database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-11-09 06:21:09 +03:00
Code Activity

Augment WAL records for btree delete with GetOldestXmin() to reduce

Browse Source 
false positives during Hot Standby conflict processing. Simple
patch to enhance conflict processing, following previous discussions.
Controlled by parameter minimize_standby_conflicts = on | off, with
default off allows measurement of performance impact to see whether
it should be set on all the time.
This commit is contained in:
Simon Riggs
2010-01-29 18:39:05 +00:00
parent d0cfc01823
commit 6d2bc0a6cf
6 changed files with 48 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
src/backend/access/nbtree/nbtpage.c
View File

@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.115 2010/01/02 16:57:35 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.116 2010/01/29 18:39:05 sriggs Exp $
*
* NOTES
* Postgres btree pages look like ordinary relation pages. The opaque
@@ -29,6 +29,7 @@
#include "storage/freespace.h"
#include "storage/indexfsm.h"
#include "storage/lmgr.h"
#include "storage/procarray.h"
#include "utils/inval.h"
#include "utils/snapmgr.h"
@@ -671,9 +672,18 @@ _bt_delitems(Relation rel, Buffer buf,
{
Page page = BufferGetPage(buf);
BTPageOpaque opaque;
TransactionId latestRemovedXid = InvalidTransactionId;
Assert(isVacuum || lastBlockVacuumed == 0);
/*
* If allowed, calculate an accurate latestRemovedXid, otherwise
* pass InvalidTransactionId which can cause false positive
* conflicts to be assessed when we replay this WAL record.
*/
if (!isVacuum && XLogStandbyInfoActive() && MinimizeStandbyConflicts)
latestRemovedXid = GetOldestXmin(false, true);
/* No ereport(ERROR) until changes are logged */
START_CRIT_SECTION();
@@ -721,13 +731,7 @@ _bt_delitems(Relation rel, Buffer buf,
xlrec_delete.node = rel->rd_node;
xlrec_delete.block = BufferGetBlockNumber(buf);
/*
* XXX: We would like to set an accurate latestRemovedXid, but
* there is no easy way of obtaining a useful value. So we punt
* and store InvalidTransactionId, which forces the standby to
* wait for/cancel all currently running transactions.
*/
xlrec_delete.latestRemovedXid = InvalidTransactionId;
xlrec_delete.latestRemovedXid = latestRemovedXid;
rdata[0].data = (char *) &xlrec_delete;
rdata[0].len = SizeOfBtreeDelete;
}