Support an optional asynchronous commit mode, in which we don't flush WAL

before reporting a transaction committed. Data consistency is still guaranteed (unlike setting fsync = off), but a crash may lose the effects of the last few transactions. Patch by Simon, some editorialization by Tom.
2025-10-27 00:12:01 +03:00 · 2007-08-01 22:45:09 +00:00
parent c722628a43
commit 4a78cdeb6b
25 changed files with 998 additions and 303 deletions
--- a/src/include/access/clog.h
+++ b/src/include/access/clog.h
@@ -6,7 +6,7 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/clog.h,v 1.19 2007/01/05 22:19:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/clog.h,v 1.20 2007/08/01 22:45:09 tgl Exp $
 */
 #ifndef CLOG_H
 #define CLOG_H
@@ -32,8 +32,8 @@ typedef int XidStatus;
 #define NUM_CLOG_BUFFERS	8


-extern void TransactionIdSetStatus(TransactionId xid, XidStatus status);
-extern XidStatus TransactionIdGetStatus(TransactionId xid);
+extern void TransactionIdSetStatus(TransactionId xid, XidStatus status, XLogRecPtr lsn);
+extern XidStatus TransactionIdGetStatus(TransactionId xid, XLogRecPtr *lsn);

 extern Size CLOGShmemSize(void);
 extern void CLOGShmemInit(void);
--- a/src/include/access/gist_private.h
+++ b/src/include/access/gist_private.h
@@ -7,7 +7,7 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.26 2007/01/20 18:43:35 neilc Exp $
+ * $PostgreSQL: pgsql/src/include/access/gist_private.h,v 1.27 2007/08/01 22:45:09 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -200,8 +200,6 @@ typedef struct GistSplitVector
 								 * distributed between left and right pages */
 } GistSplitVector;

-#define XLogRecPtrIsInvalid( r )	( (r).xlogid == 0 && (r).xrecoff == 0 )
-
 typedef struct
 {
 	Relation	r;
--- a/src/include/access/slru.h
+++ b/src/include/access/slru.h
@@ -6,13 +6,14 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/slru.h,v 1.20 2007/01/05 22:19:51 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/slru.h,v 1.21 2007/08/01 22:45:09 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
 #ifndef SLRU_H
 #define SLRU_H

+#include "access/xlogdefs.h"
 #include "storage/lwlock.h"


@@ -51,6 +52,17 @@ typedef struct SlruSharedData
 	int		   *page_lru_count;
 	LWLockId   *buffer_locks;

+	/*
+	 * Optional array of WAL flush LSNs associated with entries in the SLRU
+	 * pages.  If not zero/NULL, we must flush WAL before writing pages (true
+	 * for pg_clog, false for multixact and pg_subtrans).  group_lsn[] has
+	 * lsn_groups_per_page entries per buffer slot, each containing the
+	 * highest LSN known for a contiguous group of SLRU entries on that slot's
+	 * page.
+	 */
+	XLogRecPtr *group_lsn;
+	int			lsn_groups_per_page;
+
 	/*----------
 	 * We mark a page "most recently used" by setting
 	 *		page_lru_count[slotno] = ++cur_lru_count;
@@ -81,8 +93,8 @@ typedef struct SlruCtlData
 	SlruShared	shared;

 	/*
-	 * This flag tells whether to fsync writes (true for pg_clog, false for
-	 * pg_subtrans).
+	 * This flag tells whether to fsync writes (true for pg_clog and multixact
+	 * stuff, false for pg_subtrans).
 	 */
 	bool		do_fsync;

@@ -106,11 +118,12 @@ typedef SlruCtlData *SlruCtl;
 typedef struct SlruFlushData *SlruFlush;


