diff --git a/doc/src/sgml/runtime.sgml b/doc/src/sgml/runtime.sgml
index f321cea669b486797ccfa48238558423d3bce0f6..f7b9f26f4347b6971cd70f026578e2fb0c7722dd 100644
--- a/doc/src/sgml/runtime.sgml
+++ b/doc/src/sgml/runtime.sgml
@@ -1,5 +1,5 @@
<!--
-$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.56 2001/03/13 01:17:05 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/runtime.sgml,v 1.57 2001/03/16 05:44:33 tgl Exp $
-->
<Chapter Id="runtime">
@@ -1224,8 +1224,8 @@ env PGOPTIONS='-c geqo=off' psql
<term>WAL_BUFFERS (<type>integer</type>)</term>
<listitem>
<para>
- Number of disk-page buffers for WAL log. This option can only be set
- at server start.
+ Number of disk-page buffers in shared memory for WAL log.
+ This option can only be set at server start.
</para>
</listitem>
</varlistentry>
@@ -1250,6 +1250,23 @@ env PGOPTIONS='-c geqo=off' psql
</para>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term>WAL_SYNC_METHOD (<type>string</type>)</term>
+ <listitem>
+ <para>
+ Method used for forcing WAL updates out to disk. Possible
+ values are
+ <literal>FSYNC</> (call fsync() at each commit),
+ <literal>FDATASYNC</> (call fdatasync() at each commit),
+ <literal>OPEN_SYNC</> (write WAL files with open() option O_SYNC), or
+ <literal>OPEN_DATASYNC</> (write WAL files with open() option O_DSYNC).
+ Not all of these choices are available on all platforms.
+ This option can only be set at server start or in the
+ <filename>postgresql.conf</filename> file.
+ </para>
+ </listitem>
+ </varlistentry>
</variablelist>
</para>
</sect2>
diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml
index c92ccd9d23029355090f533409c0886480c603a0..69616409e8140617d8cd88a033480930d0e311a4 100644
--- a/doc/src/sgml/wal.sgml
+++ b/doc/src/sgml/wal.sgml
@@ -1,4 +1,4 @@
-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.4 2001/03/13 01:17:05 tgl Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/wal.sgml,v 1.5 2001/03/16 05:44:33 tgl Exp $ -->
<chapter id="wal">
<title>Write-Ahead Logging (<acronym>WAL</acronym>)</title>
@@ -281,15 +281,6 @@
<command>CHECKPOINT</command>.
</para>
- <para>
- Setting the <varname>WAL_DEBUG</varname> parameter to any non-zero
- value will result in each <function>LogInsert</function> and
- <function>LogFlush</function> <acronym>WAL</acronym> call being
- logged to standard error. At present, it makes no difference what
- the non-zero value is. This option may be replaced by a more
- general mechanism in the future.
- </para>
-
<para>
The <varname>COMMIT_DELAY</varname> parameter defines for how many
microseconds the backend will sleep after writing a commit
@@ -304,6 +295,24 @@
ten milliseconds, so that any nonzero <varname>COMMIT_DELAY</varname>
setting between 1 and 10000 microseconds will have the same effect.
</para>
+
+ <para>
+ The <varname>WAL_SYNC_METHOD</varname> parameter determines how
+ Postgres will ask the kernel to force WAL updates out to disk.
+ All the options should be the same as far as reliability goes,
+ but it's quite platform-specific which one will be the fastest.
+ Note that this parameter is irrelevant if <varname>FSYNC</varname>
+ has been turned off.
+ </para>
+
+ <para>
+ Setting the <varname>WAL_DEBUG</varname> parameter to any non-zero
+ value will result in each <function>LogInsert</function> and
+ <function>LogFlush</function> <acronym>WAL</acronym> call being
+ logged to standard error. At present, it makes no difference what
+ the non-zero value is. This option may be replaced by a more
+ general mechanism in the future.
+ </para>
</sect1>
</chapter>
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 6c2ce3f1bd791d14301fdfcbd9638adfafbdea48..d2d75d652c911fb553c04f783029078a6d29e0ee 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.58 2001/03/14 20:23:04 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.59 2001/03/16 05:44:33 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -42,6 +42,47 @@
#include "miscadmin.h"
+/*
+ * This chunk of hackery attempts to determine which file sync methods
+ * are available on the current platform, and to choose an appropriate
+ * default method. We assume that fsync() is always available, and that
+ * configure determined whether fdatasync() is.
