From e63bb4549a2f47b86de9fc21c9f8b00440f34f99 Mon Sep 17 00:00:00 2001 From: Simon Riggs Date: Tue, 12 Jan 2016 07:54:52 +0000 Subject: [PATCH] Add new user fn pg_current_xlog_flush_location() Tomas Vondra, reviewed by Michael Paquier and Amit Kapila Minor edits by me --- doc/src/sgml/func.sgml | 23 +++++++++++++++++------ src/backend/access/transam/xlogfuncs.c | 21 +++++++++++++++++++++ src/include/access/xlog_fn.h | 1 + src/include/catalog/pg_proc.h | 2 ++ 4 files changed, 41 insertions(+), 6 deletions(-) diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 8591aa3e5a..0af01d9f10 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -16788,6 +16788,9 @@ SELECT set_config('log_statement_stats', 'off', false); pg_create_restore_point + + pg_current_xlog_flush_location + pg_current_xlog_insert_location @@ -16843,6 +16846,13 @@ SELECT set_config('log_statement_stats', 'off', false); pg_lsn Create a named point for performing restore (restricted to superusers) + + + pg_current_xlog_flush_location() + + pg_lsn + Get current transaction log flush location + pg_current_xlog_insert_location() @@ -16977,13 +16987,14 @@ postgres=# select pg_start_backup('label_goes_here'); pg_current_xlog_location displays the current transaction log write location in the same format used by the above functions. Similarly, pg_current_xlog_insert_location displays the current transaction log - insertion point. The insertion point is the logical end - of the transaction log - at any instant, while the write location is the end of what has actually - been written out from the server's internal buffers. The write location - is the end of what can be examined from outside the server, and is usually + insertion point and pg_current_xlog_flush_location displays the + current transaction log flush point. The insertion point is the logical + end of the transaction log at any instant, while the write location is the end of + what has actually been written out from the server's internal buffers and flush + location is the location guaranteed to be written to durable storage. The write + location is the end of what can be examined from outside the server, and is usually what you want if you are interested in archiving partially-complete transaction log - files. The insertion point is made available primarily for server + files. The insertion and flush points are made available primarily for server debugging purposes. These are both read-only operations and do not require superuser permissions. diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c index 42168985e0..31cbb01ce4 100644 --- a/src/backend/access/transam/xlogfuncs.c +++ b/src/backend/access/transam/xlogfuncs.c @@ -215,6 +215,27 @@ pg_current_xlog_insert_location(PG_FUNCTION_ARGS) PG_RETURN_LSN(current_recptr); } +/* + * Report the current WAL flush location (same format as pg_start_backup etc) + * + * This function is mostly for debugging purposes. + */ +Datum +pg_current_xlog_flush_location(PG_FUNCTION_ARGS) +{ + XLogRecPtr current_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."))); + + current_recptr = GetFlushRecPtr(); + + PG_RETURN_LSN(current_recptr); +} + /* * Report the last WAL receive location (same format as pg_start_backup etc) * diff --git a/src/include/access/xlog_fn.h b/src/include/access/xlog_fn.h index 73046b0a4f..762df8bea3 100644 --- a/src/include/access/xlog_fn.h +++ b/src/include/access/xlog_fn.h @@ -19,6 +19,7 @@ extern Datum pg_switch_xlog(PG_FUNCTION_ARGS); extern Datum pg_create_restore_point(PG_FUNCTION_ARGS); extern Datum pg_current_xlog_location(PG_FUNCTION_ARGS); extern Datum pg_current_xlog_insert_location(PG_FUNCTION_ARGS); +extern Datum pg_current_xlog_flush_location(PG_FUNCTION_ARGS); extern Datum pg_last_xlog_receive_location(PG_FUNCTION_ARGS); extern Datum pg_last_xlog_replay_location(PG_FUNCTION_ARGS); extern Datum pg_last_xact_replay_timestamp(PG_FUNCTION_ARGS); diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h index 95d683c8ff..f58672e4a7 100644 --- a/src/include/catalog/pg_proc.h +++ b/src/include/catalog/pg_proc.h @@ -3158,6 +3158,8 @@ DATA(insert OID = 2849 ( pg_current_xlog_location PGNSP PGUID 12 1 0 0 0 f f f f DESCR("current xlog write location"); 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_ )); DESCR("current xlog insert location"); +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_ )); +DESCR("current xlog flush location"); 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_ )); DESCR("xlog filename and byte offset, given an xlog location"); 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_ )); -- 2.40.0