Replace implementation of pg_log as a relation accessed through the

buffer manager with 'pg_clog', a specialized access method modeled
on pg_xlog.  This simplifies startup (don't need to play games to
open pg_log; among other things, OverrideTransactionSystem goes away),
should improve performance a little, and opens the door to recycling
commit log space by removing no-longer-needed segments of the commit
log.  Actual recycling is not there yet, but I felt I should commit
this part separately since it'd still be useful if we chose not to
do transaction ID wraparound.

src/include/access/clog.h

@@ -0,0 +1,47 @@
+/*
+ * clog.h
+ *
+ * PostgreSQL transaction-commit-log manager
+ *
+ * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $Id: clog.h,v 1.1 2001/08/25 18:52:42 tgl Exp $
+ */
+#ifndef CLOG_H
+#define CLOG_H
+
+#include "access/xlog.h"
+
+/*
+ * Possible transaction statuses --- note that all-zeroes is the initial
+ * state.
+ */
+typedef int XidStatus;
+
+#define TRANSACTION_STATUS_IN_PROGRESS		0x00
+#define TRANSACTION_STATUS_COMMITTED		0x01
+#define TRANSACTION_STATUS_ABORTED			0x02
+/* 0x03 is available without changing commit log space allocation */
+
+
+extern void TransactionIdSetStatus(TransactionId xid, XidStatus status);
+extern XidStatus TransactionIdGetStatus(TransactionId xid);
+
+extern int	CLOGShmemSize(void);
+extern void CLOGShmemInit(void);
+extern void BootStrapCLOG(void);
+extern void StartupCLOG(void);
+extern void ShutdownCLOG(void);
+extern void CheckPointCLOG(void);
+extern void ExtendCLOG(TransactionId newestXact);
+extern void TruncateCLOG(TransactionId oldestXact);
+
+/* XLOG stuff */
+#define CLOG_ZEROPAGE		0x00
+
+extern void clog_redo(XLogRecPtr lsn, XLogRecord *record);
+extern void clog_undo(XLogRecPtr lsn, XLogRecord *record);
+extern void clog_desc(char *buf, uint8 xl_info, char *rec);
+
+#endif	 /* CLOG_H */

src/include/access/rmgr.h

@@ -1,9 +1,9 @@
 /*
- *
  * rmgr.h
  *
  * Resource managers definition
  *
+ * $Id: rmgr.h,v 1.6 2001/08/25 18:52:42 tgl Exp $
  */
 #ifndef RMGR_H
 #define RMGR_H
@@ -16,6 +16,7 @@ typedef uint8 RmgrId;
 #define RM_XLOG_ID				0
 #define RM_XACT_ID				1
 #define RM_SMGR_ID				2
+#define RM_CLOG_ID				3
 #define RM_HEAP_ID				10
 #define RM_BTREE_ID				11
 #define RM_HASH_ID				12

src/include/access/transam.h

@@ -7,33 +7,30 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: transam.h,v 1.38 2001/08/23 23:06:38 tgl Exp $
+ * $Id: transam.h,v 1.39 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef TRANSAM_H
 #define TRANSAM_H
 
-#include "storage/bufmgr.h"
+#include "storage/spin.h"
 
 
 /* ----------------
  *		Special transaction ID values
  *
- * We do not use any transaction IDs less than 512 --- this leaves the first
- * 128 bytes of pg_log available for special purposes such as version number
- * storage.  (Currently, we do not actually use them for anything.)
- *
- * BootstrapTransactionId is the XID for "bootstrap" operations.  It should
+ * BootstrapTransactionId is the XID for "bootstrap" operations, and
+ * FrozenTransactionId is used for very old tuples.  Both should
  * always be considered valid.
  *
  * FirstNormalTransactionId is the first "normal" transaction id.
  * ----------------
  */
 #define InvalidTransactionId		((TransactionId) 0)
-#define DisabledTransactionId		((TransactionId) 1)
-#define BootstrapTransactionId		((TransactionId) 512)
-#define FirstNormalTransactionId	((TransactionId) 514)
+#define BootstrapTransactionId		((TransactionId) 1)
+#define FrozenTransactionId			((TransactionId) 2)
+#define FirstNormalTransactionId	((TransactionId) 3)
 
 /* ----------------
  *		transaction ID manipulation macros
@@ -56,19 +53,6 @@
 			(dest) = FirstNormalTransactionId; \
 	} while(0)
 
-/* ----------------
- *		transaction status values
- *
- *		someday we will use "11" = 3 = XID_COMMIT_CHILD to mean the
- *		commiting of child xactions.
- * ----------------
- */
-#define XID_INPROGRESS		0	/* transaction in progress */
-#define XID_ABORT			1	/* transaction aborted */
-#define XID_COMMIT			2	/* transaction commited */
-#define XID_COMMIT_CHILD	3	/* child xact commited */
-
-typedef unsigned char XidStatus;	/* (2 bits) */
 
