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.

37 files changed, 1240 insertions, 1120 deletions

diff --git a/src/backend/access/transam/Makefile b/src/backend/access/transam/Makefile
index c4adcc5bffa..b34c01ef899 100644
--- a/src/backend/access/transam/Makefile
+++ b/src/backend/access/transam/Makefile
@@ -4,7 +4,7 @@
 #    Makefile for access/transam
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/backend/access/transam/Makefile,v 1.14 2001/08/24 14:07:48 petere Exp $
+#    $Header: /cvsroot/pgsql/src/backend/access/transam/Makefile,v 1.15 2001/08/25 18:52:41 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -12,7 +12,7 @@ subdir = src/backend/access/transam
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global
 
-OBJS = transam.o transsup.o varsup.o xact.o xid.o xlog.o xlogutils.o rmgr.o
+OBJS = clog.o transam.o varsup.o xact.o xid.o xlog.o xlogutils.o rmgr.o
 
 all: SUBSYS.o
 
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
new file mode 100644
index 00000000000..2347edfd095
--- /dev/null
+++ b/src/backend/access/transam/clog.c
@@ -0,0 +1,987 @@
+/*-------------------------------------------------------------------------
+ *
+ * clog.c
+ *		PostgreSQL transaction-commit-log manager
+ *
+ * This module replaces the old "pg_log" access code, which treated pg_log
+ * essentially like a relation, in that it went through the regular buffer
+ * manager.  The problem with that was that there wasn't any good way to
+ * recycle storage space for transactions so old that they'll never be
+ * looked up again.  Now we use specialized access code so that the commit
+ * log can be broken into relatively small, independent segments.
+ *
+ * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/clog.c,v 1.1 2001/08/25 18:52:41 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include <fcntl.h>
+#include <dirent.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "access/clog.h"
+#include "storage/s_lock.h"
+#include "miscadmin.h"
+
+
+/*
+ * Defines for CLOG page and segment sizes.  A page is the same BLCKSZ
+ * as is used everywhere else in Postgres.  The CLOG segment size can be
+ * chosen somewhat arbitrarily; we make it 1 million transactions by default,
+ * or 256Kb.
+ *
+ * Note: because TransactionIds are 32 bits and wrap around at 0xFFFFFFFF,
+ * CLOG page numbering also wraps around at 0xFFFFFFFF/CLOG_XACTS_PER_PAGE,
+ * and CLOG segment numbering at 0xFFFFFFFF/CLOG_XACTS_PER_SEGMENT.  We need
+ * take no explicit notice of that fact in this module, except when comparing
+ * segment and page numbers in TruncateCLOG (see CLOGPagePrecedes).
+ */
+
+#define CLOG_BLCKSZ			BLCKSZ
+
+/* We need two bits per xact, so four xacts fit in a byte */
+#define CLOG_BITS_PER_XACT	2
+#define CLOG_XACTS_PER_BYTE	4
+#define CLOG_XACTS_PER_PAGE	(CLOG_BLCKSZ * CLOG_XACTS_PER_BYTE)
+#define CLOG_XACT_BITMASK	((1 << CLOG_BITS_PER_XACT) - 1)
+
+#define CLOG_XACTS_PER_SEGMENT	0x100000
+#define CLOG_PAGES_PER_SEGMENT	(CLOG_XACTS_PER_SEGMENT / CLOG_XACTS_PER_PAGE)
+
+#define TransactionIdToPage(xid)	((xid) / (TransactionId) CLOG_XACTS_PER_PAGE)
+#define TransactionIdToPgIndex(xid)	((xid) % (TransactionId) CLOG_XACTS_PER_PAGE)
+#define TransactionIdToByte(xid)	(TransactionIdToPgIndex(xid) / CLOG_XACTS_PER_BYTE)
+#define TransactionIdToBIndex(xid)	((xid) % (TransactionId) CLOG_XACTS_PER_BYTE)
+
+
+/*----------
+ * Shared-memory data structures for CLOG control
+ *
+ * We use a simple least-recently-used scheme to manage a pool of page
+ * buffers for the CLOG.  Under ordinary circumstances we expect that write
+ * traffic will occur mostly to the latest CLOG page (and to the just-prior
+ * page, soon after a page transition).  Read traffic will probably touch
+ * a larger span of pages, but in any case a fairly small number of page
+ * buffers should be sufficient.  So, we just search the buffers using plain
+ * linear search; there's no need for a hashtable or anything fancy.
+ * The management algorithm is straight LRU except that we will never swap
+ * out the latest page (since we know it's going to be hit again eventually).
+ *
+ * We use an overall spinlock to protect the shared data structures, plus
+ * per-buffer spinlocks that synchronize I/O for each buffer.  A process
+ * that is reading in or writing out a page buffer does not hold the control
+ * lock, only the per-buffer lock for the buffer it is working on.
+ *
+ * To change the page number or state of a buffer, one must normally hold
+ * the control lock.  (The sole exception to this rule is that a writer
+ * process changes the state from DIRTY to WRITE_IN_PROGRESS while holding
+ * only the per-buffer lock.)  If the buffer's state is neither EMPTY nor
+ * CLEAN, then there may be processes doing (or waiting to do) I/O on the
+ * buffer, so the page number may not be changed, and the only allowed state
+ * transition is to change WRITE_IN_PROGRESS to DIRTY after dirtying the page.
+ * To do any other state transition involving a buffer with potential I/O
+ * processes, one must hold both the per-buffer lock and the control lock.
+ * (Note the control lock must be acquired second; do not wait on a buffer
+ * lock while holding the control lock.)  A process wishing to read a page
+ * marks the buffer state as READ_IN_PROGRESS, then drops the control lock,
+ * acquires the per-buffer lock, and rechecks the state before proceeding.
+ * This recheck takes care of the possibility that someone else already did
+ * the read, while the early marking prevents someone else from trying to
+ * read the same page into a different buffer.
+ *
+ * Note we are assuming that read and write of the state value is atomic,
+ * since I/O processes may examine and change the state while not holding
+ * the control lock.
+ *
+ * As with the regular buffer manager, it is possible for another process
+ * to re-dirty a page that is currently being written out.  This is handled
+ * by setting the page's state from WRITE_IN_PROGRESS to DIRTY.  The writing
+ * process must notice this and not mark the page CLEAN when it's done.
+ *
+ * XXX it's probably okay to use a spinlock for the control lock, since
+ * that lock is only held for very short operations.  It'd be nice to use
+ * some other form of lock for the per-buffer I/O locks, however.
+ *
+ * XLOG interactions: this module generates an XLOG record whenever a new
+ * CLOG page is initialized to zeroes.  Other writes of CLOG come from
+ * recording of transaction commit or abort in xact.c, which generates its
+ * own XLOG records for these events and will re-perform the status update
+ * on redo; so we need make no additional XLOG entry here.  Also, the XLOG
+ * is guaranteed flushed through the XLOG commit record before we are called
+ * to log a commit, so the WAL rule "write xlog before data" is satisfied
+ * automatically for commits, and we don't really care for aborts.  Therefore,
+ * we don't need to mark XLOG pages with LSN information; we have enough
+ * synchronization already.
+ *----------
+ */
+#define NUM_CLOG_BUFFERS	8
+
+typedef enum
+{
+	CLOG_PAGE_EMPTY,			/* CLOG buffer is not in use */
+	CLOG_PAGE_READ_IN_PROGRESS,	/* CLOG page is being read in */
+	CLOG_PAGE_CLEAN,			/* CLOG page is valid and not dirty */
+	CLOG_PAGE_DIRTY,			/* CLOG page is valid but needs write */
+	CLOG_PAGE_WRITE_IN_PROGRESS	/* CLOG page is being written out in */
+} ClogPageStatus;
+
+/*
+ * Shared-memory state for CLOG.
+ */
+typedef struct ClogCtlData
+{
+	/*
+	 * Info for each buffer slot.  Page number is undefined when status is
+	 * EMPTY.  lru_count is essentially the number of operations since last
+	 * use of this page; the page with highest lru_count is the best candidate
+	 * to replace.
+	 */
+	char	   *page_buffer[NUM_CLOG_BUFFERS];
+	ClogPageStatus	page_status[NUM_CLOG_BUFFERS];
+	int			page_number[NUM_CLOG_BUFFERS];
+	unsigned int	page_lru_count[NUM_CLOG_BUFFERS];
+	/*
+	 * latest_page_number is the page number of the current end of the
+	 * CLOG; this is not critical data, since we use it only to avoid
+	 * swapping out the latest page.
+	 */
+	int			latest_page_number;
+
+	slock_t		control_lck;	/* Lock for ClogCtlData itself */
+	slock_t		buffer_lck[NUM_CLOG_BUFFERS]; /* Per-buffer I/O locks */
+} ClogCtlData;
+
+static ClogCtlData *ClogCtl = NULL;
+
+/*
+ * ClogDir is set during CLOGShmemInit and does not change thereafter.
+ * The value is automatically inherited by backends via fork, and
+ * doesn't need to be in shared memory.
+ */
+static char ClogDir[MAXPGPATH];
+
+#define ClogFileName(path, seg)	\
+	snprintf(path, MAXPGPATH, "%s/%04X", ClogDir, seg)
+
+/*
+ * Macro to mark a buffer slot "most recently used".
+ */
+#define ClogRecentlyUsed(slotno)	\
+	do { \
+		int		iilru; \
+		for (iilru = 0; iilru < NUM_CLOG_BUFFERS; iilru++) \
+			ClogCtl->page_lru_count[iilru]++; \
+		ClogCtl->page_lru_count[slotno] = 0; \
+	} while (0)
+
+
+static int	ZeroCLOGPage(int pageno, bool writeXlog);
+static int	ReadCLOGPage(int pageno);
+static void WriteCLOGPage(int slotno);
+static void CLOGPhysicalReadPage(int pageno, int slotno);
+static void CLOGPhysicalWritePage(int pageno, int slotno);
+static int	SelectLRUCLOGPage(int pageno);
+static bool ScanCLOGDirectory(int cutoffPage, bool doDeletions);
+static bool CLOGPagePrecedes(int page1, int page2);
+static void WriteZeroPageXlogRec(int pageno);
+
+
+/*
+ * Record the final state of a transaction in the commit log.
+ *
+ * NB: this is a low-level routine and is NOT the preferred entry point
+ * for most uses; TransactionLogUpdate() in transam.c is the intended caller.
+ */
+void
+TransactionIdSetStatus(TransactionId xid, XidStatus status)
+{
+	int			pageno = TransactionIdToPage(xid);
+	int			byteno = TransactionIdToByte(xid);
+	int			bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
+	int			slotno;
+	char	   *byteptr;
+
+	Assert(status == TRANSACTION_STATUS_COMMITTED ||
+		   status == TRANSACTION_STATUS_ABORTED);
+
+	S_LOCK(&(ClogCtl->control_lck));
+
+	slotno = ReadCLOGPage(pageno);
+	byteptr = ClogCtl->page_buffer[slotno] + byteno;
+
+	/* Current state should be 0 or target state */
+	Assert(((*byteptr >> bshift) & CLOG_XACT_BITMASK) == 0 ||
+		   ((*byteptr >> bshift) & CLOG_XACT_BITMASK) == status);
+
+	*byteptr |= (status << bshift);
+
+	ClogCtl->page_status[slotno] = CLOG_PAGE_DIRTY;
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+}
+
+/*
+ * Interrogate the state of a transaction in the commit log.
+ *
+ * NB: this is a low-level routine and is NOT the preferred entry point
+ * for most uses; TransactionLogTest() in transam.c is the intended caller.
+ */
+XidStatus
+TransactionIdGetStatus(TransactionId xid)
+{
+	int			pageno = TransactionIdToPage(xid);
+	int			byteno = TransactionIdToByte(xid);
+	int			bshift = TransactionIdToBIndex(xid) * CLOG_BITS_PER_XACT;
+	int			slotno;
+	char	   *byteptr;
+	XidStatus	status;
+
+	S_LOCK(&(ClogCtl->control_lck));
+
+	slotno = ReadCLOGPage(pageno);
+	byteptr = ClogCtl->page_buffer[slotno] + byteno;
+
+	status = (*byteptr >> bshift) & CLOG_XACT_BITMASK;
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+
+	return status;
+}
+
+
+/*
+ * Initialization of shared memory for CLOG
+ */
+
+int
+CLOGShmemSize(void)
+{
+	return MAXALIGN(sizeof(ClogCtlData) + CLOG_BLCKSZ * NUM_CLOG_BUFFERS);
+}
+
+void
+CLOGShmemInit(void)
+{
+	bool		found;
+	char	   *bufptr;
+	int			slotno;
+
+	/* this must agree with space requested by CLOGShmemSize() */
+	ClogCtl = (ClogCtlData *)
+		ShmemInitStruct("CLOG Ctl",
+						MAXALIGN(sizeof(ClogCtlData) +
+								 CLOG_BLCKSZ * NUM_CLOG_BUFFERS),
+						&found);
+	Assert(!found);
+
+	memset(ClogCtl, 0, sizeof(ClogCtlData));
+
+	S_INIT_LOCK(&(ClogCtl->control_lck));
+
+	bufptr = ((char *) ClogCtl) + sizeof(ClogCtlData);
+
+	for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
+	{
+		ClogCtl->page_buffer[slotno] = bufptr;
+		ClogCtl->page_status[slotno] = CLOG_PAGE_EMPTY;
+		S_INIT_LOCK(&(ClogCtl->buffer_lck[slotno]));
+		bufptr += CLOG_BLCKSZ;
+	}
+
+	/* ClogCtl->latest_page_number will be set later */
+
+	/* Init CLOG directory path */
+	snprintf(ClogDir, MAXPGPATH, "%s/pg_clog", DataDir);
+}
+
+/*
+ * This func must be called ONCE on system install.  It creates
+ * the initial CLOG segment.  (The CLOG directory is assumed to
+ * have been created by the initdb shell script, and CLOGShmemInit
+ * must have been called already.)
+ */
+void
+BootStrapCLOG(void)
+{
+	int			slotno;
+
+	S_LOCK(&(ClogCtl->control_lck));
+
+	/* Create and zero the first page of the commit log */
+	slotno = ZeroCLOGPage(0, false);
+
+	/* Make sure it's written out */
+	WriteCLOGPage(slotno);
+	Assert(ClogCtl->page_status[slotno] == CLOG_PAGE_CLEAN);
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+}
+
+/*
+ * Initialize (or reinitialize) a page of CLOG to zeroes.
+ * If writeXlog is TRUE, also emit an XLOG record saying we did this.
+ *
+ * The page is not actually written, just set up in shared memory.
+ * The slot number of the new page is returned.
+ *
+ * Control lock must be held at entry, and will be held at exit.
+ */
+static int
+ZeroCLOGPage(int pageno, bool writeXlog)
+{
+	int			slotno;
+
+	/* Find a suitable buffer slot for the page */
+	slotno = SelectLRUCLOGPage(pageno);
+	Assert(ClogCtl->page_status[slotno] == CLOG_PAGE_EMPTY ||
+		   ClogCtl->page_status[slotno] == CLOG_PAGE_CLEAN ||
+		   ClogCtl->page_number[slotno] == pageno);
+
+	/* Mark the slot as containing this page */
+	ClogCtl->page_number[slotno] = pageno;
+	ClogCtl->page_status[slotno] = CLOG_PAGE_DIRTY;
+	ClogRecentlyUsed(slotno);
+
+	/* Set the buffer to zeroes */
+	MemSet(ClogCtl->page_buffer[slotno], 0, CLOG_BLCKSZ);
+
+	/* Assume this page is now the latest active page */
+	ClogCtl->latest_page_number = pageno;
+
+	if (writeXlog)
+		WriteZeroPageXlogRec(pageno);
+
+	return slotno;
+}
+
+/*
+ * Find a CLOG page in a shared buffer, reading it in if necessary.
+ * The page number must correspond to an already-initialized page.
+ *
+ * Return value is the shared-buffer slot number now holding the page.
+ * The buffer's LRU access info is updated.
+ *
+ * Control lock must be held at entry, and will be held at exit.
+ */
+static int
+ReadCLOGPage(int pageno)
+{
+	/* Outer loop handles restart if we lose the buffer to someone else */
+	for (;;)
+	{
+		int			slotno;
+
+		/* See if page already is in memory; if not, pick victim slot */
+		slotno = SelectLRUCLOGPage(pageno);
+
+		/* Did we find the page in memory? */
+		if (ClogCtl->page_number[slotno] == pageno &&
+			ClogCtl->page_status[slotno] != CLOG_PAGE_EMPTY)
+		{
+			/* If page is still being read in, we cannot use it yet */
+			if (ClogCtl->page_status[slotno] != CLOG_PAGE_READ_IN_PROGRESS)
+			{
+				/* otherwise, it's ready to use */
+				ClogRecentlyUsed(slotno);
+				return slotno;
+			}
+		}
+		else
+		{
+			/* We found no match; assert we selected a freeable slot */
+			Assert(ClogCtl->page_status[slotno] == CLOG_PAGE_EMPTY ||
+				   ClogCtl->page_status[slotno] == CLOG_PAGE_CLEAN);
+		}
+
+		/* Mark the slot read-busy (no-op if it already was) */
+		ClogCtl->page_number[slotno] = pageno;
+		ClogCtl->page_status[slotno] = CLOG_PAGE_READ_IN_PROGRESS;
+
+		/*
+		 * Temporarily mark page as recently-used to discourage
+		 * SelectLRUCLOGPage from selecting it again for someone else.
+		 */
+		ClogCtl->page_lru_count[slotno] = 0;
+
+		/* Release shared lock, grab per-buffer lock instead */
+		S_UNLOCK(&(ClogCtl->control_lck));
+		S_LOCK(&(ClogCtl->buffer_lck[slotno]));
+
+		/*
+		 * Check to see if someone else already did the read, or took the
+		 * buffer away from us.  If so, restart from the top.
+		 */
+		if (ClogCtl->page_number[slotno] != pageno ||
+			ClogCtl->page_status[slotno] != CLOG_PAGE_READ_IN_PROGRESS)
+		{
+			S_UNLOCK(&(ClogCtl->buffer_lck[slotno]));
+			S_LOCK(&(ClogCtl->control_lck));
+			continue;
+		}
+
+		/* Okay, do the read */
+		CLOGPhysicalReadPage(pageno, slotno);
+
+		/* Re-acquire shared control lock and update page state */
+		S_LOCK(&(ClogCtl->control_lck));
+
+		Assert(ClogCtl->page_number[slotno] == pageno &&
+			   ClogCtl->page_status[slotno] == CLOG_PAGE_READ_IN_PROGRESS);
+
+		ClogCtl->page_status[slotno] = CLOG_PAGE_CLEAN;
+
+		S_UNLOCK(&(ClogCtl->buffer_lck[slotno]));
+
+		ClogRecentlyUsed(slotno);
+		return slotno;
+	}
+}
+
+/*
+ * Write a CLOG page from a shared buffer, if necessary.
+ * Does nothing if the specified slot is not dirty.
+ *
+ * NOTE: only one write attempt is made here.  Hence, it is possible that
+ * the page is still dirty at exit (if someone else re-dirtied it during
