must wait for any transactions that are |
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@ -5699,8 +5764,7 @@ CreateCheckPoint(int flags) |
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if (_logId || _logSeg) |
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{ |
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PrevLogSeg(_logId, _logSeg); |
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RemoveOldXlogFiles(_logId, _logSeg, recptr, |
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&nsegsremoved, &nsegsrecycled); |
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RemoveOldXlogFiles(_logId, _logSeg, recptr); |
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} |
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/*
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@ -5708,7 +5772,7 @@ CreateCheckPoint(int flags) |
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* segments, since that may supply some of the needed files.) |
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*/ |
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if (!shutdown) |
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nsegsadded = PreallocXlogFiles(recptr); |
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PreallocXlogFiles(recptr); |
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/*
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* Truncate pg_subtrans if possible. We can throw away all data before |
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@ -5720,10 +5784,9 @@ CreateCheckPoint(int flags) |
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if (!InRecovery) |
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TruncateSUBTRANS(GetOldestXmin(true, false)); |
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if (!shutdown) |
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ereport(DEBUG2, |
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(errmsg("checkpoint complete; %d transaction log file(s) added, %d removed, %d recycled", |
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nsegsadded, nsegsremoved, nsegsrecycled))); |
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/* All real work is done, but log before releasing lock. */ |
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if (log_checkpoints) |
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LogCheckpointEnd(); |
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LWLockRelease(CheckpointLock); |
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} |
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Tom Lane
18 years ago