+ */
+#define SYNC_METHOD_FSYNC 0
+#define SYNC_METHOD_FDATASYNC 1
+#define SYNC_METHOD_OPEN 2 /* used for both O_SYNC and O_DSYNC */
+
+#if defined(O_SYNC)
+# define OPEN_SYNC_FLAG O_SYNC
+#else
+# if defined(O_FSYNC)
+# define OPEN_SYNC_FLAG O_FSYNC
+# endif
+#endif
+
+#if defined(OPEN_SYNC_FLAG)
+# if defined(O_DSYNC) && (O_DSYNC != OPEN_SYNC_FLAG)
+# define OPEN_DATASYNC_FLAG O_DSYNC
+# endif
+#endif
+
+#if defined(OPEN_DATASYNC_FLAG)
+# define DEFAULT_SYNC_METHOD_STR "open_datasync"
+# define DEFAULT_SYNC_METHOD SYNC_METHOD_OPEN
+# define DEFAULT_SYNC_FLAGBIT OPEN_DATASYNC_FLAG
+#else
+# if defined(HAVE_FDATASYNC)
+# define DEFAULT_SYNC_METHOD_STR "fdatasync"
+# define DEFAULT_SYNC_METHOD SYNC_METHOD_FDATASYNC
+# define DEFAULT_SYNC_FLAGBIT 0
+# else
+# define DEFAULT_SYNC_METHOD_STR "fsync"
+# define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC
+# define DEFAULT_SYNC_FLAGBIT 0
+# endif
+#endif
+
+
/* Max time to wait to acquire XLog activity locks */
#define XLOG_LOCK_TIMEOUT (5*60*1000000) /* 5 minutes */
/* Max time to wait to acquire checkpoint lock */
@@ -52,10 +93,18 @@ int CheckPointSegments = 3;
int XLOGbuffers = 8;
int XLOGfiles = 0; /* how many files to pre-allocate during ckpt */
int XLOG_DEBUG = 0;
+char *XLOG_sync_method = NULL;
+const char XLOG_sync_method_default[] = DEFAULT_SYNC_METHOD_STR;
char XLOG_archive_dir[MAXPGPATH]; /* null string means delete 'em */
+/* these are derived from XLOG_sync_method by assign_xlog_sync_method */
+static int sync_method = DEFAULT_SYNC_METHOD;
+static int open_sync_bit = DEFAULT_SYNC_FLAGBIT;
+
#define MinXLOGbuffers 4
+#define XLOG_SYNC_BIT (enableFsync ? open_sync_bit : 0)
+
/*
* ThisStartUpID will be same in all backends --- it identifies current
@@ -365,6 +414,7 @@ static void WriteControlFile(void);
static void ReadControlFile(void);
static char *str_time(time_t tnow);
static void xlog_outrec(char *buf, XLogRecord *record);
+static void issue_xlog_fsync(void);
/*
@@ -917,6 +967,15 @@ XLogWrite(XLogwrtRqst WriteRqst)
while (XLByteLT(LogwrtResult.Write, WriteRqst.Write))
{
+ /*
+ * Make sure we're not ahead of the insert process. This could
+ * happen if we're passed a bogus WriteRqst.Write that is past the
+ * end of the last page that's been initialized by
+ * AdvanceXLInsertBuffer.
+ */
+ if (!XLByteLT(LogwrtResult.Write, XLogCtl->xlblocks[Write->curridx]))
+ elog(STOP, "XLogWrite: write request is past end of log");
+
/* Advance LogwrtResult.Write to end of current buffer page */
LogwrtResult.Write = XLogCtl->xlblocks[Write->curridx];
ispartialpage = XLByteLT(WriteRqst.Write, LogwrtResult.Write);
@@ -1004,9 +1063,7 @@ XLogWrite(XLogwrtRqst WriteRqst)
*/
if (openLogOff >= XLogSegSize && !ispartialpage)
{
- if (pg_fdatasync(openLogFile) != 0)
- elog(STOP, "fsync(logfile %u seg %u) failed: %m",
- openLogId, openLogSeg);
+ issue_xlog_fsync();
LogwrtResult.Flush = LogwrtResult.Write; /* end of current page */
}
@@ -1030,24 +1087,24 @@ XLogWrite(XLogwrtRqst WriteRqst)
* we might have no open file or the wrong one. However, we do
* not need to fsync more than one file.
