database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-09 22:41:56 +03:00
Code Activity

Replace max_standby_delay with two parameters, max_standby_archive_delay and

Browse Source 
max_standby_streaming_delay, and revise the implementation to avoid assuming
that timestamps found in WAL records can meaningfully be compared to clock
time on the standby server.  Instead, the delay limits are compared to the
elapsed time since we last obtained a new WAL segment from archive or since
we were last "caught up" to WAL data arriving via streaming replication.
This avoids problems with clock skew between primary and standby, as well
as other corner cases that the original coding would misbehave in, such
as the primary server having significant idle time between transactions.
Per my complaint some time ago and considerable ensuing discussion.

Do some desultory editing on the hot standby documentation, too.
This commit is contained in:
Tom Lane
2010-07-03 20:43:58 +00:00
parent e6a7416e28
commit e76c1a0f4d
12 changed files with 503 additions and 358 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
src/include/access/xlog.h
View File

@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.113 2010/06/17 16:41:25 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.114 2010/07/03 20:43:58 tgl Exp $
*/
#ifndef XLOG_H
#define XLOG_H
@ -135,22 +135,25 @@ typedef struct XLogRecData
extern PGDLLIMPORT TimeLineID ThisTimeLineID; /* current TLI */
/*
* Prior to 8.4, all activity during recovery was carried out by Startup
* Prior to 8.4, all activity during recovery was carried out by the startup
* process. This local variable continues to be used in many parts of the
* code to indicate actions taken by RecoveryManagers. Other processes who
* potentially perform work during recovery should check RecoveryInProgress()
* see XLogCtl notes in xlog.c
* code to indicate actions taken by RecoveryManagers. Other processes that
* potentially perform work during recovery should check RecoveryInProgress().
* See XLogCtl notes in xlog.c.
*/
extern bool InRecovery;
/*
* Like InRecovery, standbyState is only valid in the startup process.
* In all other processes it will have the value STANDBY_DISABLED (so
* InHotStandby will read as FALSE).
*
* In DISABLED state, we're performing crash recovery or hot standby was
* disabled in recovery.conf.
*
* In INITIALIZED state, we haven't yet received a RUNNING_XACTS or shutdown
* checkpoint record to initialize our master transaction tracking system.
* In INITIALIZED state, we've run InitRecoveryTransactionEnvironment, but
* we haven't yet processed a RUNNING_XACTS or shutdown-checkpoint WAL record
* to initialize our master-transaction tracking system.
*
* When the transaction tracking is initialized, we enter the SNAPSHOT_PENDING
* state. The tracked information might still be incomplete, so we can't allow
@ -168,6 +171,7 @@ typedef enum
STANDBY_SNAPSHOT_PENDING,
STANDBY_SNAPSHOT_READY
} HotStandbyState;
extern HotStandbyState standbyState;
#define InHotStandby (standbyState >= STANDBY_SNAPSHOT_PENDING)
@ -193,7 +197,6 @@ extern int XLogArchiveTimeout;
extern bool XLogArchiveMode;
extern char *XLogArchiveCommand;
extern bool EnableHotStandby;
extern int MaxStandbyDelay;
extern bool log_checkpoints;
/* WAL levels */
@ -279,7 +282,7 @@ extern void issue_xlog_fsync(int fd, uint32 log, uint32 seg);
extern bool RecoveryInProgress(void);
extern bool XLogInsertAllowed(void);
extern TimestampTz GetLatestXLogTime(void);
extern void GetXLogReceiptTime(TimestampTz *rtime, bool *fromStream);
extern void UpdateControlFile(void);
extern uint64 GetSystemIdentifier(void);