Hello,
attached is a simple patch which makes it possible to change the system
identifier of the cluster in pg_control. This is useful for
individualization of the instance that is started on top of data
directory produced by pg_basebackup - something that's helpful for
logical replication setup where you need to easily identify each node
(it's used by Bidirectional Replication for example).
--
Petr Jelinek http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
diff --git a/doc/src/sgml/ref/pg_resetxlog.sgml b/doc/src/sgml/ref/pg_resetxlog.sgml
index 34b0606..39ae574 100644
--- a/doc/src/sgml/ref/pg_resetxlog.sgml
+++ b/doc/src/sgml/ref/pg_resetxlog.sgml
@@ -30,6 +30,7 @@ PostgreSQL documentation
<arg choice="opt"><option>-m</option> <replaceable class="parameter">mxid</replaceable>,<replaceable class="parameter">mxid</replaceable></arg>
<arg choice="opt"><option>-O</option> <replaceable class="parameter">mxoff</replaceable></arg>
<arg choice="opt"><option>-l</option> <replaceable class="parameter">xlogfile</replaceable></arg>
+ <arg choice="opt"><option>-s</option> [<replaceable class="parameter">sysid</replaceable>]</arg>
<arg choice="plain"><replaceable>datadir</replaceable></arg>
</cmdsynopsis>
</refsynopsisdiv>
@@ -184,6 +185,13 @@ PostgreSQL documentation
</para>
<para>
+ The <option>-s</> option instructs <command>pg_resetxlog</command> to
+ set the system identifier of the cluster to specified <replaceable>sysid</>.
+ If the <replaceable>sysid</> is not provided new one will be generated using
+ same algorithm <command>initdb</> uses.
+ </para>
+
+ <para>
The <option>-V</> and <option>--version</> options print
the <application>pg_resetxlog</application> version and exit. The
options <option>-?</> and <option>--help</> show supported arguments,
diff --git a/src/bin/pg_resetxlog/pg_resetxlog.c b/src/bin/pg_resetxlog/pg_resetxlog.c
index 915a1ed..3660ee1 100644
--- a/src/bin/pg_resetxlog/pg_resetxlog.c
+++ b/src/bin/pg_resetxlog/pg_resetxlog.c
@@ -67,7 +67,9 @@ static MultiXactId set_mxid = 0;
static MultiXactOffset set_mxoff = (MultiXactOffset) -1;
static uint32 minXlogTli = 0;
static XLogSegNo minXlogSegNo = 0;
+static uint64 set_sysid = 0;
+static uint64 GenerateSystemIdentifier(void);
static bool ReadControlFile(void);
static void GuessControlValues(void);
static void PrintControlValues(bool guessed);
@@ -111,7 +113,7 @@ main(int argc, char *argv[])
}
- while ((c = getopt(argc, argv, "fl:m:no:O:x:e:")) != -1)
+ while ((c = getopt(argc, argv, "fl:m:no:O:x:e:s::")) != -1)
{
switch (c)
{
@@ -227,6 +229,22 @@ main(int argc, char *argv[])
XLogFromFileName(optarg, &minXlogTli, &minXlogSegNo);
break;
+ case 's':
+ if (optarg)
+ {
+ if (sscanf(optarg, UINT64_FORMAT, &set_sysid) != 1)
+ {
+ fprintf(stderr, _("%s: invalid argument for option -s\n"), progname);
+ fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
+ exit(1);
+ }
+ }
+ else
+ {
+ set_sysid = GenerateSystemIdentifier();
+ }
+ break;
+
default:
fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
exit(1);
@@ -354,6 +372,9 @@ main(int argc, char *argv[])
if (minXlogSegNo > newXlogSegNo)
newXlogSegNo = minXlogSegNo;
+ if (set_sysid != 0)
+ ControlFile.system_identifier = set_sysid;
+
/*
* If we had to guess anything, and -f was not given, just print the
* guessed values and exit. Also print if -n is given.
@@ -395,6 +416,26 @@ main(int argc, char *argv[])
/*
+ * Create a new unique installation identifier.
+ *
+ * See notes in xlog.c about the algorithm.
+ */
+static uint64
+GenerateSystemIdentifier(void)
+{
+ uint64 sysidentifier;
+ struct timeval tv;
+
+ gettimeofday(&tv, NULL);
+ sysidentifier = ((uint64) tv.tv_sec) << 32;
+ sysidentifier |= ((uint64) tv.tv_usec) << 12;
+ sysidentifier |= getpid() & 0xFFF;
+
+ return sysidentifier;
+}
+
+
+/*
* Try to read the existing pg_control file.
*
* This routine is also responsible for updating old pg_control versions
@@ -475,9 +516,6 @@ ReadControlFile(void)
static void
GuessControlValues(void)
{
- uint64 sysidentifier;
- struct timeval tv;
-
/*
* Set up a completely default set of pg_control values.
*/
@@ -489,14 +527,10 @@ GuessControlValues(void)
/*
* Create a new unique installation identifier, since we can no longer use
- * any old XLOG records. See notes in xlog.c about the algorithm.
+ * any old XLOG records.
*/
- gettimeofday(&tv, NULL);
- sysidentifier = ((uint64) tv.tv_sec) << 32;
- sysidentifier |= ((uint64) tv.tv_usec) << 12;
- sysidentifier |= getpid() & 0xFFF;
- ControlFile.system_identifier = sysidentifier;
+ ControlFile.system_identifier = GenerateSystemIdentifier();
ControlFile.checkPointCopy.redo = SizeOfXLogLongPHD;
ControlFile.checkPointCopy.ThisTimeLineID = 1;
@@ -1087,6 +1121,7 @@ usage(void)
printf(_(" -o OID set next OID\n"));
printf(_(" -O OFFSET set next multitransaction offset\n"));
printf(_(" -V, --version output version information, then exit\n"));
+ printf(_(" -s [SYSID] set system identifier (or generate one)\n"));
printf(_(" -x XID set next transaction ID\n"));
printf(_(" -?, --help show this help, then exit\n"));
printf(_("\nReport bugs to <pgsql-b...@postgresql.org>.\n"));
--
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