+ * the write).  However, we *do* attempt a fresh write even if the page
+ * is already being written; this is for checkpoints.
+ *
+ * Control lock must be held at entry, and will be held at exit.
+ */
+static void
+WriteCLOGPage(int slotno)
+{
+	int pageno;
+
+	/* Do nothing if page does not need writing */
+	if (ClogCtl->page_status[slotno] != CLOG_PAGE_DIRTY &&
+		ClogCtl->page_status[slotno] != CLOG_PAGE_WRITE_IN_PROGRESS)
+		return;
+
+	pageno = ClogCtl->page_number[slotno];
+
+	/* Release shared lock, grab per-buffer lock instead */
+	S_UNLOCK(&(ClogCtl->control_lck));
+	S_LOCK(&(ClogCtl->buffer_lck[slotno]));
+
+	/*
+	 * Check to see if someone else already did the write, or took the
+	 * buffer away from us.  If so, do nothing.  NOTE: we really should
+	 * never see WRITE_IN_PROGRESS here, since that state should only
+	 * occur while the writer is holding the buffer lock.  But accept it
+	 * so that we have a recovery path if a writer aborts.
+	 */
+	if (ClogCtl->page_number[slotno] != pageno ||
+		(ClogCtl->page_status[slotno] != CLOG_PAGE_DIRTY &&
+		 ClogCtl->page_status[slotno] != CLOG_PAGE_WRITE_IN_PROGRESS))
+	{
+		S_UNLOCK(&(ClogCtl->buffer_lck[slotno]));
+		S_LOCK(&(ClogCtl->control_lck));
+		return;
+	}
+
+	/*
+	 * Mark the slot write-busy.  After this point, a transaction status
+	 * update on this page will mark it dirty again.  NB: we are assuming
+	 * that read/write of the page status field is atomic, since we change
+	 * the state while not holding control lock.  However, we cannot set
+	 * this state any sooner, or we'd possibly fool a previous writer
+	 * into thinking he's successfully dumped the page when he hasn't.
+	 * (Scenario: other writer starts, page is redirtied, we come along and
+	 * set WRITE_IN_PROGRESS again, other writer completes and sets CLEAN
+	 * because redirty info has been lost, then we think it's clean too.)
+	 */
+	ClogCtl->page_status[slotno] = CLOG_PAGE_WRITE_IN_PROGRESS;
+
+	/* Okay, do the write */
+	CLOGPhysicalWritePage(pageno, slotno);
+
+	/* Re-acquire shared control lock and update page state */
+	S_LOCK(&(ClogCtl->control_lck));
+
+	Assert(ClogCtl->page_number[slotno] == pageno &&
+		   (ClogCtl->page_status[slotno] == CLOG_PAGE_WRITE_IN_PROGRESS ||
+			ClogCtl->page_status[slotno] == CLOG_PAGE_DIRTY));
+
+	/* Cannot set CLEAN if someone re-dirtied page since write started */
+	if (ClogCtl->page_status[slotno] == CLOG_PAGE_WRITE_IN_PROGRESS)
+		ClogCtl->page_status[slotno] = CLOG_PAGE_CLEAN;
+
+	S_UNLOCK(&(ClogCtl->buffer_lck[slotno]));
+}
+
+/*
+ * Physical read of a (previously existing) page into a buffer slot
+ *
+ * For now, assume it's not worth keeping a file pointer open across
+ * read/write operations.  We could cache one virtual file pointer ...
+ */
+static void
+CLOGPhysicalReadPage(int pageno, int slotno)
+{
+	int			segno =   pageno / CLOG_PAGES_PER_SEGMENT;
+	int			rpageno = pageno % CLOG_PAGES_PER_SEGMENT;
+	int			offset = rpageno * CLOG_BLCKSZ;
+	char		path[MAXPGPATH];
+	int			fd;
+
+	ClogFileName(path, segno);
+
+	/*
+	 * In a crash-and-restart situation, it's possible for us to receive
+	 * commands to set the commit status of transactions whose bits are
+	 * in already-truncated segments of the commit log (see notes in
+	 * CLOGPhysicalWritePage).  Hence, if we are InRecovery, allow the
+	 * case where the file doesn't exist, and return zeroes instead.
+	 */
+	fd = BasicOpenFile(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
+	if (fd < 0)
+	{
+		if (errno != ENOENT || !InRecovery)
+			elog(STOP, "open of %s failed: %m", path);
+		elog(DEBUG, "clog file %s doesn't exist, reading as zeroes", path);
+		MemSet(ClogCtl->page_buffer[slotno], 0, CLOG_BLCKSZ);
+		return;
+	}
+
+	if (lseek(fd, (off_t) offset, SEEK_SET) < 0)
+		elog(STOP, "lseek of clog file %u, offset %u failed: %m",
+			 segno, offset);
+
+	errno = 0;
+	if (read(fd, ClogCtl->page_buffer[slotno], CLOG_BLCKSZ) != CLOG_BLCKSZ)
+		elog(STOP, "read of clog file %u, offset %u failed: %m",
+			 segno, offset);
+
+	close(fd);
+}
+
+/*
+ * Physical write of a page from a buffer slot
+ *
+ * For now, assume it's not worth keeping a file pointer open across
+ * read/write operations.  We could cache one virtual file pointer ...
+ */
+static void
+CLOGPhysicalWritePage(int pageno, int slotno)
+{
+	int			segno =   pageno / CLOG_PAGES_PER_SEGMENT;
+	int			rpageno = pageno % CLOG_PAGES_PER_SEGMENT;
+	int			offset = rpageno * CLOG_BLCKSZ;
+	char		path[MAXPGPATH];
+	int			fd;
+
+	ClogFileName(path, segno);
+
+	/*
+	 * If the file doesn't already exist, we should create it.  It is possible
+	 * for this to need to happen when writing a page that's not first in
+	 * its segment; we assume the OS can cope with that.  (Note: it might seem
+	 * that it'd be okay to create files only when ZeroCLOGPage is called for
+	 * the first page of a segment.  However, if after a crash and restart
+	 * the REDO logic elects to replay the log from a checkpoint before the
+	 * latest one, then it's possible that we will get commands to set
+	 * transaction status of transactions that have already been truncated
+	 * from the commit log.  Easiest way to deal with that is to accept
+	 * references to nonexistent files here and in CLOGPhysicalReadPage.)
+	 */
+	fd = BasicOpenFile(path, O_RDWR | PG_BINARY, S_IRUSR | S_IWUSR);
+	if (fd < 0)
+	{
+		if (errno != ENOENT)
+			elog(STOP, "open of %s failed: %m", path);
+		fd = BasicOpenFile(path, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
+						   S_IRUSR | S_IWUSR);
+		if (fd < 0)
+			elog(STOP, "creation of file %s failed: %m", path);
+	}
+
+	if (lseek(fd, (off_t) offset, SEEK_SET) < 0)
+		elog(STOP, "lseek of clog file %u, offset %u failed: %m",
+			 segno, offset);
+
+	errno = 0;
+	if (write(fd, ClogCtl->page_buffer[slotno], CLOG_BLCKSZ) != CLOG_BLCKSZ)
+	{
+		/* if write didn't set errno, assume problem is no disk space */
+		if (errno == 0)
+			errno = ENOSPC;
+		elog(STOP, "write of clog file %u, offset %u failed: %m",
+			 segno, offset);
+	}
+
+	close(fd);
+}
+
+/*
+ * Select the slot to re-use when we need a free slot.
+ *
+ * The target page number is passed because we need to consider the
+ * possibility that some other process reads in the target page while
+ * we are doing I/O to free a slot.  Hence, check or recheck to see if
+ * any slot already holds the target page, and return that slot if so.
+ * Thus, the returned slot is *either* a slot already holding the pageno
+ * (could be any state except EMPTY), *or* a freeable slot (state EMPTY
+ * or CLEAN).
+ *
+ * Control lock must be held at entry, and will be held at exit.
+ */
+static int
+SelectLRUCLOGPage(int pageno)
+{
+	/* Outer loop handles restart after I/O */
+	for (;;)
+	{
+		int			slotno;
+		int			bestslot = 0;
+		unsigned int bestcount = 0;
+
+		/* See if page already has a buffer assigned */
+		for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
+		{
+			if (ClogCtl->page_number[slotno] == pageno &&
+				ClogCtl->page_status[slotno] != CLOG_PAGE_EMPTY)
+				return slotno;
+		}
+
+		/*
+		 * If we find any EMPTY slot, just select that one.
+		 * Else locate the least-recently-used slot that isn't the
+		 * latest CLOG page.
+		 */
+		for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
+		{
+			if (ClogCtl->page_status[slotno] == CLOG_PAGE_EMPTY)
+				return slotno;
+			if (ClogCtl->page_lru_count[slotno] > bestcount &&
+				ClogCtl->page_number[slotno] != ClogCtl->latest_page_number)
+			{
+				bestslot = slotno;
+				bestcount = ClogCtl->page_lru_count[slotno];
+			}
+		}
+
+		/*
+		 * If the selected page is clean, we're set.
+		 */
+		if (ClogCtl->page_status[bestslot] == CLOG_PAGE_CLEAN)
+			return bestslot;
+
+		/*
+		 * We need to do I/O.  Normal case is that we have to write it out,
+		 * but it's possible in the worst case to have selected a read-busy
+		 * page.  In that case we use ReadCLOGPage to wait for the read to
+		 * complete.
+		 */
+		if (ClogCtl->page_status[bestslot] == CLOG_PAGE_READ_IN_PROGRESS)
+			(void) ReadCLOGPage(ClogCtl->page_number[bestslot]);
+		else
+			WriteCLOGPage(bestslot);
+
+		/*
+		 * Now loop back and try again.  This is the easiest way of dealing
+		 * with corner cases such as the victim page being re-dirtied while
+		 * we wrote it.
+		 */
+	}
+}
+
+/*
+ * This must be called ONCE during postmaster or standalone-backend startup,
+ * after StartupXLOG has initialized ShmemVariableCache->nextXid.
+ */
+void
+StartupCLOG(void)
+{
+	/*
+	 * Initialize our idea of the latest page number.
+	 */
+	ClogCtl->latest_page_number = TransactionIdToPage(ShmemVariableCache->nextXid);
+}
+
+/*
+ * This must be called ONCE during postmaster or standalone-backend shutdown
+ */
+void
+ShutdownCLOG(void)
+{
+	int			slotno;
+
+	S_LOCK(&(ClogCtl->control_lck));
+
+	for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
+	{
+		WriteCLOGPage(slotno);
+		Assert(ClogCtl->page_status[slotno] == CLOG_PAGE_EMPTY ||
+			   ClogCtl->page_status[slotno] == CLOG_PAGE_CLEAN);
+	}
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+}
+
+/*
+ * Perform a checkpoint --- either during shutdown, or on-the-fly
+ */
+void
+CheckPointCLOG(void)
+{
+	int			slotno;
+
+	S_LOCK(&(ClogCtl->control_lck));
+
+	for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
+	{
+		WriteCLOGPage(slotno);
+		/*
+		 * We cannot assert that the slot is clean now, since another
+		 * process might have re-dirtied it already.  That's okay.
+		 */
+	}
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+}
+
+
+/*
+ * Make sure that CLOG has room for a newly-allocated XID.
+ *
+ * NB: this is called while holding XidGenLock.  We want it to be very fast
+ * most of the time; even when it's not so fast, no actual I/O need happen
+ * unless we're forced to write out a dirty clog or xlog page to make room
+ * in shared memory.
+ */
+void
+ExtendCLOG(TransactionId newestXact)
+{
+	int			pageno;
+
+	/* No work except at first XID of a page */
+	if (TransactionIdToPgIndex(newestXact) != 0)
+		return;
+
+	pageno = TransactionIdToPage(newestXact);
+
+	S_LOCK(&(ClogCtl->control_lck));
+
+	/* Zero the page and make an XLOG entry about it */
+	ZeroCLOGPage(pageno, true);
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+}
+
+
+/*
+ * Remove all CLOG segments before the one holding the passed transaction ID
+ *
+ * When this is called, we know that the database logically contains no
+ * reference to transaction IDs older than oldestXact.  However, we must
+ * not truncate the CLOG until we have performed a checkpoint, to ensure
+ * that no such references remain on disk either; else a crash just after
+ * the truncation might leave us with a problem.  Since CLOG segments hold
+ * a large number of transactions, the opportunity to actually remove a
+ * segment is fairly rare, and so it seems best not to do the checkpoint
+ * unless we have confirmed that there is a removable segment.  Therefore
+ * we issue the checkpoint command here, not in higher-level code as might
+ * seem cleaner.
+ */
+void
+TruncateCLOG(TransactionId oldestXact)
+{
+	int			cutoffPage;
+	int			slotno;
+
+	/*
+	 * The cutoff point is the start of the segment containing oldestXact.
+	 */
+	oldestXact -= oldestXact % CLOG_XACTS_PER_SEGMENT;
+	cutoffPage = TransactionIdToPage(oldestXact);
+
+	if (!ScanCLOGDirectory(cutoffPage, false))
+		return;					/* nothing to remove */
+
+	/* Perform a CHECKPOINT */
+	CreateCheckPoint(false);
+
+	/*
+	 * Scan CLOG shared memory and remove any pages preceding the cutoff
+	 * page, to ensure we won't rewrite them later.  (Any dirty pages
+	 * should have been flushed already during the checkpoint, we're
+	 * just being extra careful here.)
+	 */
+	S_LOCK(&(ClogCtl->control_lck));
+
+restart:;
+
+	for (slotno = 0; slotno < NUM_CLOG_BUFFERS; slotno++)
+	{
+		if (ClogCtl->page_status[slotno] == CLOG_PAGE_EMPTY)
+			continue;
+		if (!CLOGPagePrecedes(ClogCtl->page_number[slotno], cutoffPage))
+			continue;
+		/*
+		 * If page is CLEAN, just change state to EMPTY (expected case).
+		 */
+		if (ClogCtl->page_status[slotno] == CLOG_PAGE_CLEAN)
+		{
+			ClogCtl->page_status[slotno] = CLOG_PAGE_EMPTY;
+			continue;
+		}
+		/*
+		 * Hmm, we have (or may have) I/O operations acting on the page,
+		 * so we've got to wait for them to finish and then start again.
+		 * This is the same logic as in SelectLRUCLOGPage.
+		 */
+		if (ClogCtl->page_status[slotno] == CLOG_PAGE_READ_IN_PROGRESS)
+			(void) ReadCLOGPage(ClogCtl->page_number[slotno]);
+		else
+			WriteCLOGPage(slotno);
+		goto restart;
+	}
+
+	S_UNLOCK(&(ClogCtl->control_lck));
+
+	/* Now we can remove the old CLOG segment(s) */
+	(void) ScanCLOGDirectory(cutoffPage, true);
+}
+
+/*
+ * TruncateCLOG subroutine: scan CLOG directory for removable segments.
+ * Actually remove them iff doDeletions is true.  Return TRUE iff any
+ * removable segments were found.  Note: no locking is needed.
+ */
+static bool
+ScanCLOGDirectory(int cutoffPage, bool doDeletions)
+{
+	bool		found = false;
+	DIR		   *cldir;
+	struct dirent *clde;
+	int			segno;
+	int			segpage;
+	char		path[MAXPGPATH];
+
+	cldir = opendir(ClogDir);
+	if (cldir == NULL)
+		elog(STOP, "could not open transaction-commit log directory (%s): %m",
+			 ClogDir);
+
+	errno = 0;
+	while ((clde = readdir(cldir)) != NULL)
+	{
+		if (strlen(clde->d_name) == 4 &&
+			strspn(clde->d_name, "0123456789ABCDEF") == 4)
+		{
+			segno = (int) strtol(clde->d_name, NULL, 16);
+			segpage = segno * CLOG_PAGES_PER_SEGMENT;
+			if (CLOGPagePrecedes(segpage, cutoffPage))
+			{
+				found = true;
+				if (doDeletions)
+				{
+					snprintf(path, MAXPGPATH, "%s/%s", ClogDir, clde->d_name);
+					unlink(path);
+				}
+			}
+		}
+		errno = 0;
+	}
+	if (errno)
+		elog(STOP, "could not read transaction-commit log directory (%s): %m",
+			 ClogDir);
+	closedir(cldir);
+
+	return found;
+}
+
+/*
+ * Decide which of two CLOG page numbers is "older" for truncation purposes.
+ *
+ * We need to use comparison of TransactionIds here in order to do the right
+ * thing with wraparound XID arithmetic.  However, if we are asked about
+ * page number zero, we don't want to hand InvalidTransactionId to
+ * TransactionIdPrecedes: it'll get weird about permanent xact IDs.  So,
+ * offset both xids by FirstNormalTransactionId to avoid that.
+ */
+static bool
+CLOGPagePrecedes(int page1, int page2)
+{
+	TransactionId xid1;
+	TransactionId xid2;
+
+	xid1 = (TransactionId) page1 * CLOG_XACTS_PER_PAGE;
+	xid1 += FirstNormalTransactionId;
+	xid2 = (TransactionId) page2 * CLOG_XACTS_PER_PAGE;
+	xid2 += FirstNormalTransactionId;
+
+	return TransactionIdPrecedes(xid1, xid2);
+}
+
+
+/*
+ * Write a ZEROPAGE xlog record
+ *
+ * Note: xlog record is marked as outside transaction control, since we
+ * want it to be redone whether the invoking transaction commits or not.
+ * (Besides which, this is normally done just before entering a transaction.)
+ */
+static void
+WriteZeroPageXlogRec(int pageno)
+{
+	XLogRecData rdata;
+
+	rdata.buffer = InvalidBuffer;
+	rdata.data = (char *) (&pageno);
+	rdata.len = sizeof(int);
+	rdata.next = NULL;
+	(void) XLogInsert(RM_CLOG_ID, CLOG_ZEROPAGE | XLOG_NO_TRAN, &rdata);
+}
+
+/*
+ * CLOG resource manager's routines
+ */
+void
+clog_redo(XLogRecPtr lsn, XLogRecord *record)
+{
+	uint8		info = record->xl_info & ~XLR_INFO_MASK;
+
+	if (info == CLOG_ZEROPAGE)
+	{
+		int		pageno;
+		int		slotno;
+
+		memcpy(&pageno, XLogRecGetData(record), sizeof(int));
+
+		S_LOCK(&(ClogCtl->control_lck));
+
+		slotno = ZeroCLOGPage(pageno, false);
+		WriteCLOGPage(slotno);
+		Assert(ClogCtl->page_status[slotno] == CLOG_PAGE_CLEAN);
+
+		S_UNLOCK(&(ClogCtl->control_lck));
+	}
+}
+
+void
+clog_undo(XLogRecPtr lsn, XLogRecord *record)
+{
+}
+
+void
+clog_desc(char *buf, uint8 xl_info, char *rec)
+{
+	uint8		info = xl_info & ~XLR_INFO_MASK;
+
+	if (info == CLOG_ZEROPAGE)
+	{
+		int		pageno;
+
+		memcpy(&pageno, rec, sizeof(int));
+		sprintf(buf + strlen(buf), "zeropage: %d", pageno);
+	}
+	else
+		strcat(buf, "UNKNOWN");
+}
diff --git a/src/backend/access/transam/rmgr.c b/src/backend/access/transam/rmgr.c
index 625b0db3202..b9af3a06c97 100644
--- a/src/backend/access/transam/rmgr.c
+++ b/src/backend/access/transam/rmgr.c
@@ -1,4 +1,13 @@
+/*
+ * rmgr.c
+ *
+ * Resource managers definition
+ *
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/rmgr.c,v 1.9 2001/08/25 18:52:41 tgl Exp $
+ */
 #include "postgres.h"
+
+#include "access/clog.h"
 #include "access/gist.h"
 #include "access/hash.h"
 #include "access/heapam.h"
@@ -9,11 +18,12 @@
 #include "storage/smgr.h"
 #include "commands/sequence.h"
 