*/
- if (openLogFile >= 0 &&
- !XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
+ if (sync_method != SYNC_METHOD_OPEN)
{
- if (close(openLogFile) != 0)
- elog(STOP, "close(logfile %u seg %u) failed: %m",
- openLogId, openLogSeg);
- openLogFile = -1;
- }
- if (openLogFile < 0)
- {
- XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg);
- openLogFile = XLogFileOpen(openLogId, openLogSeg, false);
- openLogOff = 0;
+ if (openLogFile >= 0 &&
+ !XLByteInPrevSeg(LogwrtResult.Write, openLogId, openLogSeg))
+ {
+ if (close(openLogFile) != 0)
+ elog(STOP, "close(logfile %u seg %u) failed: %m",
+ openLogId, openLogSeg);
+ openLogFile = -1;
+ }
+ if (openLogFile < 0)
+ {
+ XLByteToPrevSeg(LogwrtResult.Write, openLogId, openLogSeg);
+ openLogFile = XLogFileOpen(openLogId, openLogSeg, false);
+ openLogOff = 0;
+ }
+ issue_xlog_fsync();
}
-
- if (pg_fdatasync(openLogFile) != 0)
- elog(STOP, "fsync(logfile %u seg %u) failed: %m",
- openLogId, openLogSeg);
LogwrtResult.Flush = LogwrtResult.Write;
}
@@ -1191,7 +1248,8 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
*/
if (*usexistent)
{
- fd = BasicOpenFile(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
+ fd = BasicOpenFile(path, O_RDWR | PG_BINARY | XLOG_SYNC_BIT,
+ S_IRUSR | S_IWUSR);
if (fd < 0)
{
if (errno != ENOENT)
@@ -1208,6 +1266,7 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
unlink(tpath);
unlink(path);
+ /* do not use XLOG_SYNC_BIT here --- want to fsync only at end of fill */
fd = BasicOpenFile(tpath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
S_IRUSR | S_IWUSR);
if (fd < 0)
@@ -1220,8 +1279,8 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
* allow "holes" in files, just seeking to the end doesn't allocate
* intermediate space. This way, we know that we have all the space
* and (after the fsync below) that all the indirect blocks are down
- * on disk. Therefore, fdatasync(2) will be sufficient to sync future
- * writes to the log file.
+ * on disk. Therefore, fdatasync(2) or O_DSYNC will be sufficient to
+ * sync future writes to the log file.
*/
MemSet(zbuffer, 0, sizeof(zbuffer));
for (nbytes = 0; nbytes < XLogSegSize; nbytes += sizeof(zbuffer))
@@ -1261,7 +1320,8 @@ XLogFileInit(uint32 log, uint32 seg, bool *usexistent)
log, seg);
#endif
- fd = BasicOpenFile(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
+ fd = BasicOpenFile(path, O_RDWR | PG_BINARY | XLOG_SYNC_BIT,
+ S_IRUSR | S_IWUSR);
if (fd < 0)
elog(STOP, "InitReopen(logfile %u seg %u) failed: %m",
log, seg);
@@ -1280,7 +1340,8 @@ XLogFileOpen(uint32 log, uint32 seg, bool econt)
XLogFileName(path, log, seg);
- fd = BasicOpenFile(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
+ fd = BasicOpenFile(path, O_RDWR | PG_BINARY | XLOG_SYNC_BIT,
+ S_IRUSR | S_IWUSR);
if (fd < 0)
{
if (econt && errno == ENOENT)
@@ -1845,7 +1906,8 @@ WriteControlFile(void)
memset(buffer, 0, BLCKSZ);
memcpy(buffer, ControlFile, sizeof(ControlFileData));
- fd = BasicOpenFile(ControlFilePath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY, S_IRUSR | S_IWUSR);
+ fd = BasicOpenFile(ControlFilePath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
+ S_IRUSR | S_IWUSR);
if (fd < 0)
