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Allow read only connections during recovery, known as Hot Standby.

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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.
This commit is contained in:
Simon Riggs
2009-12-19 01:32:45 +00:00
parent 78a09145e0
commit efc16ea520
87 changed files with 6165 additions and 428 deletions
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20
src/include/access/htup.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.107 2009/06/11 14:49:08 momjian Exp $
* $PostgreSQL: pgsql/src/include/access/htup.h,v 1.108 2009/12/19 01:32:42 sriggs Exp $
*
*-------------------------------------------------------------------------
*/
@@ -580,6 +580,7 @@ typedef HeapTupleData *HeapTuple;
#define XLOG_HEAP2_FREEZE 0x00
#define XLOG_HEAP2_CLEAN 0x10
#define XLOG_HEAP2_CLEAN_MOVE 0x20
#define XLOG_HEAP2_CLEANUP_INFO 0x30
/*
* All what we need to find changed tuple
@@ -668,6 +669,7 @@ typedef struct xl_heap_clean
{
RelFileNode node;
BlockNumber block;
TransactionId latestRemovedXid;
uint16 nredirected;
uint16 ndead;
/* OFFSET NUMBERS FOLLOW */
@@ -675,6 +677,19 @@ typedef struct xl_heap_clean
#define SizeOfHeapClean (offsetof(xl_heap_clean, ndead) + sizeof(uint16))
/*
* Cleanup_info is required in some cases during a lazy VACUUM.
* Used for reporting the results of HeapTupleHeaderAdvanceLatestRemovedXid()
* see vacuumlazy.c for full explanation
*/
typedef struct xl_heap_cleanup_info
{
RelFileNode node;
TransactionId latestRemovedXid;
} xl_heap_cleanup_info;
#define SizeOfHeapCleanupInfo (sizeof(xl_heap_cleanup_info))
/* This is for replacing a page's contents in toto */
/* NB: this is used for indexes as well as heaps */
typedef struct xl_heap_newpage
@@ -718,6 +733,9 @@ typedef struct xl_heap_freeze
#define SizeOfHeapFreeze (offsetof(xl_heap_freeze, cutoff_xid) + sizeof(TransactionId))
extern void HeapTupleHeaderAdvanceLatestRemovedXid(HeapTupleHeader tuple,
TransactionId *latestRemovedXid);
/* HeapTupleHeader functions implemented in utils/time/combocid.c */
extern CommandId HeapTupleHeaderGetCmin(HeapTupleHeader tup);
extern CommandId HeapTupleHeaderGetCmax(HeapTupleHeader tup);