+
 RmgrData	RmgrTable[] = {
 	{"XLOG", xlog_redo, xlog_undo, xlog_desc},
 	{"Transaction", xact_redo, xact_undo, xact_desc},
 	{"Storage", smgr_redo, smgr_undo, smgr_desc},
-	{"Reserved 3", NULL, NULL, NULL},
+	{"CLOG", clog_redo, clog_undo, clog_desc},
 	{"Reserved 4", NULL, NULL, NULL},
 	{"Reserved 5", NULL, NULL, NULL},
 	{"Reserved 6", NULL, NULL, NULL},
diff --git a/src/backend/access/transam/transam.c b/src/backend/access/transam/transam.c
index 65718b4cae9..3364ed66337 100644
--- a/src/backend/access/transam/transam.c
+++ b/src/backend/access/transam/transam.c
@@ -1,14 +1,14 @@
 /*-------------------------------------------------------------------------
  *
  * transam.c
- *	  postgres transaction log/time interface routines
+ *	  postgres transaction log interface routines
  *
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.46 2001/08/23 23:06:37 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.47 2001/08/25 18:52:41 tgl Exp $
  *
  * NOTES
  *	  This file contains the high level access-method interface to the
@@ -19,76 +19,27 @@
 
 #include "postgres.h"
 
-#include "access/heapam.h"
+#include "access/clog.h"
 #include "access/transam.h"
-#include "catalog/catname.h"
-#include "miscadmin.h"
 
 
-static int	RecoveryCheckingEnabled(void);
-static void TransRecover(Relation logRelation);
 static bool TransactionLogTest(TransactionId transactionId, XidStatus status);
 static void TransactionLogUpdate(TransactionId transactionId,
 					 XidStatus status);
 
 /* ----------------
- *	  global variables holding pointers to relations used
- *	  by the transaction system.  These are initialized by
- *	  InitializeTransactionLog().
- * ----------------
- */
-
-Relation	LogRelation = (Relation) NULL;
-
-/* ----------------
  *		Single-item cache for results of TransactionLogTest.
  * ----------------
  */
 static TransactionId cachedTestXid = InvalidTransactionId;
 static XidStatus	cachedTestXidStatus;
 
-/* ----------------
- *		transaction recovery state variables
- *
- *		When the transaction system is initialized, we may
- *		need to do recovery checking.  This decision is decided
- *		by the postmaster or the user by supplying the backend
- *		with a special flag.  In general, we want to do recovery
- *		checking whenever we are running without a postmaster
- *		or when the number of backends running under the postmaster
- *		goes from zero to one. -cim 3/21/90
- * ----------------
- */
-static int		RecoveryCheckingEnableState = 0;
-
-/* ----------------
- *		recovery checking accessors
- * ----------------
- */
-static int
-RecoveryCheckingEnabled(void)
-{
-	return RecoveryCheckingEnableState;
-}
-
-#ifdef NOT_USED
-static void
-SetRecoveryCheckingEnabled(bool state)
-{
-	RecoveryCheckingEnableState = (state == true);
-}
-
-#endif
 
