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Rework subtransaction commit protocol for hot standby.

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This patch eliminates the marking of subtransactions as SUBCOMMITTED in pg_clog
during their commit; instead they remain in-progress until main transaction
commit.  At main transaction commit, the commit protocol is atomic-by-page
instead of one transaction at a time.  To avoid a race condition with some
subtransactions appearing committed before others in the case where they span
more than one pg_clog page, we conserve the logic that marks them subcommitted
before marking the parent committed.

Simon Riggs with minor help from me
This commit is contained in:
Alvaro Herrera
2008-10-20 19:18:18 +00:00
parent 3afffbc902
commit 06da3c570f
7 changed files with 279 additions and 212 deletions
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5
src/include/access/clog.h
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@@ -6,7 +6,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/clog.h,v 1.21 2008/01/01 19:45:56 momjian Exp $
* $PostgreSQL: pgsql/src/include/access/clog.h,v 1.22 2008/10/20 19:18:18 alvherre Exp $
*/
#ifndef CLOG_H
#define CLOG_H
@@ -32,7 +32,8 @@ typedef int XidStatus;
#define NUM_CLOG_BUFFERS 8
extern void TransactionIdSetStatus(TransactionId xid, XidStatus status, XLogRecPtr lsn);
extern void TransactionIdSetTreeStatus(TransactionId xid, int nsubxids,
TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
extern XidStatus TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn);
extern Size CLOGShmemSize(void);

11
src/include/access/transam.h
View File

@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/access/transam.h,v 1.65 2008/03/11 20:20:35 tgl Exp $
* $PostgreSQL: pgsql/src/include/access/transam.h,v 1.66 2008/10/20 19:18:18 alvherre Exp $
*
*-------------------------------------------------------------------------
*/
@@ -139,13 +139,10 @@ extern VariableCache ShmemVariableCache;
extern bool TransactionIdDidCommit(TransactionId transactionId);
extern bool TransactionIdDidAbort(TransactionId transactionId);
extern bool TransactionIdIsKnownCompleted(TransactionId transactionId);
extern void TransactionIdCommit(TransactionId transactionId);
extern void TransactionIdAsyncCommit(TransactionId transactionId, XLogRecPtr lsn);
extern void TransactionIdAbort(TransactionId transactionId);
extern void TransactionIdSubCommit(TransactionId transactionId);
extern void TransactionIdCommitTree(int nxids, TransactionId *xids);
extern void TransactionIdAsyncCommitTree(int nxids, TransactionId *xids, XLogRecPtr lsn);
extern void TransactionIdAbortTree(int nxids, TransactionId *xids);
extern void TransactionIdCommitTree(TransactionId xid, int nxids, TransactionId *xids);
extern void TransactionIdAsyncCommitTree(TransactionId xid, int nxids, TransactionId *xids, XLogRecPtr lsn);
extern void TransactionIdAbortTree(TransactionId xid, int nxids, TransactionId *xids);
extern bool TransactionIdPrecedes(TransactionId id1, TransactionId id2);
extern bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2);
extern bool TransactionIdFollows(TransactionId id1, TransactionId id2);