diff options
| author | Simon Riggs <simon@2ndQuadrant.com> | 2009-12-19 01:32:45 +0000 |
|---|---|---|
| committer | Simon Riggs <simon@2ndQuadrant.com> | 2009-12-19 01:32:45 +0000 |
| commit | efc16ea520679d713d98a2c7bf1453c4ff7b91ec (patch) | |
| tree | 6a39d2af0704a36281dc7df3ec10823eb3e6de75 /src/include/access/xlog_internal.h | |
| parent | 78a09145e0f8322e625bbc7d69fcb865ce4f3034 (diff) | |
Allow read only connections during recovery, known as Hot Standby.
Enabled by recovery_connections = on (default) and forcing archive recovery using a recovery.conf. Recovery processing now emulates the original transactions as they are replayed, providing full locking and MVCC behaviour for read only queries. Recovery must enter consistent state before connections are allowed, so there is a delay, typically short, before connections succeed. Replay of recovering transactions can conflict and in some cases deadlock with queries during recovery; these result in query cancellation after max_standby_delay seconds have expired. Infrastructure changes have minor effects on normal running, though introduce four new types of WAL record.
New test mode "make standbycheck" allows regression tests of static command behaviour on a standby server while in recovery. Typical and extreme dynamic behaviours have been checked via code inspection and manual testing. Few port specific behaviours have been utilised, though primary testing has been on Linux only so far.
This commit is the basic patch. Additional changes will follow in this release to enhance some aspects of behaviour, notably improved handling of conflicts, deadlock detection and query cancellation. Changes to VACUUM FULL are also required.
Simon Riggs, with significant and lengthy review by Heikki Linnakangas, including streamlined redesign of snapshot creation and two-phase commit.
Important contributions from Florian Pflug, Mark Kirkwood, Merlin Moncure, Greg Stark, Gianni Ciolli, Gabriele Bartolini, Hannu Krosing, Robert Haas, Tatsuo Ishii, Hiroyuki Yamada plus support and feedback from many other community members.
Diffstat (limited to 'src/include/access/xlog_internal.h')
| -rw-r--r-- | src/include/access/xlog_internal.h | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h index 508c2eeb8de..9747dd8c963 100644 --- a/src/include/access/xlog_internal.h +++ b/src/include/access/xlog_internal.h @@ -11,7 +11,7 @@ * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/access/xlog_internal.h,v 1.25 2009/01/01 17:23:56 momjian Exp $ + * $PostgreSQL: pgsql/src/include/access/xlog_internal.h,v 1.26 2009/12/19 01:32:42 sriggs Exp $ */ #ifndef XLOG_INTERNAL_H #define XLOG_INTERNAL_H @@ -71,7 +71,7 @@ typedef struct XLogContRecord /* * Each page of XLOG file has a header like this: */ -#define XLOG_PAGE_MAGIC 0xD063 /* can be used as WAL version indicator */ +#define XLOG_PAGE_MAGIC 0xD166 /* can be used as WAL version indicator */ typedef struct XLogPageHeaderData { @@ -255,5 +255,6 @@ extern Datum pg_current_xlog_location(PG_FUNCTION_ARGS); extern Datum pg_current_xlog_insert_location(PG_FUNCTION_ARGS); extern Datum pg_xlogfile_name_offset(PG_FUNCTION_ARGS); extern Datum pg_xlogfile_name(PG_FUNCTION_ARGS); +extern Datum pg_is_in_recovery(PG_FUNCTION_ARGS); #endif /* XLOG_INTERNAL_H */ |