 /* ----------------------------------------------------------------
  *		postgres log access method interface
  *
  *		TransactionLogTest
  *		TransactionLogUpdate
- *		========
- *		   these functions do work for the interface
- *		   functions - they search/retrieve and append/update
- *		   information in the log and time relations.
  * ----------------------------------------------------------------
  */
 
@@ -102,59 +53,42 @@ static bool						/* true/false: does transaction id have
 TransactionLogTest(TransactionId transactionId, /* transaction id to test */
 				   XidStatus status)	/* transaction status */
 {
-	BlockNumber blockNumber;
 	XidStatus	xidstatus;		/* recorded status of xid */
-	bool		fail = false;	/* success/failure */
-
-	/*
-	 * during initialization consider all transactions as having been
-	 * committed
-	 */
-	if (!RelationIsValid(LogRelation))
-		return (bool) (status == XID_COMMIT);
 
 	/*
-	 * before going to the buffer manager, check our single item cache to
+	 * Before going to the commit log manager, check our single item cache to
 	 * see if we didn't just check the transaction status a moment ago.
 	 */
 	if (TransactionIdEquals(transactionId, cachedTestXid))
-		return (bool)
-			(status == cachedTestXidStatus);
+		return (status == cachedTestXidStatus);
 
 	/*
-	 * compute the item pointer corresponding to the page containing our
-	 * transaction id.	We save the item in our cache to speed up things
-	 * if we happen to ask for the same xid's status more than once.
+	 * Also, check to see if the transaction ID is a permanent one.
 	 */
-	TransComputeBlockNumber(LogRelation, transactionId, &blockNumber);
-	xidstatus = TransBlockNumberGetXidStatus(LogRelation,
-											 blockNumber,
-											 transactionId,
-											 &fail);
-
-	if (!fail)
+	if (! TransactionIdIsNormal(transactionId))
 	{
-
-		/*
-		 * DO NOT cache status for transactions in unknown state !!!
-		 */
-		if (xidstatus == XID_COMMIT || xidstatus == XID_ABORT)
-		{
-			TransactionIdStore(transactionId, &cachedTestXid);
-			cachedTestXidStatus = xidstatus;
-		}
-		return (bool) (status == xidstatus);
+		if (TransactionIdEquals(transactionId, BootstrapTransactionId))
+			return (status == TRANSACTION_STATUS_COMMITTED);
+		if (TransactionIdEquals(transactionId, FrozenTransactionId))
+			return (status == TRANSACTION_STATUS_COMMITTED);
+		return (status == TRANSACTION_STATUS_ABORTED);
 	}
 
 	/*
-	 * here the block didn't contain the information we wanted
+	 * Get the status.
 	 */
-	elog(ERROR, "TransactionLogTest: failed to get xidstatus");
+	 xidstatus = TransactionIdGetStatus(transactionId);
 
-	/*
-	 * so lint is happy...
-	 */
-	return false;
+	 /*
+	  * DO NOT cache status for unfinished transactions!
+	  */
+	 if (xidstatus != TRANSACTION_STATUS_IN_PROGRESS)
+	 {
+		 TransactionIdStore(transactionId, &cachedTestXid);
+		 cachedTestXidStatus = xidstatus;
+	 }
+
+	 return (status == xidstatus);
 }
 
 /* --------------------------------
@@ -165,24 +99,10 @@ static void
 TransactionLogUpdate(TransactionId transactionId,		/* trans id to update */
 					 XidStatus status)	/* new trans status */
 {
-	BlockNumber blockNumber;
-	bool		fail = false;	/* success/failure */
-
 	/*
-	 * during initialization we don't record any updates.
+	 * update the commit log
 	 */
-	if (!RelationIsValid(LogRelation))
-		return;
-
-	/*
-	 * update the log relation
-	 */
-	TransComputeBlockNumber(LogRelation, transactionId, &blockNumber);
-	TransBlockNumberSetXidStatus(LogRelation,
-								 blockNumber,
-								 transactionId,
-								 status,
-								 &fail);
+	TransactionIdSetStatus(transactionId, status);
 
 	/*
 	 * update (invalidate) our single item TransactionLogTest cache.
@@ -191,85 +111,21 @@ TransactionLogUpdate(TransactionId transactionId,		/* trans id to update */
 	cachedTestXidStatus = status;
 }
 
-/* ----------------------------------------------------------------
- *					 transaction recovery code
- * ----------------------------------------------------------------
- */
-
 /* --------------------------------
- *		TransRecover
- *
- *		preform transaction recovery checking.
- *
- *		Note: this should only be preformed if no other backends
- *			  are running.	This is known by the postmaster and
- *			  conveyed by the postmaster passing a "do recovery checking"
- *			  flag to the backend.
- *
- *		here we get the last recorded transaction from the log,
- *		get the "last" and "next" transactions from the variable relation
- *		and then preform some integrity tests:
- *
- *		1) No transaction may exist higher then the "next" available
- *		   transaction recorded in the variable relation.  If this is the
- *		   case then it means either the log or the variable relation
- *		   has become corrupted.
- *
- *		2) The last committed transaction may not be higher then the
- *		   next available transaction for the same reason.
- *
- *		3) The last recorded transaction may not be lower then the
- *		   last committed transaction.	(the reverse is ok - it means
- *		   that some transactions have aborted since the last commit)
- *
- *		Here is what the proper situation looks like.  The line
- *		represents the data stored in the log.	'c' indicates the
- *		transaction was recorded as committed, 'a' indicates an
- *		abortted transaction and '.' represents information not
- *		recorded.  These may correspond to in progress transactions.
- *
- *			 c	c  a  c  .	.  a  .  .	.  .  .  .	.  .  .  .
- *					  |					|
- *					 last			   next
- *
- *		Since "next" is only incremented by GetNewTransactionId() which
- *		is called when transactions are started.  Hence if there
- *		are commits or aborts after "next", then it means we committed
- *		or aborted BEFORE we started the transaction.  This is the
- *		rational behind constraint (1).
- *
- *		Likewise, "last" should never greater then "next" for essentially
- *		the same reason - it would imply we committed before we started.
- *		This is the reasoning for (2).
- *
- *		(3) implies we may never have a situation such as:
+ *		AmiTransactionOverride
  *
- *			 c	c  a  c  .	.  a  c  .	.  .  .  .	.  .  .  .
- *					  |					|
- *					 last			   next
- *
- *		where there is a 'c' greater then "last".
- *
- *		Recovery checking is more difficult in the case where
- *		several backends are executing concurrently because the
- *		transactions may be executing in the other backends.
- *		So, we only do recovery stuff when the backend is explicitly
- *		passed a flag on the command line.
+ *		This function is used to manipulate the bootstrap flag.
  * --------------------------------
  */
-static void
-TransRecover(Relation logRelation)
+void
+AmiTransactionOverride(bool flag)
 {
+	AMI_OVERRIDE = flag;
 }
 
 /* ----------------------------------------------------------------
  *						Interface functions
  *
- *		InitializeTransactionLog
- *		========
- *		   this function (called near cinit) initializes
- *		   the transaction log, time and variable relations.
- *
  *		TransactionId DidCommit
  *		TransactionId DidAbort
  *		TransactionId IsInProgress
@@ -279,104 +135,13 @@ TransRecover(Relation logRelation)
  *
  *		TransactionId Commit
  *		TransactionId Abort
- *		TransactionId SetInProgress
  *		========
  *		   these functions set the transaction status
- *		   of the specified xid. TransactionIdCommit() also
- *		   records the current time in the time relation
- *		   and updates the variable relation counter.
+ *		   of the specified xid.
  *
  * ----------------------------------------------------------------
  */
 
-/*
- * InitializeTransactionLog
- *		Initializes transaction logging.
- */
-void
-InitializeTransactionLog(void)
-{
-	Relation	logRelation;
-	MemoryContext oldContext;
-
-	/*
-	 * don't do anything during bootstrapping
-	 */
-	if (AMI_OVERRIDE)
-		return;
-
-	/*
-	 * disable the transaction system so the access methods don't
-	 * interfere during initialization.
-	 */
-	OverrideTransactionSystem(true);
-
-	/*
-	 * make sure allocations occur within the top memory context so that
-	 * our log management structures are protected from garbage collection
-	 * at the end of every transaction.
-	 */
-	oldContext = MemoryContextSwitchTo(TopMemoryContext);
-
-	/*
-	 * first open the log and time relations (these are created by amiint
-	 * so they are guaranteed to exist)
-	 */
-	logRelation = heap_openr(LogRelationName, NoLock);
-
-	/*
-	 * XXX TransactionLogUpdate requires that LogRelation is valid so we
-	 * temporarily set it so we can initialize things properly. This could
-	 * be done cleaner.
-	 */
-	LogRelation = logRelation;
-
-	/*
-	 * if we have a virgin database, we initialize the log relation by
-	 * committing the BootstrapTransactionId and we initialize the
-	 * variable relation by setting the next available transaction id to
-	 * FirstNormalTransactionId.  OID initialization happens as a side
-	 * effect of bootstrapping in varsup.c.
-	 */
-	SpinAcquire(OidGenLockId);
-	if (!TransactionIdDidCommit(BootstrapTransactionId))
-	{
-		TransactionLogUpdate(BootstrapTransactionId, XID_COMMIT);
-		Assert(!IsUnderPostmaster &&
-			   TransactionIdEquals(ShmemVariableCache->nextXid,
-								   FirstNormalTransactionId));
-		ShmemVariableCache->nextXid = FirstNormalTransactionId;
-	}
-	else if (RecoveryCheckingEnabled())
-	{
-
-		/*
-		 * if we have a pre-initialized database and if the perform
-		 * recovery checking flag was passed then we do our database
-		 * integrity checking.
-		 */
-		TransRecover(logRelation);
-	}
-	LogRelation = (Relation) NULL;
-	SpinRelease(OidGenLockId);
-
-	/*
-	 * now re-enable the transaction system
-	 */
-	OverrideTransactionSystem(false);
-
-	/*
-	 * instantiate the global variables
-	 */
-	LogRelation = logRelation;
-
-	/*
-	 * restore the memory context to the previous context before we return
-	 * from initialization.
-	 */
-	MemoryContextSwitchTo(oldContext);
-}
-
 /* --------------------------------
  *		TransactionId DidCommit
  *		TransactionId DidAbort
@@ -397,16 +162,15 @@ TransactionIdDidCommit(TransactionId transactionId)
 	if (AMI_OVERRIDE)
 		return true;
 
-	return TransactionLogTest(transactionId, XID_COMMIT);
+	return TransactionLogTest(transactionId, TRANSACTION_STATUS_COMMITTED);
 }
 
 /*
- * TransactionIdDidAborted
+ * TransactionIdDidAbort
  *		True iff transaction associated with the identifier did abort.
  *
  * Note:
  *		Assumes transaction identifier is valid.
- *		XXX Is this unneeded?
  */
 bool							/* true if given transaction aborted */
 TransactionIdDidAbort(TransactionId transactionId)
@@ -414,7 +178,7 @@ TransactionIdDidAbort(TransactionId transactionId)
 	if (AMI_OVERRIDE)
 		return false;
 
-	return TransactionLogTest(transactionId, XID_ABORT);
+	return TransactionLogTest(transactionId, TRANSACTION_STATUS_ABORTED);
 }
 
 /*
@@ -422,22 +186,22 @@ TransactionIdDidAbort(TransactionId transactionId)
  * PROC structures of all running backend. - vadim 11/26/96
  *
  * Old comments:
- * true if given transaction neither committed nor aborted
-
+ * true if given transaction has neither committed nor aborted
+ */
+#ifdef NOT_USED
 bool
 TransactionIdIsInProgress(TransactionId transactionId)
 {
 	if (AMI_OVERRIDE)
 		return false;
 
-	return TransactionLogTest(transactionId, XID_INPROGRESS);
+	return TransactionLogTest(transactionId, TRANSACTION_STATUS_IN_PROGRESS);
 }
- */
+#endif /* NOT_USED */
 
 /* --------------------------------
  *		TransactionId Commit
  *		TransactionId Abort
- *		TransactionId SetInProgress
  * --------------------------------
  */
 
@@ -454,7 +218,7 @@ TransactionIdCommit(TransactionId transactionId)
 	if (AMI_OVERRIDE)
 		return;
 
-	TransactionLogUpdate(transactionId, XID_COMMIT);
+	TransactionLogUpdate(transactionId, TRANSACTION_STATUS_COMMITTED);
 }
 
 /*
@@ -470,5 +234,5 @@ TransactionIdAbort(TransactionId transactionId)
 	if (AMI_OVERRIDE)
 		return;
 
