1212 * by scanning the old xlog if necessary.
1313 * 3. Modify pg_control to reflect a "shutdown" state with a checkpoint
1414 * record at the start of xlog.
15- * 4. Flush the existing xlog files and write a new segment 0 with
16- * just a checkpoint record in it.
15+ * 4. Flush the existing xlog files and write a new segment with
16+ * just a checkpoint record in it. The new segment is positioned
17+ * just past the end of the old xlog, so that existing LSNs in
18+ * data pages will appear to be "in the past".
1719 * This is all pretty straightforward except for the intuition part of
1820 * step 2 ...
1921 *
2022 *
2123 * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
2224 * Portions Copyright (c) 1994, Regents of the University of California
2325 *
24- * $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.1 2001/03/14 00:57:43 tgl Exp $
26+ * $Header: /cvsroot/pgsql/contrib/pg_resetxlog/Attic/pg_resetxlog.c,v 1.2 2001/03/16 05:08:39 tgl Exp $
2527 *
2628 *-------------------------------------------------------------------------
2729 */
@@ -108,6 +110,7 @@ static char XLogDir[MAXPGPATH];
108110static char ControlFilePath [MAXPGPATH ];
109111
110112static ControlFileData ControlFile ;/* pg_control values */
113+ static uint32 newXlogId ,newXlogSeg ;/* ID/Segment of new XLOG segment */
111114static bool guessed = false;/* T if we had to guess at any values */
112115
113116
@@ -390,6 +393,8 @@ CheckControlVersion0(char *buffer, int len)
390393ControlFile .catalog_version_no = oldfile -> catalog_version_no ;
391394
392395ControlFile .state = oldfile -> state ;
396+ ControlFile .logId = oldfile -> logId ;
397+ ControlFile .logSeg = oldfile -> logSeg ;
393398
394399ControlFile .blcksz = oldfile -> blcksz ;
395400ControlFile .relseg_size = oldfile -> relseg_size ;
@@ -671,6 +676,8 @@ PrintControlValues(void)
671676printf ("Guessed-at pg_control values:\n\n"
672677"pg_control version number: %u\n"
673678"Catalog version number: %u\n"
679+ "Current log file id: %u\n"
680+ "Next log file segment: %u\n"
674681"Latest checkpoint's StartUpID: %u\n"
675682"Latest checkpoint's NextXID: %u\n"
676683"Latest checkpoint's NextOID: %u\n"
@@ -681,6 +688,8 @@ PrintControlValues(void)
681688
682689ControlFile .pg_control_version ,
683690ControlFile .catalog_version_no ,
691+ ControlFile .logId ,
692+ ControlFile .logSeg ,
684693ControlFile .checkPointCopy .ThisStartUpID ,
685694ControlFile .checkPointCopy .nextXid ,
686695ControlFile .checkPointCopy .nextOid ,
@@ -701,17 +710,24 @@ RewriteControlFile(void)
701710char buffer [BLCKSZ ];/* need not be aligned */
702711
703712/*
704- * Adjust fields as needed to force an empty XLOG.
713+ * Adjust fields as needed to force an empty XLOG starting at the
714+ * next available segment.
705715 */
706- ControlFile .checkPointCopy .redo .xlogid = 0 ;
707- ControlFile .checkPointCopy .redo .xrecoff = SizeOfXLogPHD ;
716+ newXlogId = ControlFile .logId ;
717+ newXlogSeg = ControlFile .logSeg ;
718+ /* be sure we wrap around correctly at end of a logfile */
719+ NextLogSeg (newXlogId ,newXlogSeg );
720+
721+ ControlFile .checkPointCopy .redo .xlogid = newXlogId ;
722+ ControlFile .checkPointCopy .redo .xrecoff =
723+ newXlogSeg * XLogSegSize + SizeOfXLogPHD ;
708724ControlFile .checkPointCopy .undo = ControlFile .checkPointCopy .redo ;
709725ControlFile .checkPointCopy .time = time (NULL );
710726
711727ControlFile .state = DB_SHUTDOWNED ;
712728ControlFile .time = time (NULL );
713- ControlFile .logId = 0 ;
714- ControlFile .logSeg = 1 ;
729+ ControlFile .logId = newXlogId ;
730+ ControlFile .logSeg = newXlogSeg + 1 ;
715731ControlFile .checkPoint = ControlFile .checkPointCopy .redo ;
716732ControlFile .prevCheckPoint .xlogid = 0 ;
717733ControlFile .prevCheckPoint .xrecoff = 0 ;
@@ -848,7 +864,7 @@ WriteEmptyXLOG(void)
848864record -> xl_crc = crc ;
849865
850866/* Write the first page */
851- XLogFileName (path ,0 , 0 );
867+ XLogFileName (path ,newXlogId , newXlogSeg );
852868
853869unlink (path );
854870