elog(STOP, "WriteControlFile failed to create control file (%s): %m",
ControlFilePath);
@@ -2852,3 +2914,120 @@ xlog_outrec(char *buf, XLogRecord *record)
sprintf(buf + strlen(buf), ": %s",
RmgrTable[record->xl_rmid].rm_name);
}
+
+
+/*
+ * GUC support routines
+ */
+
+bool
+check_xlog_sync_method(const char *method)
+{
+ if (strcasecmp(method, "fsync") == 0) return true;
+#ifdef HAVE_FDATASYNC
+ if (strcasecmp(method, "fdatasync") == 0) return true;
+#endif
+#ifdef OPEN_SYNC_FLAG
+ if (strcasecmp(method, "open_sync") == 0) return true;
+#endif
+#ifdef OPEN_DATASYNC_FLAG
+ if (strcasecmp(method, "open_datasync") == 0) return true;
+#endif
+ return false;
+}
+
+void
+assign_xlog_sync_method(const char *method)
+{
+ int new_sync_method;
+ int new_sync_bit;
+
+ if (strcasecmp(method, "fsync") == 0)
+ {
+ new_sync_method = SYNC_METHOD_FSYNC;
+ new_sync_bit = 0;
+ }
+#ifdef HAVE_FDATASYNC
+ else if (strcasecmp(method, "fdatasync") == 0)
+ {
+ new_sync_method = SYNC_METHOD_FDATASYNC;
+ new_sync_bit = 0;
+ }
+#endif
+#ifdef OPEN_SYNC_FLAG
+ else if (strcasecmp(method, "open_sync") == 0)
+ {
+ new_sync_method = SYNC_METHOD_OPEN;
+ new_sync_bit = OPEN_SYNC_FLAG;
+ }
+#endif
+#ifdef OPEN_DATASYNC_FLAG
+ else if (strcasecmp(method, "open_datasync") == 0)
+ {
+ new_sync_method = SYNC_METHOD_OPEN;
+ new_sync_bit = OPEN_DATASYNC_FLAG;
+ }
+#endif
+ else
+ {
+ /* Can't get here unless guc.c screwed up */
+ elog(ERROR, "Bogus xlog sync method %s", method);
+ new_sync_method = 0; /* keep compiler quiet */
+ new_sync_bit = 0;
+ }
+
+ if (sync_method != new_sync_method || open_sync_bit != new_sync_bit)
+ {
+ /*
+ * To ensure that no blocks escape unsynced, force an fsync on
+ * the currently open log segment (if any). Also, if the open
+ * flag is changing, close the log file so it will be reopened
+ * (with new flag bit) at next use.
+ */
+ if (openLogFile >= 0)
+ {
+ if (pg_fsync(openLogFile) != 0)
+ elog(STOP, "fsync(logfile %u seg %u) failed: %m",
+ openLogId, openLogSeg);
+ if (open_sync_bit != new_sync_bit)
+ {
+ if (close(openLogFile) != 0)
+ elog(STOP, "close(logfile %u seg %u) failed: %m",
+ openLogId, openLogSeg);
+ openLogFile = -1;
+ }
+ }
+ sync_method = new_sync_method;
+ open_sync_bit = new_sync_bit;
+ }
+}
+
+
+/*
+ * Issue appropriate kind of fsync (if any) on the current XLOG output file
+ */
+static void
+issue_xlog_fsync(void)
+{
+ switch (sync_method)
+ {
+ case SYNC_METHOD_FSYNC:
+ if (pg_fsync(openLogFile) != 0)
+ elog(STOP, "fsync(logfile %u seg %u) failed: %m",
+ openLogId, openLogSeg);
+ break;
+#ifdef HAVE_FDATASYNC
+ case SYNC_METHOD_FDATASYNC:
+ if (pg_fdatasync(openLogFile) != 0)
+ elog(STOP, "fdatasync(logfile %u seg %u) failed: %m",
+ openLogId, openLogSeg);
+ break;
+#endif
+ case SYNC_METHOD_OPEN:
+ /* write synced it already */
+ break;
+ default:
+ elog(STOP, "bogus sync_method %d", sync_method);
+ break;
+ }
+}
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 7e6769d3c8949de840886449fc299f41dff6b865..d05bb75a2944b6b6d9d547a061290eb0cd59afd5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4,7 +4,7 @@
* Support for grand unified configuration scheme, including SET
* command, configuration file, and command line options.