-	TransactionLogUpdate(transactionId, XID_ABORT);
+	TransactionLogUpdate(transactionId, TRANSACTION_STATUS_ABORTED);
 }
diff --git a/src/backend/access/transam/transsup.c b/src/backend/access/transam/transsup.c
deleted file mode 100644
index 3fd6c9d3987..00000000000
--- a/src/backend/access/transam/transsup.c
+++ /dev/null
@@ -1,466 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * transsup.c
- *	  postgres transaction access method support code
- *
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- *
- * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/Attic/transsup.c,v 1.31 2001/07/12 04:11:13 tgl Exp $
- *
- * NOTES
- *	  This file contains support functions for the high
- *	  level access method interface routines found in transam.c
- *
- *-------------------------------------------------------------------------
- */
-#include "postgres.h"
-
-#include "access/xact.h"
-#include "utils/bit.h"
-
-
-/* ----------------
- *		transaction system version id
- *
- *		this is stored on the first page of the log, time and variable
- *		relations on the first 4 bytes.  This is so that if we improve
- *		the format of the transaction log after postgres version 2, then
- *		people won't have to rebuild their databases.
- *
- *		TRANS_SYSTEM_VERSION 100 means major version 1 minor version 0.
- *		Two databases with the same major version should be compatible,
- *		even if their minor versions differ.
- *
- *		XXX This isn't actually being used!
- * ----------------
- */
-#define TRANS_SYSTEM_VERSION	200
-
-/* ----------------
- *		LogRelationContents structure
- *
- *		This structure describes the storage of the data in the
- *		first 128 bytes of the log relation.  This storage is never
- *		used for transaction status because transaction id's begin
- *		their numbering at 512.
- *
- *		The first 4 bytes of this relation store the version
- *		number of the transaction system.
- *
- *		XXX This isn't actually being used!
- * ----------------
- */
-typedef struct LogRelationContentsData
-{
-	XLogRecPtr	LSN;			/* temp hack: LSN is member of any block */
-	/* so should be described in bufmgr */
-	int			TransSystemVersion;
-} LogRelationContentsData;
-
-typedef LogRelationContentsData *LogRelationContents;
-
-
-/* ----------------
- *		BitIndexOf computes the index of the Nth xid on a given block
- * ----------------
- */
-#define BitIndexOf(N)	((N) * 2)
-
-/* ----------------
- *		transaction page definitions
- * ----------------
- */
-#define TP_DataSize				(BLCKSZ - sizeof(XLogRecPtr))
-#define TP_NumXidStatusPerBlock (TP_DataSize * 4)
-
-
-static XidStatus TransBlockGetXidStatus(Block tblock,
-					   TransactionId transactionId);
-static void TransBlockSetXidStatus(Block tblock,
-					   TransactionId transactionId, XidStatus xstatus);
-
-/* ----------------------------------------------------------------
- *					  general support routines
- * ----------------------------------------------------------------
- */
-
-/* --------------------------------
- *		AmiTransactionOverride
- *
- *		This function is used to manipulate the bootstrap flag.
- * --------------------------------
- */
-void
-AmiTransactionOverride(bool flag)
-{
-	AMI_OVERRIDE = flag;
-}
-
-/* --------------------------------
- *		TransComputeBlockNumber
- * --------------------------------
- */
-void
-TransComputeBlockNumber(Relation relation,		/* relation to test */
-						TransactionId transactionId,	/* transaction id to
-														 * test */
-						BlockNumber *blockNumberOutP)
-{
-	uint32		itemsPerBlock = 0;
-
-	/*
-	 * we calculate the block number of our transaction by dividing the
-	 * transaction id by the number of transaction things per block.
-	 */
-	if (relation == LogRelation)
-		itemsPerBlock = TP_NumXidStatusPerBlock;
-	else
-		elog(ERROR, "TransComputeBlockNumber: unknown relation");
-
-	/* ----------------
-	 *	warning! if the transaction id's get too large
-	 *	then a BlockNumber may not be large enough to hold the results
-	 *	of our division.
-	 *
-	 *	XXX  this will all vanish soon when we implement an improved
-	 *		 transaction id schema -cim 3/23/90
-	 *
-	 *	This has vanished now that xid's are 4 bytes (no longer 5).
-	 *	-mer 5/24/92
-	 * ----------------
-	 */
-	(*blockNumberOutP) = transactionId / itemsPerBlock;
-}
-
-
-/* ----------------------------------------------------------------
- *					 trans block support routines
- * ----------------------------------------------------------------
- */
-
-/* --------------------------------
- *		TransBlockGetLastTransactionIdStatus
- *
- *		This returns the status and transaction id of the last
- *		transaction information recorded on the given TransBlock.
- * --------------------------------
- */
-
-#ifdef NOT_USED
-static XidStatus
-TransBlockGetLastTransactionIdStatus(Block tblock,
-									 TransactionId baseXid,
-									 TransactionId *returnXidP)
-{
-	Index		index;
-	Index		maxIndex;
-	bits8		bit1;
-	bits8		bit2;
-	BitIndex	offset;
-	XidStatus	xstatus;
-
-	/*
-	 * sanity check
-	 */
-	Assert((tblock != NULL));
-
-	/*
-	 * search downward from the top of the block data, looking for the
-	 * first Non-in progress transaction status.  Since we are scanning
-	 * backward, this will be last recorded transaction status on the
-	 * block.
-	 */
-	maxIndex = TP_NumXidStatusPerBlock;
-	for (index = maxIndex; index > 0; index--)
-	{
-		offset = BitIndexOf(index - 1);
-		bit1 = ((bits8) BitArrayBitIsSet((BitArray) tblock, offset++)) << 1;
-		bit2 = (bits8) BitArrayBitIsSet((BitArray) tblock, offset);
-
-		xstatus = (bit1 | bit2);
-
-		/*
-		 * here we have the status of some transaction, so test if the
-		 * status is recorded as "in progress".  If so, then we save the
-		 * transaction id in the place specified by the caller.
-		 */
-		if (xstatus != XID_INPROGRESS)
-		{
-			if (returnXidP != NULL)
-				TransactionIdStore(baseXid + (index - 1), returnXidP);
-			break;
-		}
-	}
-
-	/*
-	 * if we get here and index is 0 it means we couldn't find a
-	 * non-inprogress transaction on the block.  For now we just return
-	 * this info to the user.  They can check if the return status is "in
-	 * progress" to know this condition has arisen.
-	 */
-	if (index == 0)
-	{
-		if (returnXidP != NULL)
-			TransactionIdStore(baseXid, returnXidP);
-	}
-
-	/*
-	 * return the status to the user
-	 */
-	return xstatus;
-}
-
-#endif
-
-/* --------------------------------
- *		TransBlockGetXidStatus
- *
- *		This returns the status of the desired transaction
- * --------------------------------
- */
-
-static XidStatus
-TransBlockGetXidStatus(Block tblock,
-					   TransactionId transactionId)
-{
-	Index		index;
-	bits8		bit1;
-	bits8		bit2;
-	BitIndex	offset;
-
-	tblock = (Block) ((char *) tblock + sizeof(XLogRecPtr));
-
-	/* ----------------
-	 *	calculate the index into the transaction data where
-	 *	our transaction status is located
-	 *
-	 *	XXX this will be replaced soon when we move to the
-	 *		new transaction id scheme -cim 3/23/90
-	 *
-	 *	The old system has now been replaced. -mer 5/24/92
-	 * ----------------
-	 */
-	index = transactionId % TP_NumXidStatusPerBlock;
-
-	/*
-	 * get the data at the specified index
-	 */
-	offset = BitIndexOf(index);
-	bit1 = ((bits8) BitArrayBitIsSet((BitArray) tblock, offset++)) << 1;
-	bit2 = (bits8) BitArrayBitIsSet((BitArray) tblock, offset);
-
-	/*
-	 * return the transaction status to the caller
-	 */
-	return (XidStatus) (bit1 | bit2);
-}
-
-/* --------------------------------
- *		TransBlockSetXidStatus
- *
- *		This sets the status of the desired transaction
- * --------------------------------
- */
-static void
-TransBlockSetXidStatus(Block tblock,
-					   TransactionId transactionId,
-					   XidStatus xstatus)
-{
-	Index		index;
-	BitIndex	offset;
-
-	tblock = (Block) ((char *) tblock + sizeof(XLogRecPtr));
-
-	/* ----------------
-	 *	calculate the index into the transaction data where
-	 *	we sould store our transaction status.
-	 *
-	 *	XXX this will be replaced soon when we move to the
-	 *		new transaction id scheme -cim 3/23/90
-	 *
-	 *	The new scheme is here -mer 5/24/92
-	 * ----------------
-	 */
-	index = transactionId % TP_NumXidStatusPerBlock;
-
-	offset = BitIndexOf(index);
-
-	/*
-	 * store the transaction value at the specified offset
-	 */
-	switch (xstatus)
-	{
-		case XID_COMMIT:		/* set 10 */
-			BitArraySetBit((BitArray) tblock, offset);
-			BitArrayClearBit((BitArray) tblock, offset + 1);
-			break;
-		case XID_ABORT: /* set 01 */
-			BitArrayClearBit((BitArray) tblock, offset);
-			BitArraySetBit((BitArray) tblock, offset + 1);
-			break;
-		case XID_INPROGRESS:	/* set 00 */
-			BitArrayClearBit((BitArray) tblock, offset);
-			BitArrayClearBit((BitArray) tblock, offset + 1);
-			break;
-		default:
-			elog(NOTICE,
-				 "TransBlockSetXidStatus: invalid status: %d (ignored)",
-				 xstatus);
-			break;
-	}
-}
-
-/* ----------------------------------------------------------------
- *				   transam i/o support routines
- * ----------------------------------------------------------------
- */
-
-/* --------------------------------
- *		TransBlockNumberGetXidStatus
- * --------------------------------
- */
-XidStatus
-TransBlockNumberGetXidStatus(Relation relation,
-							 BlockNumber blockNumber,
-							 TransactionId xid,
-							 bool *failP)
-{
-	Buffer		buffer;			/* buffer associated with block */
-	Block		block;			/* block containing xstatus */
-	XidStatus	xstatus;		/* recorded status of xid */
-	bool		localfail;		/* bool used if failP = NULL */
-
-	/*
-	 * get the page containing the transaction information
-	 */
-	buffer = ReadBuffer(relation, blockNumber);
-	LockBuffer(buffer, BUFFER_LOCK_SHARE);
-	block = BufferGetBlock(buffer);
-
-	/*
-	 * get the status from the block.  note, for now we always return
-	 * false in failP.
-	 */
-	if (failP == NULL)
-		failP = &localfail;
-	(*failP) = false;
-
-	xstatus = TransBlockGetXidStatus(block, xid);
-
-	/*
-	 * release the buffer and return the status
-	 */
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	ReleaseBuffer(buffer);
-
-	return xstatus;
-}
-
-/* --------------------------------
- *		TransBlockNumberSetXidStatus
- * --------------------------------
- */
-void
-TransBlockNumberSetXidStatus(Relation relation,
-							 BlockNumber blockNumber,
-							 TransactionId xid,
-							 XidStatus xstatus,
-							 bool *failP)
-{
-	Buffer		buffer;			/* buffer associated with block */
-	Block		block;			/* block containing xstatus */
-	bool		localfail;		/* bool used if failP = NULL */
-
-	/*
-	 * get the block containing the transaction status
-	 */
-	buffer = ReadBuffer(relation, blockNumber);
-	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
-	block = BufferGetBlock(buffer);
-
-	/*
-	 * attempt to update the status of the transaction on the block. if we
-	 * are successful, write the block. otherwise release the buffer.
-	 * note, for now we always return false in failP.
-	 */
-	if (failP == NULL)
-		failP = &localfail;
-	(*failP) = false;
-
-	TransBlockSetXidStatus(block, xid, xstatus);
-
-	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
-	if ((*failP) == false)
-		WriteBuffer(buffer);
-	else
-		ReleaseBuffer(buffer);
-}
-
-/* --------------------------------
- *		TransGetLastRecordedTransaction
- * --------------------------------
- */
-#ifdef NOT_USED
-void
-TransGetLastRecordedTransaction(Relation relation,
-								TransactionId xid,		/* return: transaction
-														 * id */
-								bool *failP)
-{
-	BlockNumber blockNumber;	/* block number */
-	Buffer		buffer;			/* buffer associated with block */
-	Block		block;			/* block containing xid status */
-	BlockNumber n;				/* number of blocks in the relation */
-	TransactionId baseXid;
-
-	(*failP) = false;
-
-	/*
-	 * SOMEDAY gain exclusive access to the log relation
-	 *
-	 * That someday is today 5 Aug. 1991 -mer It looks to me like we only
-	 * need to set a read lock here, despite the above comment about
-	 * exclusive access.  The block is never actually written into, we
-	 * only check status bits.
-	 */
-	RelationSetLockForRead(relation);
-
-	/*
-	 * we assume the last block of the log contains the last recorded
-	 * transaction.  If the relation is empty we return failure to the
-	 * user.
-	 */
-	n = RelationGetNumberOfBlocks(relation);
-	if (n == 0)
-	{
-		(*failP) = true;
-		return;
-	}
-
-	/*
-	 * get the block containing the transaction information
-	 */
-	blockNumber = n - 1;
-	buffer = ReadBuffer(relation, blockNumber);
-	block = BufferGetBlock(buffer);
-
-	/*
-	 * get the last xid on the block
-	 */
-	baseXid = blockNumber * TP_NumXidStatusPerBlock;
-
-/* XXX ???? xid won't get returned! - AY '94 */
-	TransBlockGetLastTransactionIdStatus(block, baseXid, &xid);
-
-	ReleaseBuffer(buffer);
-
-	/*
-	 * SOMEDAY release our lock on the log relation
-	 */
-	RelationUnsetLockForRead(relation);
-}
-
-#endif
diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 86d38c148fa..6b25e0a8011 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -6,15 +6,15 @@
  * Copyright (c) 2000, PostgreSQL Global Development Group
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.44 2001/08/23 23:06:37 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.45 2001/08/25 18:52:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 
 #include "postgres.h"
 
+#include "access/clog.h"
 #include "access/transam.h"
-#include "access/xlog.h"
 #include "storage/proc.h"
 
 
@@ -32,26 +32,35 @@ VariableCache ShmemVariableCache = NULL;
 /*
  * Allocate the next XID for my new transaction.
  */
-void
-GetNewTransactionId(TransactionId *xid)
+TransactionId
+GetNewTransactionId(void)
 {
+	TransactionId	xid;
+
 	/*
 	 * During bootstrap initialization, we return the special bootstrap
 	 * transaction id.
 	 */
 	if (AMI_OVERRIDE)
-	{
-		*xid = BootstrapTransactionId;
-		return;
-	}
+		return BootstrapTransactionId;
 
 	SpinAcquire(XidGenLockId);
 