 /* ----------
  *		Object ID (OID) zero is InvalidOid.
@@ -116,25 +100,15 @@ typedef VariableCacheData *VariableCache;
 /*
  * prototypes for functions in transam/transam.c
  */
-extern void InitializeTransactionLog(void);
+extern void AmiTransactionOverride(bool flag);
 extern bool TransactionIdDidCommit(TransactionId transactionId);
 extern bool TransactionIdDidAbort(TransactionId transactionId);
 extern void TransactionIdCommit(TransactionId transactionId);
 extern void TransactionIdAbort(TransactionId transactionId);
 
-/* in transam/transsup.c */
-extern void AmiTransactionOverride(bool flag);
-extern void TransComputeBlockNumber(Relation relation,
-			  TransactionId transactionId, BlockNumber *blockNumberOutP);
-extern XidStatus TransBlockNumberGetXidStatus(Relation relation,
-				BlockNumber blockNumber, TransactionId xid, bool *failP);
-extern void TransBlockNumberSetXidStatus(Relation relation,
-		   BlockNumber blockNumber, TransactionId xid, XidStatus xstatus,
-							 bool *failP);
-
 /* in transam/varsup.c */
-extern void GetNewTransactionId(TransactionId *xid);
-extern void ReadNewTransactionId(TransactionId *xid);
+extern TransactionId GetNewTransactionId(void);
+extern TransactionId ReadNewTransactionId(void);
 extern Oid	GetNewObjectId(void);
 extern void CheckMaxObjectId(Oid assigned_oid);
 
@@ -143,9 +117,6 @@ extern void CheckMaxObjectId(Oid assigned_oid);
  * ----------------
  */
 
-/* in transam.c */
-extern Relation LogRelation;
-
 /* in xact.c */
 extern bool AMI_OVERRIDE;
 

src/include/access/xact.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: xact.h,v 1.34 2001/07/12 04:11:13 tgl Exp $
+ * $Id: xact.h,v 1.35 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,7 +54,6 @@ typedef TransactionStateData *TransactionState;
 #define TRANS_INPROGRESS		2
 #define TRANS_COMMIT			3
 #define TRANS_ABORT				4
-#define TRANS_DISABLED			5
 
 /* ----------------
  *		transaction block states
@@ -100,7 +99,6 @@ extern int	TransactionFlushEnabled(void);
 extern void SetTransactionFlushEnabled(bool state);
 
 extern bool IsAbortedTransactionBlockState(void);
-extern void OverrideTransactionSystem(bool flag);
 extern TransactionId GetCurrentTransactionId(void);
 extern CommandId GetCurrentCommandId(void);
 extern CommandId GetScanCommandId(void);
@@ -110,7 +108,6 @@ extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern bool CommandIdIsCurrentCommandId(CommandId cid);
 extern bool CommandIdGEScanCommandId(CommandId cid);
 extern void CommandCounterIncrement(void);
-extern void InitializeTransactionSystem(void);
 extern void StartTransactionCommand(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);

src/include/access/xlog.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: xlog.h,v 1.24 2001/07/19 02:12:35 tgl Exp $
+ * $Id: xlog.h,v 1.25 2001/08/25 18:52:42 tgl Exp $
  */
 #ifndef XLOG_H
 #define XLOG_H
@@ -14,6 +14,7 @@
 #include "access/rmgr.h"
 #include "access/transam.h"
 #include "access/xlogdefs.h"
+#include "storage/bufmgr.h"
 #include "utils/pg_crc.h"
 
 

src/include/access/xlogdefs.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: xlogdefs.h,v 1.3 2001/03/22 04:00:32 momjian Exp $
+ * $Id: xlogdefs.h,v 1.4 2001/08/25 18:52:42 tgl Exp $
  */
 #ifndef XLOG_DEFS_H
 #define XLOG_DEFS_H
@@ -52,7 +52,7 @@ typedef struct XLogRecPtr
 
 /*
  * StartUpID (SUI) - system startups counter. It's to allow removing
- * pg_log after shutdown, in future.
+ * pg_clog after shutdown, in future.
  */
 typedef uint32 StartUpID;
 

src/include/access/xlogutils.h

@@ -6,20 +6,20 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: xlogutils.h,v 1.7 2001/03/22 04:00:32 momjian Exp $
+ * $Id: xlogutils.h,v 1.8 2001/08/25 18:52:42 tgl Exp $
  */
 #ifndef XLOG_UTILS_H
 #define XLOG_UTILS_H
 
 #include "access/rmgr.h"
+#include "storage/buf.h"
+#include "storage/itemptr.h"
 #include "utils/rel.h"
 
 extern int XLogIsOwnerOfTuple(RelFileNode hnode, ItemPointer iptr,
 				   TransactionId xid, CommandId cid);
 extern bool XLogIsValidTuple(RelFileNode hnode, ItemPointer iptr);
 
-extern void XLogOpenLogRelation(void);
-
 extern void XLogInitRelationCache(void);
 extern void XLogCloseRelationCache(void);