8000 Add new user fn pg_current_xlog_flush_location() · bobby-lin/postgres@e63bb45 · GitHub
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Commit e63bb45

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simonat2ndQuadrantsimonat2ndQuadrant
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Add new user fn pg_current_xlog_flush_location()
Tomas Vondra, reviewed by Michael Paquier and Amit Kapila Minor edits by me
1 parent 1e29e63 commit e63bb45

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4 files changed

+41
-6
lines changed

4 files changed

+41
-6
lines changed

‎doc/src/sgml/func.sgml

Lines changed: 17 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -16788,6 +16788,9 @@ SELECT set_config('log_statement_stats', 'off', false);
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<indexterm>
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<primary>pg_create_restore_point</primary>
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</indexterm>
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<indexterm>
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<primary>pg_current_xlog_flush_location</primary>
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</indexterm>
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<indexterm>
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<primary>pg_current_xlog_insert_location</primary>
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</indexterm>
@@ -16843,6 +16846,13 @@ SELECT set_config('log_statement_stats', 'off', false);
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<entry><type>pg_lsn</type></entry>
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<entry>Create a named point for performing restore (restricted to superusers)</entry>
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</row>
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<row>
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<entry>
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<literal><function>pg_current_xlog_flush_location()</function></literal>
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</entry>
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<entry><type>pg_lsn</type></entry>
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<entry>Get current transaction log flush location</entry>
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</row>
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<row>
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<entry>
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<literal><function>pg_current_xlog_insert_location()</function></literal>
@@ -16977,13 +16987,14 @@ postgres=# select pg_start_backup('label_goes_here');
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<function>pg_current_xlog_location</> displays the current transaction log write
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location in the same format used by the above functions. Similarly,
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<function>pg_current_xlog_insert_location</> displays the current transaction log
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insertion point. The insertion point is the <quote>logical</> end
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of the transaction log
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at any instant, while the write location is the end of what has actually
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been written out from the server's internal buffers. The write location
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is the end of what can be examined from outside the server, and is usually
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insertion point and <function>pg_current_xlog_flush_location</> displays the
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current transaction log flush point. The insertion point is the <quote>logical</>
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end of the transaction log at any instant, while the write location is the end of
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what has actually been written out from the server's internal buffers and flush
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location is the location guaranteed to be written to durable storage. The write
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location is the end of what can be examined from outside the server, and is usually
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what you want if you are interested in archiving partially-complete transaction log
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files. The insertion point is made available primarily for server
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files. The insertion and flush points are made available primarily for server
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debugging purposes. These are both read-only operations and do not
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require superuser permissions.
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</para>

‎src/backend/access/transam/xlogfuncs.c

Lines changed: 21 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -215,6 +215,27 @@ pg_current_xlog_insert_location(PG_FUNCTION_ARGS)
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PG_RETURN_LSN(current_recptr);
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}
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/*
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* Report the current WAL flush location (same format as pg_start_backup etc)
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*
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* This function is mostly for debugging purposes.
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*/
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Datum
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pg_current_xlog_flush_location(PG_FUNCTION_ARGS)
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{
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XLogRecPtr current_recptr;
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if (RecoveryInProgress())
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ereport(ERROR,
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(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
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errmsg("recovery is in progress"),
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errhint("WAL control functions cannot be executed during recovery.")));
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current_recptr = GetFlushRecPtr();
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PG_RETURN_LSN(current_recptr);
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}
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/*
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* Report the last WAL receive location (same format as pg_start_backup etc)
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*

‎src/include/access/xlog_fn.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -19,6 +19,7 @@ extern Datum pg_switch_xlog(PG_FUNCTION_ARGS);
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extern Datum pg_create_restore_point(PG_FUNCTION_ARGS);
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extern Datum pg_current_xlog_location(PG_FUNCTION_ARGS);
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extern Datum pg_current_xlog_insert_location(PG_FUNCTION_ARGS);
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extern Datum pg_current_xlog_flush_location(PG_FUNCTION_ARGS);
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extern Datum pg_last_xlog_receive_location(PG_FUNCTION_ARGS);
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extern Datum pg_last_xlog_replay_location(PG_FUNCTION_ARGS);
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extern Datum pg_last_xact_replay_timestamp(PG_FUNCTION_ARGS);

‎src/include/catalog/pg_proc.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -3158,6 +3158,8 @@ DATA(insert OID = 2849 ( pg_current_xlog_location PGNSP PGUID 12 1 0 0 0 f f f f
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DESCR("current xlog write location");
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DATA(insert OID = 2852 ( pg_current_xlog_insert_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_current_xlog_insert_location _null_ _null_ _null_ ));
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DESCR("current xlog insert location");
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DATA(insert OID = 3330 ( pg_current_xlog_flush_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_current_xlog_flush_location _null_ _null_ _null_ ));
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DESCR("current xlog flush location");
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DATA(insert OID = 2850 ( pg_xlogfile_name_offset PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 2249 "3220" "{3220,25,23}" "{i,o,o}" "{wal_location,file_name,file_offset}" _null_ _null_ pg_xlogfile_name_offset _null_ _null_ _null_ ));
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DESCR("xlog filename and byte offset, given an xlog location");
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DATA(insert OID = 2851 ( pg_xlogfile_name PGNSP PGUID 12 1 0 0 0 f f f f t f i s 1 0 25 "3220" _null_ _null_ _null_ _null_ _null_ pg_xlogfile_name _null_ _null_ _null_ ));

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