-	*xid = ShmemVariableCache->nextXid;
+	xid = ShmemVariableCache->nextXid;
 
 	TransactionIdAdvance(ShmemVariableCache->nextXid);
 
 	/*
+	 * If we have just allocated the first XID of a new page of the
+	 * commit log, zero out that commit-log page before returning.
+	 * We must do this while holding XidGenLock, else another xact could
+	 * acquire and commit a later XID before we zero the page.  Fortunately,
+	 * a page of the commit log holds 32K or more transactions, so we don't
+	 * have to do this very often.
+	 */
+	ExtendCLOG(xid);
+
+	/*
 	 * Must set MyProc->xid before releasing XidGenLock.  This ensures that
 	 * when GetSnapshotData calls ReadNewTransactionId, all active XIDs
 	 * before the returned value of nextXid are already present in the shared
@@ -72,30 +81,33 @@ GetNewTransactionId(TransactionId *xid)
 	 * removed while holding the lock.)
 	 */
 	if (MyProc != (PROC *) NULL)
-		MyProc->xid = *xid;
+		MyProc->xid = xid;
 
 	SpinRelease(XidGenLockId);
+
+	return xid;
 }
 
 /*
  * Read nextXid but don't allocate it.
  */
-void
-ReadNewTransactionId(TransactionId *xid)
+TransactionId
+ReadNewTransactionId(void)
 {
+	TransactionId	xid;
+
 	/*
 	 * During bootstrap initialization, we return the special bootstrap
 	 * transaction id.
 	 */
 	if (AMI_OVERRIDE)
-	{
-		*xid = BootstrapTransactionId;
-		return;
-	}
+		return BootstrapTransactionId;
 
 	SpinAcquire(XidGenLockId);
-	*xid = ShmemVariableCache->nextXid;
+	xid = ShmemVariableCache->nextXid;
 	SpinRelease(XidGenLockId);
+
+	return xid;
 }
 
 /* ----------------------------------------------------------------
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index f35e8d9203e..c3d6326d42a 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.108 2001/07/16 22:43:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.109 2001/08/25 18:52:41 tgl Exp $
  *
  * NOTES
  *		Transaction aborts can now occur two ways:
@@ -229,22 +229,6 @@ static void (*_RollbackFunc) (void *) = NULL;
 static void *_RollbackData = NULL;
 
 /* ----------------
- *		info returned when the system is disabled
- *
- * Apparently a lot of this code is inherited from other prototype systems.
- *
- * For DisabledStartTime, use a symbolic value to make the relationships clearer.
- * The old value of 1073741823 corresponds to a date in y2004, which is coming closer
- *	every day. It appears that if we return a value guaranteed larger than
- *	any real time associated with a transaction then comparisons in other
- *	modules will still be correct. Let's use BIG_ABSTIME for this. tgl 2/14/97
- * ----------------
- */
-static CommandId	DisabledCommandId = (CommandId) -1;
-
-static AbsoluteTime DisabledStartTime = (AbsoluteTime) BIG_ABSTIME;
-
-/* ----------------
  *		catalog creation transaction bootstrapping flag.
  *		This should be eliminated and added to the transaction
  *		state stuff.  -cim 3/19/90
@@ -309,8 +293,6 @@ IsTransactionState(void)
 			return true;
 		case TRANS_ABORT:
 			return true;
-		case TRANS_DISABLED:
-			return false;
 	}
 
 	/*
@@ -339,44 +321,9 @@ IsAbortedTransactionBlockState(void)
 	return false;
 }
 
-/* --------------------------------
- *		OverrideTransactionSystem
- *
- *		This is used to temporarily disable the transaction
- *		processing system in order to do initialization of
- *		the transaction system data structures and relations
- *		themselves.
- * --------------------------------
- */
-static int		SavedTransactionState;
-
-void
-OverrideTransactionSystem(bool flag)
-{
-	TransactionState s = CurrentTransactionState;
-
-	if (flag == true)
-	{
-		if (s->state == TRANS_DISABLED)
-			return;
-
-		SavedTransactionState = s->state;
-		s->state = TRANS_DISABLED;
-	}
-	else
-	{
-		if (s->state != TRANS_DISABLED)
-			return;
-
-		s->state = SavedTransactionState;
-	}
-}
 
 /* --------------------------------
  *		GetCurrentTransactionId
- *
- *		This returns the id of the current transaction, or
- *		the id of the "disabled" transaction.
  * --------------------------------
  */
 TransactionId
@@ -384,16 +331,6 @@ GetCurrentTransactionId(void)
 {
 	TransactionState s = CurrentTransactionState;
 
-	/*
-	 * if the transaction system is disabled, we return the special
-	 * "disabled" transaction id.
-	 */
-	if (s->state == TRANS_DISABLED)
-		return DisabledTransactionId;
-
-	/*
-	 * otherwise return the current transaction id.
-	 */
 	return s->transactionIdData;
 }
 
@@ -407,13 +344,6 @@ GetCurrentCommandId(void)
 {
 	TransactionState s = CurrentTransactionState;
 
-	/*
-	 * if the transaction system is disabled, we return the special
-	 * "disabled" command id.
-	 */
-	if (s->state == TRANS_DISABLED)
-		return DisabledCommandId;
-
 	return s->commandId;
 }
 
@@ -422,13 +352,6 @@ GetScanCommandId(void)
 {
 	TransactionState s = CurrentTransactionState;
 
-	/*
-	 * if the transaction system is disabled, we return the special
-	 * "disabled" command id.
-	 */
-	if (s->state == TRANS_DISABLED)
-		return DisabledCommandId;
-
 	return s->scanCommandId;
 }
 
@@ -442,13 +365,6 @@ GetCurrentTransactionStartTime(void)
 {
 	TransactionState s = CurrentTransactionState;
 
-	/*
-	 * if the transaction system is disabled, we return the special
-	 * "disabled" starting time.
-	 */
-	if (s->state == TRANS_DISABLED)
-		return DisabledStartTime;
-
 	return s->startTime;
 }
 
@@ -524,16 +440,6 @@ SetScanCommandId(CommandId savedId)
 }
 
 /* ----------------------------------------------------------------
- *						initialization stuff
- * ----------------------------------------------------------------
- */
-void
-InitializeTransactionSystem(void)
-{
-	InitializeTransactionLog();
-}
-
-/* ----------------------------------------------------------------
  *						StartTransaction stuff
  * ----------------------------------------------------------------
  */
@@ -617,15 +523,19 @@ AtStart_Memory(void)
  * --------------------------------
  */
 void
-RecordTransactionCommit()
+RecordTransactionCommit(void)
 {
 	TransactionId xid;
 	bool		leak;
 
-	xid = GetCurrentTransactionId();
-
 	leak = BufferPoolCheckLeak();
 
+	xid = GetCurrentTransactionId();
+
+	/*
+	 * We needn't write anything in xlog or clog if the transaction was
+	 * read-only, which we check by testing if it made any xlog entries.
+	 */
 	if (MyLastRecPtr.xrecoff != 0)
 	{
 		XLogRecData rdata;
@@ -673,6 +583,7 @@ RecordTransactionCommit()
 		/* Break the chain of back-links in the XLOG records I output */
 		MyLastRecPtr.xrecoff = 0;
 
+		/* Mark the transaction committed in clog */
 		TransactionIdCommit(xid);
 
 		END_CRIT_SECTION();
@@ -765,7 +676,10 @@ RecordTransactionAbort(void)
 	TransactionId xid = GetCurrentTransactionId();
 
 	/*
-	 * Double check here is to catch case that we aborted partway through
+	 * We needn't write anything in xlog or clog if the transaction was
+	 * read-only, which we check by testing if it made any xlog entries.
+	 *
+	 * Extra check here is to catch case that we aborted partway through
 	 * RecordTransactionCommit ...
 	 */
 	if (MyLastRecPtr.xrecoff != 0 && !TransactionIdDidCommit(xid))
@@ -782,8 +696,17 @@ RecordTransactionAbort(void)
 
 		START_CRIT_SECTION();
 
+		/*
+		 * SHOULD SAVE ARRAY OF RELFILENODE-s TO DROP
+		 */
 		recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, &rdata);
 
+		/*
+		 * There's no need for XLogFlush here, since the default assumption
+		 * would be that we aborted, anyway.
+		 */
+
+		/* Mark the transaction aborted in clog */
 		TransactionIdAbort(xid);
 
 		END_CRIT_SECTION();
@@ -913,7 +836,7 @@ StartTransaction(void)
 	 * fix to a communications problem, and we keep having to deal with it
 	 * here.  We should fix the comm channel code.	mao 080891
 	 */
-	if (s->state == TRANS_DISABLED || s->state == TRANS_INPROGRESS)
+	if (s->state == TRANS_INPROGRESS)
 		return;
 
 	/*
@@ -927,7 +850,7 @@ StartTransaction(void)
 	/*
 	 * generate a new transaction id
 	 */
-	GetNewTransactionId(&(s->transactionIdData));
+	s->transactionIdData = GetNewTransactionId();
 
 	XactLockTableInsert(s->transactionIdData);
 
@@ -984,11 +907,8 @@ CommitTransaction(void)
 	/*
 	 * check the current transaction state
 	 */
-	if (s->state == TRANS_DISABLED)
-		return;
-
 	if (s->state != TRANS_INPROGRESS)
-		elog(NOTICE, "CommitTransaction and not in in-progress state ");
+		elog(NOTICE, "CommitTransaction and not in in-progress state");
 
 	/*
 	 * Tell the trigger manager that this transaction is about to be
@@ -1109,12 +1029,6 @@ AbortTransaction(void)
 	/*
 	 * check the current transaction state
 	 */
-	if (s->state == TRANS_DISABLED)
-	{
-		RESUME_INTERRUPTS();
-		return;
-	}
-
 	if (s->state != TRANS_INPROGRESS)
 		elog(NOTICE, "AbortTransaction and not in in-progress state");
 
@@ -1138,7 +1052,7 @@ AbortTransaction(void)
 	CloseSequences();
 	AtEOXact_portals();
 
-	/* Advertise the fact that we aborted in pg_log. */
+	/* Advertise the fact that we aborted in pg_clog. */
 	RecordTransactionAbort();
 
 	/*
@@ -1191,9 +1105,6 @@ CleanupTransaction(void)
 {
 	TransactionState s = CurrentTransactionState;
 
-	if (s->state == TRANS_DISABLED)
-		return;
-
 	/*
 	 * State should still be TRANS_ABORT from AbortTransaction().
 	 */
@@ -1464,9 +1375,6 @@ BeginTransactionBlock(void)
 	/*
 	 * check the current transaction state
 	 */
-	if (s->state == TRANS_DISABLED)
-		return;
-
 	if (s->blockState != TBLOCK_DEFAULT)
 		elog(NOTICE, "BEGIN: already a transaction in progress");
 
@@ -1498,9 +1406,6 @@ EndTransactionBlock(void)
 	/*
 	 * check the current transaction state
 	 */
-	if (s->state == TRANS_DISABLED)
-		return;
-
 	if (s->blockState == TBLOCK_INPROGRESS)
 	{
 
@@ -1552,9 +1457,6 @@ AbortTransactionBlock(void)
 	/*
 	 * check the current transaction state
 	 */
-	if (s->state == TRANS_DISABLED)
-		return;
-
 	if (s->blockState == TBLOCK_INPROGRESS)
 	{
 
@@ -1592,12 +1494,6 @@ UserAbortTransactionBlock(void)
 	TransactionState s = CurrentTransactionState;
 
 	/*
-	 * check the current transaction state
-	 */
-	if (s->state == TRANS_DISABLED)
-		return;
-
-	/*
 	 * if the transaction has already been automatically aborted with an
 	 * error, and the user subsequently types 'abort', allow it.  (the
 	 * behavior is the same as if they had typed 'end'.)
@@ -1665,7 +1561,6 @@ AbortOutOfAnyTransaction(void)
 			CleanupTransaction();
 			break;
 		case TRANS_DEFAULT:
-		case TRANS_DISABLED:
 			/* Not in a transaction, do nothing */
 			break;
 	}
@@ -1700,7 +1595,10 @@ xact_redo(XLogRecPtr lsn, XLogRecord *record)
 		/* SHOULD REMOVE FILES OF ALL DROPPED RELATIONS */
 	}
 	else if (info == XLOG_XACT_ABORT)
+	{
 		TransactionIdAbort(record->xl_xid);
+		/* SHOULD REMOVE FILES OF ALL FAILED-TO-BE-CREATED RELATIONS */
+	}
 	else
 		elog(STOP, "xact_redo: unknown op code %u", info);
 }
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 9389f159969..567937ebaee 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.74 2001/08/23 23:06:37 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.75 2001/08/25 18:52:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -26,8 +26,11 @@
 #include <locale.h>
 #endif
 
+#include "access/clog.h"
 #include "access/transam.h"
 #include "access/xact.h"
+#include "access/xlog.h"
+#include "access/xlogutils.h"
 #include "catalog/catversion.h"
 #include "catalog/pg_control.h"
 #include "storage/sinval.h"
@@ -35,8 +38,6 @@
 #include "storage/spin.h"
 #include "storage/s_lock.h"
 #include "storage/bufpage.h"
-#include "access/xlog.h"
-#include "access/xlogutils.h"
 #include "utils/builtins.h"
 #include "utils/relcache.h"
 #include "utils/selfuncs.h"
@@ -1580,7 +1581,7 @@ MoveOfflineLogs(uint32 log, uint32 seg, XLogRecPtr endptr)
 			strspn(xlde->d_name, "0123456789ABCDEF") == 16 &&
 			strcmp(xlde->d_name, lastoff) <= 0)
 		{
-			sprintf(path, "%s/%s", XLogDir, xlde->d_name);
+			snprintf(path, MAXPGPATH, "%s/%s", XLogDir, xlde->d_name);
 			if (XLOG_archive_dir[0])
 			{
 				elog(LOG, "archiving transaction log file %s",
@@ -2409,6 +2410,9 @@ BootStrapXLOG(void)
 	/* some additional ControlFile fields are set in WriteControlFile() */
 