*
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.32 2001/03/13 01:17:06 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.33 2001/03/16 05:44:33 tgl Exp $
*
* Copyright 2000 by PostgreSQL Global Development Group
* Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -20,6 +20,7 @@
#include "utils/guc.h"
+#include "access/xlog.h"
#include "commands/async.h"
#include "libpq/auth.h"
#include "libpq/pqcomm.h"
@@ -33,23 +34,17 @@
#include "tcop/tcopprot.h"
-/* XXX should be in a header file */
+/* XXX these should be in other modules' header files */
extern bool Log_connections;
-
-extern int CheckPointSegments;
extern int CheckPointTimeout;
-extern int XLOGbuffers;
-extern int XLOGfiles;
-extern int XLOG_DEBUG;
extern int CommitDelay;
extern int CommitSiblings;
-
extern bool FixBTree;
#ifdef ENABLE_SYSLOG
extern char *Syslog_facility;
extern char *Syslog_ident;
-bool check_facility(const char *facility);
+static bool check_facility(const char *facility);
#endif
/*
@@ -138,7 +133,8 @@ struct config_string
GucContext context;
char **variable;
const char *default_val;
- bool (*parse_hook)(const char *);
+ bool (*parse_hook)(const char *proposed);
+ void (*assign_hook)(const char *newval);
};
@@ -330,25 +326,29 @@ static struct config_string
ConfigureNamesString[] =
{
{"krb_server_keyfile", PGC_POSTMASTER, &pg_krb_server_keyfile,
- PG_KRB_SRVTAB, NULL},
-
- {"unix_socket_group", PGC_POSTMASTER, &Unix_socket_group,
- "", NULL},
+ PG_KRB_SRVTAB, NULL, NULL},
#ifdef ENABLE_SYSLOG
{"syslog_facility", PGC_POSTMASTER, &Syslog_facility,
- "LOCAL0", check_facility},
+ "LOCAL0", check_facility, NULL},
{"syslog_ident", PGC_POSTMASTER, &Syslog_ident,
- "postgres", NULL},
+ "postgres", NULL, NULL},
#endif
+ {"unix_socket_group", PGC_POSTMASTER, &Unix_socket_group,
+ "", NULL, NULL},
+
{"unix_socket_directory", PGC_POSTMASTER, &UnixSocketDir,
- "", NULL},
+ "", NULL, NULL},
{"virtual_host", PGC_POSTMASTER, &VirtualHost,
- "", NULL},
+ "", NULL, NULL},
- {NULL, 0, NULL, NULL, NULL}
+ {"wal_sync_method", PGC_SIGHUP, &XLOG_sync_method,
+ XLOG_sync_method_default,
+ check_xlog_sync_method, assign_xlog_sync_method},
+
+ {NULL, 0, NULL, NULL, NULL, NULL}
};
/******** end of options list ********/
@@ -723,7 +723,10 @@ set_config_option(const char * name, const char * value, GucContext
elog(elevel, "out of memory");
return false;
}
- free(*conf->variable);
+ if (conf->assign_hook)
+ (conf->assign_hook)(str);
+ if (*conf->variable)
+ free(*conf->variable);
*conf->variable = str;
}
}
@@ -737,7 +740,10 @@ set_config_option(const char * name, const char * value, GucContext
elog(elevel, "out of memory");
return false;
}
- free(*conf->variable);
+ if (conf->assign_hook)
+ (conf->assign_hook)(str);
+ if (*conf->variable)
+ free(*conf->variable);
*conf->variable = str;
}
break;
@@ -855,7 +861,7 @@ ParseLongOption(const char * string, char ** name, char ** value)
#ifdef ENABLE_SYSLOG
-bool
+static bool
check_facility(const char *facility)
{
if (strcasecmp(facility,"LOCAL0") == 0) return true;
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 88d1fe94370dd6621cbfd413fb8975801e6c6435..d6641f516662bb03b5f2e5b0d48e99d153a79919 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -107,6 +107,8 @@
#
#wal_buffers = 8 # min 4
#wal_files = 0 # range 0-64
+#wal_sync_method = fsync # fsync or fdatasync or open_sync or open_datasync
+# Note: default wal_sync_method varies across platforms
#wal_debug = 0 # range 0-16
#commit_delay = 0 # range 0-100000
#commit_siblings = 5 # range 1-1000
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index fa51d68d39ecd861814b9a4073652e1822f940f4..d2dfb2e31c6cd25763a5efdf2dac272883961df8 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -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 1.20 2001/03/13 20:32:37 tgl Exp $
+ * $Id: xlog.h,v 1.21 2001/03/16 05:44:33 tgl Exp $
*/
#ifndef XLOG_H
#define XLOG_H
@@ -176,6 +176,15 @@ extern StartUpID ThisStartUpID; /* current SUI */
extern bool InRecovery;
extern XLogRecPtr MyLastRecPtr;
+/* these variables are GUC parameters related to XLOG */
+extern int CheckPointSegments;
+extern int XLOGbuffers;
+extern int XLOGfiles;
+extern int XLOG_DEBUG;
+extern char *XLOG_sync_method;
+extern const char XLOG_sync_method_default[];
+
+
extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
extern void XLogFlush(XLogRecPtr RecPtr);
@@ -202,4 +211,7 @@ extern void GetRedoRecPtr(void);
*/
extern XLogRecPtr GetUndoRecPtr(void);
+extern bool check_xlog_sync_method(const char *method);
+extern void assign_xlog_sync_method(const char *method);
+
#endif /* XLOG_H */