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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
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
/*
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* clog.h
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*
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* PostgreSQL transaction-commit-log manager
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*
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* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/access/clog.h,v 1.22 2008/10/20 19:18:18 alvherre Exp $
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*/
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#ifndef CLOG_H
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#define CLOG_H
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#include "access/xlog.h"
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/*
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* Possible transaction statuses --- note that all-zeroes is the initial
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* state.
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*
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* A "subcommitted" transaction is a committed subtransaction whose parent
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* hasn't committed or aborted yet.
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*/
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typedef int XidStatus;
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#define TRANSACTION_STATUS_IN_PROGRESS 0x00
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#define TRANSACTION_STATUS_COMMITTED 0x01
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#define TRANSACTION_STATUS_ABORTED 0x02
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#define TRANSACTION_STATUS_SUB_COMMITTED 0x03
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/* Number of SLRU buffers to use for clog */
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#define NUM_CLOG_BUFFERS 8
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extern void TransactionIdSetTreeStatus(TransactionId xid, int nsubxids,
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TransactionId *subxids, XidStatus status, XLogRecPtr lsn);
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extern XidStatus TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn);
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extern Size CLOGShmemSize(void);
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extern void CLOGShmemInit(void);
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extern void BootStrapCLOG(void);
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extern void StartupCLOG(void);
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extern void ShutdownCLOG(void);
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extern void CheckPointCLOG(void);
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extern void ExtendCLOG(TransactionId newestXact);
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extern void TruncateCLOG(TransactionId oldestXact);
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/* XLOG stuff */
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#define CLOG_ZEROPAGE 0x00
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#define CLOG_TRUNCATE 0x10
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extern void clog_redo(XLogRecPtr lsn, XLogRecord *record);
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extern void clog_desc(StringInfo buf, uint8 xl_info, char *rec);
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#endif /* CLOG_H */
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