 	WriteControlFile();
+
+	/* Bootstrap the commit log, too */
+	BootStrapCLOG();
 }
 
 static char *
@@ -2543,7 +2547,6 @@ StartupXLOG(void)
 		ControlFile->time = time(NULL);
 		UpdateControlFile();
 
-		XLogOpenLogRelation();	/* open pg_log */
 		XLogInitRelationCache();
 
 		/* Is REDO required ? */
@@ -2724,6 +2727,9 @@ StartupXLOG(void)
 	ThisStartUpID++;
 	XLogCtl->ThisStartUpID = ThisStartUpID;
 
+	/* Start up the commit log, too */
+	StartupCLOG();
+
 	elog(LOG, "database system is ready");
 	CritSectionCount--;
 
@@ -2845,6 +2851,7 @@ ShutdownXLOG(void)
 	CritSectionCount++;
 	CreateDummyCaches();
 	CreateCheckPoint(true);
+	ShutdownCLOG();
 	CritSectionCount--;
 
 	elog(LOG, "database system is shut down");
@@ -2981,6 +2988,9 @@ CreateCheckPoint(bool shutdown)
 	 */
 	FlushBufferPool();
 
+	/* And commit-log buffers, too */
+	CheckPointCLOG();
+
 	/*
 	 * Now insert the checkpoint record into XLOG.
 	 */
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index 9e9aa794660..4cae914cf41 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -6,24 +6,21 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Header: /cvsroot/pgsql/src/backend/access/transam/xlogutils.c,v 1.17 2001/08/23 23:06:37 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/xlogutils.c,v 1.18 2001/08/25 18:52:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #include "postgres.h"
 
-#include "access/xlog.h"
-#include "access/transam.h"
-#include "access/xact.h"
-#include "storage/bufpage.h"
-#include "storage/bufmgr.h"
-#include "storage/smgr.h"
 #include "access/htup.h"
 #include "access/xlogutils.h"
 #include "catalog/pg_database.h"
 #include "lib/hasht.h"
+#include "storage/bufpage.h"
+#include "storage/smgr.h"
 #include "utils/relcache.h"
 
+
 /*
  * ---------------------------------------------------------------
  *
@@ -153,33 +150,6 @@ XLogIsValidTuple(RelFileNode hnode, ItemPointer iptr)
 }
 
 /*
- * Open pg_log in recovery
- */
-extern Relation LogRelation;	/* pg_log relation */
-
-void
-XLogOpenLogRelation(void)
-{
-	Relation	logRelation;
-
-	Assert(!LogRelation);
-	logRelation = (Relation) malloc(sizeof(RelationData));
-	memset(logRelation, 0, sizeof(RelationData));
-	logRelation->rd_rel = (Form_pg_class) malloc(sizeof(FormData_pg_class));
-	memset(logRelation->rd_rel, 0, sizeof(FormData_pg_class));
-
-	sprintf(RelationGetPhysicalRelationName(logRelation), "pg_log");
-	logRelation->rd_node.tblNode = InvalidOid;
-	logRelation->rd_node.relNode = RelOid_pg_log;
-	logRelation->rd_targblock = InvalidBlockNumber;
-	logRelation->rd_fd = -1;
-	logRelation->rd_fd = smgropen(DEFAULT_SMGR, logRelation, false);
-	if (logRelation->rd_fd < 0)
-		elog(STOP, "XLogOpenLogRelation: failed to open pg_log");
-	LogRelation = logRelation;
-}
-
-/*
  * ---------------------------------------------------------------
  *
  * Storage related support functions
diff --git a/src/backend/catalog/Makefile b/src/backend/catalog/Makefile
index 999897d9fee..6c5d2aaec2c 100644
--- a/src/backend/catalog/Makefile
+++ b/src/backend/catalog/Makefile
@@ -2,7 +2,7 @@
 #
 # Makefile for catalog
 #
-# $Header: /cvsroot/pgsql/src/backend/catalog/Makefile,v 1.36 2001/08/24 14:07:48 petere Exp $
+# $Header: /cvsroot/pgsql/src/backend/catalog/Makefile,v 1.37 2001/08/25 18:52:41 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -31,7 +31,7 @@ POSTGRES_BKI_SRCS := $(addprefix $(top_srcdir)/src/include/catalog/,\
 	pg_operator.h pg_opclass.h pg_am.h pg_amop.h pg_amproc.h \
 	pg_language.h pg_largeobject.h pg_aggregate.h pg_statistic.h \
 	pg_rewrite.h pg_trigger.h pg_listener.h pg_description.h \
-	pg_database.h pg_shadow.h pg_group.h pg_log.h indexing.h \
+	pg_database.h pg_shadow.h pg_group.h indexing.h \
     )
 
 pg_includes := $(sort -I$(top_srcdir)/src/include -I$(top_builddir)/src/include)
diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index 4db48b90723..4f7b04a36a0 100644
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.174 2001/08/10 18:57:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.175 2001/08/25 18:52:41 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -252,11 +252,6 @@ heap_create(char *relname,
 			tblNode = InvalidOid;
 			relid = RelOid_pg_database;
 		}
-		else if (strcmp(LogRelationName, relname) == 0)
-		{
-			tblNode = InvalidOid;
-			relid = RelOid_pg_log;
-		}
 		else
 		{
 			relid = newoid();
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ada73b1e7ca..84ef63e6295 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.247 2001/08/21 16:36:03 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.248 2001/08/25 18:52:41 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -51,7 +51,6 @@
 #include <ctype.h>
 
 #include "access/htup.h"
-#include "catalog/catname.h"
 #include "catalog/pg_type.h"
 #include "nodes/params.h"
 #include "nodes/parsenodes.h"
@@ -5423,11 +5422,7 @@ relation_name:	SpecialRuleRelation
 				}
 		| ColId
 				{
-					/* disallow refs to variable system tables */
-					if (strcmp(LogRelationName, $1) == 0)
-						elog(ERROR,"%s cannot be accessed by users",$1);
-					else
-						$$ = $1;
+					$$ = $1;
 				}
 		;
 
diff --git a/src/backend/storage/buffer/README b/src/backend/storage/buffer/README
index 519c9c9ebc0..498deb489d3 100644
--- a/src/backend/storage/buffer/README
+++ b/src/backend/storage/buffer/README
@@ -1,4 +1,4 @@
-$Header: /cvsroot/pgsql/src/backend/storage/buffer/README,v 1.1 2001/07/06 21:04:25 tgl Exp $
+$Header: /cvsroot/pgsql/src/backend/storage/buffer/README,v 1.2 2001/08/25 18:52:42 tgl Exp $
 
 Notes about shared buffer access rules
 --------------------------------------
@@ -66,7 +66,7 @@ at about the same time would OR the same bits into the field, so there
 is little or no risk of conflicting update; what's more, if there did
 manage to be a conflict it would merely mean that one bit-update would
 be lost and need to be done again later.  These four bits are only hints
-(they cache the results of transaction status lookups in pg_log), so no
+(they cache the results of transaction status lookups in pg_clog), so no
 great harm is done if they get reset to zero by conflicting updates.
 
 5. To physically remove a tuple or compact free space on a page, one
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 75736c8f240..06988baf345 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.41 2001/06/27 23:31:39 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipci.c,v 1.42 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,6 +17,7 @@
 #include <sys/types.h>
 
 #include "miscadmin.h"
+#include "access/clog.h"
 #include "access/xlog.h"
 #include "storage/bufmgr.h"
 #include "storage/freespace.h"
@@ -51,6 +52,7 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int maxBackends)
 	size = BufferShmemSize();
 	size += LockShmemSize(maxBackends);
 	size += XLOGShmemSize();
+	size += CLOGShmemSize();
 	size += SLockShmemSize();
 	size += SInvalShmemSize(maxBackends);
 	size += FreeSpaceShmemSize();
@@ -80,9 +82,10 @@ CreateSharedMemoryAndSemaphores(bool makePrivate, int maxBackends)
 	InitShmemAllocation(seghdr);
 
 	/*
-	 * Set up xlog and buffers
+	 * Set up xlog, clog, and buffers
 	 */
 	XLOGShmemInit();
+	CLOGShmemInit();
 	InitBufferPool();
 
 	/*
diff --git a/src/backend/storage/ipc/sinval.c b/src/backend/storage/ipc/sinval.c
index de05c4a84a2..985577c4a6c 100644
--- a/src/backend/storage/ipc/sinval.c
+++ b/src/backend/storage/ipc/sinval.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.38 2001/08/23 23:06:37 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.39 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -327,7 +327,7 @@ GetSnapshotData(bool serializable)
 	 *--------------------
 	 */
 
-	ReadNewTransactionId(&(snapshot->xmax));
+	snapshot->xmax = ReadNewTransactionId();
 
 	for (index = 0; index < segP->lastBackend; index++)
 	{
diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index 10861348e80..6105a3248ce 100644
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.49 2001/07/09 22:18:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lmgr.c,v 1.50 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -373,7 +373,7 @@ XactLockTableWait(TransactionId xid)
 
 	/*
 	 * Transaction was committed/aborted/crashed - we have to update
-	 * pg_log if transaction is still marked as running.
+	 * pg_clog if transaction is still marked as running.
 	 */
 	if (!TransactionIdDidCommit(xid) && !TransactionIdDidAbort(xid))
 		TransactionIdAbort(xid);
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 481db43c7de..c626cd6de8c 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.142 2001/08/10 18:57:37 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/cache/relcache.c,v 1.143 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,7 +43,6 @@
 #include "catalog/indexing.h"
 #include "catalog/pg_attrdef.h"
 #include "catalog/pg_index.h"
-#include "catalog/pg_log.h"
 #include "catalog/pg_proc.h"
 #include "catalog/pg_relcheck.h"
 #include "catalog/pg_rewrite.h"
@@ -67,7 +66,6 @@ static FormData_pg_attribute Desc_pg_class[Natts_pg_class] = {Schema_pg_class};
 static FormData_pg_attribute Desc_pg_attribute[Natts_pg_attribute] = {Schema_pg_attribute};
 static FormData_pg_attribute Desc_pg_proc[Natts_pg_proc] = {Schema_pg_proc};
 static FormData_pg_attribute Desc_pg_type[Natts_pg_type] = {Schema_pg_type};
-static FormData_pg_attribute Desc_pg_log[Natts_pg_log] = {Schema_pg_log};
 
 /*
  *		Hash tables that index the relation cache
@@ -2120,7 +2118,6 @@ RelationCacheInitialize(void)
 	formrdesc(AttributeRelationName, Natts_pg_attribute, Desc_pg_attribute);
 	formrdesc(ProcedureRelationName, Natts_pg_proc, Desc_pg_proc);
 	formrdesc(TypeRelationName, Natts_pg_type, Desc_pg_type);
-	formrdesc(LogRelationName, Natts_pg_log, Desc_pg_log);
 
 	/*
 	 * init_irels() used to be called here. It is changed to be called in
@@ -2167,10 +2164,6 @@ RelationCacheInitializePhase2(void)
 		fixrdesc(AttributeRelationName);
 		fixrdesc(ProcedureRelationName);
 		fixrdesc(TypeRelationName);
-
-		/*
-		 * We don't bother to update the entries for pg_log.
-		 */
 	}
 }
 
diff --git a/src/backend/utils/init/globals.c b/src/backend/utils/init/globals.c
index 7dff67bffbc..935340ea01d 100644
--- a/src/backend/utils/init/globals.c
+++ b/src/backend/utils/init/globals.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/globals.c,v 1.58 2001/06/12 05:55:50 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/globals.c,v 1.59 2001/08/25 18:52:42 tgl Exp $
  *
  * NOTES
  *	  Globals used all over the place should be declared here and not
@@ -102,7 +102,6 @@ char	   *SharedSystemRelationNames[] = {
 	GroupRelationName,
 	GroupNameIndex,
 	GroupSysidIndex,
-	LogRelationName,
 	ShadowRelationName,
 	ShadowNameIndex,
 	ShadowSysidIndex,
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index dedd9a8e765..51bd00bec30 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.87 2001/06/16 22:58:16 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/postinit.c,v 1.88 2001/08/25 18:52:42 tgl Exp $
  *
  *
  *-------------------------------------------------------------------------
@@ -285,26 +285,15 @@ InitPostgres(const char *dbname, const char *username)
 		elog(FATAL, "InitPostgres: bad backend id %d", MyBackendId);
 
 	/*
-	 * Initialize the transaction system and the relation descriptor
-	 * cache. Note we have to make certain the lock manager is off while
-	 * we do this.
+	 * Initialize the transaction system override state.
 	 */
-	AmiTransactionOverride(IsBootstrapProcessingMode());
-	LockDisable(true);
+	AmiTransactionOverride(bootstrap);
 
 	/*
-	 * Part of the initialization processing done here sets a read lock on
-	 * pg_log.	Since locking is disabled the set doesn't have intended
-	 * effect of locking out writers, but this is ok, since we only lock
-	 * it to examine AMI transaction status, and this is never written
-	 * after initdb is done. -mer 15 June 1992
+	 * Initialize the relation descriptor cache.
+	 * The pre-allocated reldescs are created here.
 	 */
-	RelationCacheInitialize();	/* pre-allocated reldescs created here */
-
-	InitializeTransactionSystem();		/* pg_log,etc init/crash recovery
-										 * here */
-
-	LockDisable(false);
+	RelationCacheInitialize();
 
