On 27.02.2016 22:36, Yury Zhuravlev wrote:
Hello.
You forgot to declare a GetXLogOldestLSNPtr function in a header file
(in xlog.h I think).
Some compilers refuse to compile this code (MSVC for example). Now I
see warning from GCC:
xlog.c:10627:1: warning: no previous prototype for
«GetXLogOldestLSNPtr» [-Wmissing-prototypes]
GetXLogOldestLSNPtr(void)
Thanks.
Hi Yury,
thank for valuable remark.
Changes applied
--
Ivan Kartyshov
Postgres Professional: www.postgrespro.com
Russian Postgres Company
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index f9eea76..f774233 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -16908,6 +16908,8 @@ SELECT set_config('log_statement_stats', 'off', false);
</indexterm>
<indexterm>
<primary>pg_current_xlog_location</primary>
+ <indexterm>
+ <primary>pg_oldest_xlog_location</primary>
</indexterm>
<indexterm>
<primary>pg_start_backup</primary>
@@ -16981,6 +16983,13 @@ SELECT set_config('log_statement_stats', 'off', false);
</row>
<row>
<entry>
+ <literal><function>pg_oldest_xlog_location()</function></literal>
+ </entry>
+ <entry><type>pg_lsn</type></entry>
+ <entry>Get the oldest WAL LSN (log sequence number)</entry>
+ </row>
+ <row>
+ <entry>
<literal><function>pg_start_backup(<parameter>label</> <type>text</> <optional>, <parameter>fast</> <type>boolean</> </optional>)</function></literal>
</entry>
<entry><type>pg_lsn</type></entry>
@@ -17096,6 +17105,7 @@ postgres=# select pg_start_backup('label_goes_here');
</para>
<para>
+ <function>pg_oldest_xlog_location</> displays the oldest WAL LSN.
<function>pg_current_xlog_location</> displays the current transaction log write
location in the same format used by the above functions. Similarly,
<function>pg_current_xlog_insert_location</> displays the current transaction log
diff --git a/doc/src/sgml/high-availability.sgml b/doc/src/sgml/high-availability.sgml
index 6cb690c..5a0e887 100644
--- a/doc/src/sgml/high-availability.sgml
+++ b/doc/src/sgml/high-availability.sgml
@@ -860,6 +860,8 @@ primary_conninfo = 'host=192.168.1.50 port=5432 user=foo password=foopass'
The last WAL receive location in the standby is also displayed in the
process status of the WAL receiver process, displayed using the
<command>ps</> command (see <xref linkend="monitoring-ps"> for details).
+ Also we can get the oldest WAL LSN (Log Sequence Number)
+ <function>pg_oldest_xlog_location</>, it can give us a useful tool for DBA, additionally it can show us, if xlog replication or wal-sender is working properly or indicate if replication on startup can can get up to date with master, or after long turnoff must be recovered from archive.
</para>
<para>
You can retrieve a list of WAL sender processes via the
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 94b79ac..067d51c 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -10669,6 +10669,18 @@ GetXLogWriteRecPtr(void)
}
/*
+ * Get oldest WAL write pointer
+ */
+XLogRecPtr
+GetXLogOldestLSNPtr(void)
+{
+ XLogRecPtr result;
+
+ XLogSegNoOffsetToRecPtr(XLogGetLastRemovedSegno()+1, 1, result);
+ return result;
+}
+
+/*
* Returns the redo pointer of the last checkpoint or restartpoint. This is
* the oldest point in WAL that we still need, if we have to restart recovery.
*/
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 31cbb01..44e01e1 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -195,6 +195,27 @@ pg_current_xlog_location(PG_FUNCTION_ARGS)
}
/*
+ * Report the oldest WAL write location (same format as pg_start_backup etc)
+ *
+ * This is useful for determining the first LSN in existing sequences
+ */
+Datum
+pg_oldest_xlog_location(PG_FUNCTION_ARGS)
+{
+ XLogRecPtr oldest_recptr;
+
+ if (RecoveryInProgress())
+ ereport(ERROR,
+ (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+ errmsg("recovery is in progress"),
+ errhint("WAL control functions cannot be executed during recovery.")));
+
+ oldest_recptr = GetXLogOldestLSNPtr();
+
+ PG_RETURN_LSN(oldest_recptr);
+}
+
+/*
* Report the current WAL insert location (same format as pg_start_backup etc)
*
* This function is mostly for debugging purposes.
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index ecd30ce..bc7ce6c 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -236,6 +236,7 @@ extern void GetXLogReceiptTime(TimestampTz *rtime, bool *fromStream);
extern XLogRecPtr GetXLogReplayRecPtr(TimeLineID *replayTLI);
extern XLogRecPtr GetXLogInsertRecPtr(void);
extern XLogRecPtr GetXLogWriteRecPtr(void);
+extern XLogRecPtr GetXLogOldestLSNPtr(void);
extern bool RecoveryIsPaused(void);
extern void SetRecoveryPause(bool recoveryPause);
extern TimestampTz GetLatestXTime(void);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index b24e434..3c2cefb 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -5202,6 +5202,10 @@ DESCR("get an individual replication origin's replication progress");
DATA(insert OID = 6014 ( pg_show_replication_origin_status PGNSP PGUID 12 1 100 0 0 f f f f f t v r 0 0 2249 "" "{26,25,3220,3220}" "{o,o,o,o}" "{local_id, external_id, remote_lsn, local_lsn}" _null_ _null_ pg_show_replication_origin_status _null_ _null_ _null_ ));
DESCR("get progress for all replication origins");
+
+DATA(insert OID = 6015 ( pg_oldest_xlog_location PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 3220 "" _null_ _null_ _null_ _null_ _null_ pg_oldest_xlog_location _null_ _null_ _null_ ));
+DESCR("pg oldest xlog location");
+
/* rls */
DATA(insert OID = 3298 ( row_security_active PGNSP PGUID 12 1 0 0 0 f f f f t f s s 1 0 16 "26" _null_ _null_ _null_ _null_ _null_ row_security_active _null_ _null_ _null_ ));
DESCR("row security for current context active on table by table oid");
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