-extern Size SimpleLruShmemSize(int nslots);
-extern void SimpleLruInit(SlruCtl ctl, const char *name, int nslots,
+extern Size SimpleLruShmemSize(int nslots, int nlsns);
+extern void SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns,
 			  LWLockId ctllock, const char *subdir);
 extern int	SimpleLruZeroPage(SlruCtl ctl, int pageno);
-extern int	SimpleLruReadPage(SlruCtl ctl, int pageno, TransactionId xid);
+extern int	SimpleLruReadPage(SlruCtl ctl, int pageno, bool write_ok,
+							  TransactionId xid);
 extern int SimpleLruReadPage_ReadOnly(SlruCtl ctl, int pageno,
 						   TransactionId xid);
 extern void SimpleLruWritePage(SlruCtl ctl, int slotno, SlruFlush fdata);
--- a/src/include/access/transam.h
+++ b/src/include/access/transam.h
@@ -7,13 +7,15 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/transam.h,v 1.60 2007/01/05 22:19:51 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/transam.h,v 1.61 2007/08/01 22:45:09 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
 #ifndef TRANSAM_H
 #define TRANSAM_H

+#include "access/xlogdefs.h"
+

 /* ----------------
 *		Special transaction ID values
@@ -115,14 +117,17 @@ extern VariableCache ShmemVariableCache;
 extern bool TransactionIdDidCommit(TransactionId transactionId);
 extern bool TransactionIdDidAbort(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 bool TransactionIdPrecedes(TransactionId id1, TransactionId id2);
 extern bool TransactionIdPrecedesOrEquals(TransactionId id1, TransactionId id2);
 extern bool TransactionIdFollows(TransactionId id1, TransactionId id2);
 extern bool TransactionIdFollowsOrEquals(TransactionId id1, TransactionId id2);
+extern XLogRecPtr TransactionIdGetCommitLSN(TransactionId xid);

 /* in transam/varsup.c */
 extern TransactionId GetNewTransactionId(bool isSubXact);
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -7,7 +7,7 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/xact.h,v 1.87 2007/04/30 21:01:53 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/xact.h,v 1.88 2007/08/01 22:45:09 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -41,6 +41,9 @@ extern int	XactIsoLevel;
 extern bool DefaultXactReadOnly;
 extern bool XactReadOnly;

+/* Asynchronous commits */
+extern bool XactSyncCommit;
+
 /*
 *	start- and end-of-transaction callbacks for dynamically loaded modules
 */
@@ -147,6 +150,7 @@ extern void SetCurrentStatementStartTimestamp(void);
 extern int	GetCurrentTransactionNestLevel(void);
 extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern void CommandCounterIncrement(void);
+extern void ForceSyncCommit(void);
 extern void StartTransactionCommand(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -6,7 +6,7 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.81 2007/07/24 04:54:09 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.82 2007/08/01 22:45:09 tgl Exp $
 */
 #ifndef XLOG_H
 #define XLOG_H
@@ -197,8 +197,11 @@ extern CheckpointStatsData CheckpointStats;
 extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
 extern void XLogFlush(XLogRecPtr RecPtr);
 extern void XLogBackgroundFlush(void);
+extern void XLogAsyncCommitFlush(void);
 extern bool XLogNeedsFlush(XLogRecPtr RecPtr);

+extern void XLogSetAsyncCommitLSN(XLogRecPtr record);
+
 extern void xlog_redo(XLogRecPtr lsn, XLogRecord *record);
 extern void xlog_desc(StringInfo buf, uint8 xl_info, char *rec);

--- a/src/include/access/xlogdefs.h
+++ b/src/include/access/xlogdefs.h
@@ -7,7 +7,7 @@
 * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
- * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.17 2007/02/14 05:00:40 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.18 2007/08/01 22:45:09 tgl Exp $
 */
 #ifndef XLOG_DEFS_H
 #define XLOG_DEFS_H
@@ -33,6 +33,8 @@ typedef struct XLogRecPtr
 	uint32		xrecoff;		/* byte offset of location in log file */
 } XLogRecPtr;

+#define XLogRecPtrIsInvalid(r)	((r).xrecoff == 0)
+

 /*
 * Macros for comparing XLogRecPtrs