 	/*
 	 * Initialize the access methods. Does not touch files (?) - thomas
diff --git a/src/backend/utils/misc/database.c b/src/backend/utils/misc/database.c
index be56a6902ff..218114f7cf6 100644
--- a/src/backend/utils/misc/database.c
+++ b/src/backend/utils/misc/database.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/misc/Attic/database.c,v 1.47 2001/05/30 20:52:34 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/misc/Attic/database.c,v 1.48 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -193,7 +193,7 @@ GetRawDatabaseInfo(const char *name, Oid *db_id, char *path)
 			 * happens right here.	We cannot really determine if the
 			 * tuple is valid without checking transaction commit status,
 			 * and the only way to do that at init time is to paw over
-			 * pg_log by hand, too.  Instead of checking, we assume that
+			 * pg_clog by hand, too.  Instead of checking, we assume that
 			 * the inserting transaction committed, and that any deleting
 			 * transaction did also, unless shown otherwise by on-row
 			 * commit status bits.
diff --git a/src/backend/utils/time/tqual.c b/src/backend/utils/time/tqual.c
index c5fe5fd5162..5f5699c4458 100644
--- a/src/backend/utils/time/tqual.c
+++ b/src/backend/utils/time/tqual.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.40 2001/08/23 23:06:38 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.41 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -611,12 +611,12 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId XmaxRecent)
 	 * If the inserting transaction aborted, then the tuple was never visible
 	 * to any other transaction, so we can delete it immediately.
 	 *
-	 * NOTE: must check TransactionIdIsInProgress (which looks in shared mem)
+	 * NOTE: must check TransactionIdIsInProgress (which looks in PROC array)
 	 * before TransactionIdDidCommit/TransactionIdDidAbort (which look in
-	 * pg_log).  Otherwise we have a race condition where we might decide
+	 * pg_clog).  Otherwise we have a race condition where we might decide
 	 * that a just-committed transaction crashed, because none of the tests
-	 * succeed.  xact.c is careful to record commit/abort in pg_log before
-	 * it unsets MyProc->xid in shared memory.
+	 * succeed.  xact.c is careful to record commit/abort in pg_clog before
+	 * it unsets MyProc->xid in PROC array.
 	 */
 	if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
 	{
diff --git a/src/bin/initdb/initdb.sh b/src/bin/initdb/initdb.sh
index d82000a19ea..bbb014391a4 100644
--- a/src/bin/initdb/initdb.sh
+++ b/src/bin/initdb/initdb.sh
@@ -27,7 +27,7 @@
 # Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
 # Portions Copyright (c) 1994, Regents of the University of California
 #
-# $Header: /cvsroot/pgsql/src/bin/initdb/Attic/initdb.sh,v 1.133 2001/08/25 00:31:17 petere Exp $
+# $Header: /cvsroot/pgsql/src/bin/initdb/Attic/initdb.sh,v 1.134 2001/08/25 18:52:42 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -440,6 +440,12 @@ else
         mkdir "$PGDATA"/pg_xlog || exit_nicely
 	echo "ok"
     fi
+    if [ ! -d "$PGDATA"/pg_clog ]
+    then
+        $ECHO_N "creating directory $PGDATA/pg_clog... "$ECHO_C
+        mkdir "$PGDATA"/pg_clog || exit_nicely
+	echo "ok"
+    fi
 fi
 
 
diff --git a/src/bin/pg_dump/pg_upgrade b/src/bin/pg_dump/pg_upgrade
index 91cdb37667e..d6db12e9c8a 100755
--- a/src/bin/pg_dump/pg_upgrade
+++ b/src/bin/pg_dump/pg_upgrade
@@ -3,7 +3,7 @@
 # pg_upgrade: update a database without needing a full dump/reload cycle.
 # CAUTION: read the manual page before trying to use this!
 
-# $Header: /cvsroot/pgsql/src/bin/pg_dump/Attic/pg_upgrade,v 1.16 2000/12/18 16:30:07 momjian Exp $
+# $Header: /cvsroot/pgsql/src/bin/pg_dump/Attic/pg_upgrade,v 1.17 2001/08/25 18:52:42 tgl Exp $
 #
 # NOTE: we must be sure to update the version-checking code a few dozen lines
 # below for each new PostgreSQL release.
@@ -127,9 +127,9 @@ fi
 echo "Input script $INPUT complete, fixing row commit statuses..."
 
 # Now vacuum each result database to mark all system-table rows as committed,
-# because when pg_log is replaced with the saved version, the transaction
+# because when pg_clog is replaced with the saved version, the transaction
 # statuses will no longer match the data.  VACUUM will force the on-row
-# status flags to the right value so that pg_log will not matter anymore.
+# status flags to the right value so that pg_clog will not matter anymore.
 # Note: we used to try to do this as part of the previous step, but that
 # risks permissions problems if VACUUM is run as the wrong user.
 # Note: the initial VACUUM does template1, then we do everything else.
@@ -171,7 +171,7 @@ do
 	fi
 done
 
-mv -f $OLDDIR/pg_log data
+mv -f $OLDDIR/pg_clog data
 mv -f $OLDDIR/pg_variable data
 
 echo "You must stop/start the postmaster before doing anything else."
diff --git a/src/include/access/clog.h b/src/include/access/clog.h
new file mode 100644
index 00000000000..4e44e8036cf
--- /dev/null
+++ b/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 */
diff --git a/src/include/access/rmgr.h b/src/include/access/rmgr.h
index af721e9fe76..b658422fd2b 100644
--- a/src/include/access/rmgr.h
+++ b/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
diff --git a/src/include/access/transam.h b/src/include/access/transam.h
index 3833d97821a..f0d213361ac 100644
--- a/src/include/access/transam.h
+++ b/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;
 
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index abbe16ced38..a9c7b674a95 100644
--- a/src/include/access/xact.h
+++ b/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);
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 73a60b2e0ce..dd5f0284a12 100644
--- a/src/include/access/xlog.h
+++ b/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"
 
 
diff --git a/src/include/access/xlogdefs.h b/src/include/access/xlogdefs.h
index d6af5eb4989..916474bd970 100644
--- a/src/include/access/xlogdefs.h
+++ b/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;
 
diff --git a/src/include/access/xlogutils.h b/src/include/access/xlogutils.h
index b31184b76bb..b427c836498 100644
--- a/src/include/access/xlogutils.h
+++ b/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);
 
diff --git a/src/include/catalog/catname.h b/src/include/catalog/catname.h
index 2f2f2c90f44..804c672b281 100644
--- a/src/include/catalog/catname.h
+++ b/src/include/catalog/catname.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: catname.h,v 1.19 2001/05/14 20:30:21 momjian Exp $
+ * $Id: catname.h,v 1.20 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,7 +29,6 @@
 #define  LanguageRelationName "pg_language"
 #define  LargeObjectRelationName "pg_largeobject"
 #define  ListenerRelationName "pg_listener"
-#define  LogRelationName "pg_log"
 #define  OperatorClassRelationName "pg_opclass"
 #define  OperatorRelationName "pg_operator"
 #define  ProcedureRelationName "pg_proc"
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index ea296593735..58d43a65293 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: catversion.h,v 1.91 2001/08/21 16:36:05 tgl Exp $
+ * $Id: catversion.h,v 1.92 2001/08/25 18:52:42 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200108211
+#define CATALOG_VERSION_NO	200108241
 
 #endif
diff --git a/src/include/catalog/pg_attribute.h b/src/include/catalog/pg_attribute.h
index ad8dc3a6e59..eb1ba77235e 100644
--- a/src/include/catalog/pg_attribute.h
+++ b/src/include/catalog/pg_attribute.h
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pg_attribute.h,v 1.74 2001/08/10 18:57:40 tgl Exp $
+ * $Id: pg_attribute.h,v 1.75 2001/08/25 18:52:42 tgl Exp $
  *
  * NOTES
  *	  the genbki.sh script reads this file and generates .bki
@@ -474,25 +474,13 @@ DATA(insert ( 1259 cmax				29 0  4  -6 0 -1 -1 t p f i f f));
 DATA(insert ( 1259 tableoid			26 0  4  -7 0 -1 -1 t p f i f f));
 
 /* ----------------
- *		pg_log - this relation is modified by special purpose access
- *				  method code.	The following is garbage but is needed
- *				  so that the reldesc code works properly.
+ *		pg_xactlock - this is not a real relation, but is a placeholder
+ *				  to allow a relation OID to be used for transaction
+ *				  waits.  We need a pg_xactlock entry in pg_class only to
+ *				  ensure that that OID can never be allocated to a real
+ *				  table; and this entry is just to link to that one.
  * ----------------
  */
-#define Schema_pg_log \
-{ 1269, {"logfoo"},  26, 0, 4, 1, 0, -1, -1, true, 'p', false, 'i', false, false }
-
-DATA(insert ( 1269 logfoo			26 0  4   1 0 -1 -1 t p f i f f));
-
-/* ----------------
- *		pg_xactlock - this relation is modified by special purpose access
- *				  method code.	The following is garbage but is needed
- *				  so that the reldesc code works properly.
- * ----------------
- */
-#define Schema_pg_xactlock \
-{ 376, {"xactlockfoo"},  26, 0, 4, 1, 0, -1, -1, true, 'p', false, 'i', false, false }
-
 DATA(insert ( 376 xactlockfoo		26 0  4   1 0 -1 -1 t p f i f f));
 
 #endif	 /* PG_ATTRIBUTE_H */
diff --git a/src/include/catalog/pg_class.h b/src/include/catalog/pg_class.h
index 859bb9d1852..4f2708e3bd0 100644
--- a/src/include/catalog/pg_class.h
+++ b/src/include/catalog/pg_class.h
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pg_class.h,v 1.52 2001/08/10 18:57:40 tgl Exp $
+ * $Id: pg_class.h,v 1.53 2001/08/25 18:52:43 tgl Exp $
  *
  * NOTES
  *	  the genbki.sh script reads this file and generates .bki
@@ -144,8 +144,6 @@ DATA(insert OID = 1261 (  pg_group		87	PGUID 0 1261 0 0 0 0 f t r 3  0 0 0 0 0 f
 DESCR("");
 DATA(insert OID = 1262 (  pg_database	88	PGUID 0 1262 0 0 0 0 f t r 7  0 0 0 0 0 t f f f _null_ ));
 DESCR("");
-DATA(insert OID = 1269 (  pg_log		99	PGUID 0 1269 0 0 0 0 f t s 1  0 0 0 0 0 f f f f _null_ ));
-DESCR("");
 DATA(insert OID = 376  (  pg_xactlock	0	PGUID 0    0 0 0 0 0 f t s 1  0 0 0 0 0 f f f f _null_ ));
 DESCR("");
 
@@ -156,7 +154,6 @@ DESCR("");
 #define RelOid_pg_shadow		1260
 #define RelOid_pg_group			1261
 #define RelOid_pg_database		1262
-#define RelOid_pg_log			1269
 
 /* Xact lock pseudo-table */
 #define XactLockTableId			376
diff --git a/src/include/catalog/pg_log.h b/src/include/catalog/pg_log.h
deleted file mode 100644
index 951aaf0efce..00000000000
--- a/src/include/catalog/pg_log.h
+++ /dev/null
@@ -1,41 +0,0 @@
-/*-------------------------------------------------------------------------
- *
- * pg_log.h
- *	  the system log relation "pg_log" is not a "heap" relation.
- *	  it is automatically created by the transam/ code and the
- *	  information here is all bogus and is just here to make the
- *	  relcache code happy.
- *
- *
- * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
- * Portions Copyright (c) 1994, Regents of the University of California
- *
- * $Id: pg_log.h,v 1.9 2001/08/10 18:57:40 tgl Exp $
- *
- * NOTES
- *	  The structures and macros used by the transam/ code
- *	  to access pg_log should some day go here -cim 6/18/90
- *
- *-------------------------------------------------------------------------
- */
-#ifndef PG_LOG_H
-#define PG_LOG_H
-
-/* ----------------
- *		postgres.h contains the system type definintions and the
- *		CATALOG(), BOOTSTRAP and DATA() sugar words so this file
- *		can be read by both genbki.sh and the C compiler.
- * ----------------
- */
-
-CATALOG(pg_log) BOOTSTRAP BKI_WITHOUT_OIDS
-{
-	Oid			logfoo;
-} FormData_pg_log;
-
-typedef FormData_pg_log *Form_pg_log;
-
-#define Natts_pg_log			1
-#define Anum_pg_log_logfoo		1
-
-#endif	 /* PG_LOG_H */
diff --git a/src/include/catalog/pg_type.h b/src/include/catalog/pg_type.h
index ffad5a7fe05..d5e02020291 100644
--- a/src/include/catalog/pg_type.h
+++ b/src/include/catalog/pg_type.h
@@ -8,7 +8,7 @@
  * Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pg_type.h,v 1.109 2001/06/12 05:55:50 tgl Exp $
+ * $Id: pg_type.h,v 1.110 2001/08/25 18:52:43 tgl Exp $
  *
  * NOTES
  *	  the genbki.sh script reads this file and generates .bki
@@ -239,7 +239,6 @@ DATA(insert OID = 83 (	pg_class	 PGUID 4 4 t c t \054 1259 0 int4in int4out int4
 DATA(insert OID = 86 (	pg_shadow	 PGUID 4 4 t c t \054 1260 0 int4in int4out int4in int4out i p _null_));
 DATA(insert OID = 87 (	pg_group	 PGUID 4 4 t c t \054 1261 0 int4in int4out int4in int4out i p _null_));
 DATA(insert OID = 88 (	pg_database  PGUID 4 4 t c t \054 1262 0 int4in int4out int4in int4out i p _null_));
-DATA(insert OID = 99 (	pg_log		 PGUID 4 4 t c t \054 1269 0 int4in int4out int4in int4out i p _null_));
 
 /* OIDS 100 - 199 */
 
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index 53532424452..b38b1677a0d 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.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: bufpage.h,v 1.42 2001/05/14 22:06:41 momjian Exp $
+ * $Id: bufpage.h,v 1.43 2001/08/25 18:52:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,10 +54,6 @@
  * obviously, a page is not formatted before it is initialized with by
  * a call to PageInit.
  *
- * The contents of the special pg_log tables are raw disk blocks with
- * special formats.  these are the only "access methods" that need not
- * write disk pages.
- *
  * NOTES:
  *
  * linp1..N form an ItemId array.  ItemPointers point into this array