XLOG (and related) changes:

* Store two past checkpoint locations, not just one, in pg_control. On startup, we fall back to the older checkpoint if the newer one is unreadable. Also, a physical copy of the newest checkpoint record is kept in pg_control for possible use in disaster recovery (ie, complete loss of pg_xlog). Also add a version number for pg_control itself. Remove archdir from pg_control; it ought to be a GUC parameter, not a special case (not that it's implemented yet anyway). * Suppress successive checkpoint records when nothing has been entered in the WAL log since the last one. This is not so much to avoid I/O as to make it actually useful to keep track of the last two checkpoints. If the things are right next to each other then there's not a lot of redundancy gained... * Change CRC scheme to a true 64-bit CRC, not a pair of 32-bit CRCs on alternate bytes. Polynomial borrowed from ECMA DLT1 standard. * Fix XLOG record length handling so that it will work at BLCKSZ = 32k. * Change XID allocation to work more like OID allocation. (This is of dubious necessity, but I think it's a good idea anyway.) * Fix a number of minor bugs, such as off-by-one logic for XLOG file wraparound at the 4 gig mark. * Add documentation and clean up some coding infelicities; move file format declarations out to include files where planned contrib utilities can get at them. * Checkpoint will now occur every CHECKPOINT_SEGMENTS log segments or every CHECKPOINT_TIMEOUT seconds, whichever comes first. It is also possible to force a checkpoint by sending SIGUSR1 to the postmaster (undocumented feature...) * Defend against kill -9 postmaster by storing shmem block's key and ID in postmaster.pid lockfile, and checking at startup to ensure that no processes are still connected to old shmem block (if it still exists). * Switch backends to accept SIGQUIT rather than SIGUSR1 for emergency stop, for symmetry with postmaster and xlog utilities. Clean up signal handling in bootstrap.c so that xlog utilities launched by postmaster will react to signals better. * Standalone bootstrap now grabs lockfile in target directory, as added insurance against running it in parallel with live postmaster.
2025-11-12 05:01:15 +03:00 · 2001-03-13 01:17:06 +00:00
parent b246510ccc
commit 4d14fe0048
29 changed files with 2857 additions and 1428 deletions
--- a/src/backend/access/transam/transam.c
+++ b/src/backend/access/transam/transam.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.39 2001/01/24 19:42:51 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/transam.c,v 1.40 2001/03/13 01:17:05 tgl Exp $
 *
 * NOTES
 *	  This file contains the high level access-method interface to the
@@ -430,6 +430,7 @@ InitializeTransactionLog(void)
 		Assert(!IsUnderPostmaster && 
 				ShmemVariableCache->nextXid <= FirstTransactionId);
 		ShmemVariableCache->nextXid = FirstTransactionId;
+		ShmemVariableCache->xidCount = 0; /* force an XLOG rec right away */
 	}
 	else if (RecoveryCheckingEnabled())
 	{
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -6,7 +6,7 @@
 * Copyright (c) 2000, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.35 2001/01/24 19:42:51 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/varsup.c,v 1.36 2001/03/13 01:17:05 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -14,12 +14,17 @@
 #include "postgres.h"

 #include "access/transam.h"
+#include "access/xlog.h"
 #include "storage/proc.h"

-SPINLOCK OidGenLockId;

-extern SPINLOCK XidGenLockId;
-extern void XLogPutNextOid(Oid nextOid);
+/* Number of XIDs and OIDs to prefetch (preallocate) per XLOG write */
+#define VAR_XID_PREFETCH		1024
+#define VAR_OID_PREFETCH		8192
+
+/* Spinlocks for serializing generation of XIDs and OIDs, respectively */
+SPINLOCK XidGenLockId;
+SPINLOCK OidGenLockId;

 /* pointer to "variable cache" in shared memory (set up by shmem.c) */
 VariableCache ShmemVariableCache = NULL;
@@ -38,23 +43,31 @@ GetNewTransactionId(TransactionId *xid)
 	}

 	SpinAcquire(XidGenLockId);
-	*xid = ShmemVariableCache->nextXid;
-	(ShmemVariableCache->nextXid)++;

-	if (MyProc != (PROC *) NULL)
-		MyProc->xid = *xid;
+	/* If we run out of logged for use xids then we must log more */
+	if (ShmemVariableCache->xidCount == 0)
+	{
+		XLogPutNextXid(ShmemVariableCache->nextXid + VAR_XID_PREFETCH);
+		ShmemVariableCache->xidCount = VAR_XID_PREFETCH;
+	}
+
+	*xid = ShmemVariableCache->nextXid;
+
+	(ShmemVariableCache->nextXid)++;
+	(ShmemVariableCache->xidCount)--;

 	SpinRelease(XidGenLockId);

+	if (MyProc != (PROC *) NULL)
+		MyProc->xid = *xid;
 }

 /*
- * Like GetNewTransactionId reads nextXid but don't fetch it.
+ * Read nextXid but don't allocate it.
 */
 void
 ReadNewTransactionId(TransactionId *xid)
 {
-
 	/*
 	 * During bootstrap initialization, we return the special
 	 * bootstrap transaction id.
@@ -68,7 +81,6 @@ ReadNewTransactionId(TransactionId *xid)
 	SpinAcquire(XidGenLockId);
 	*xid = ShmemVariableCache->nextXid;
 	SpinRelease(XidGenLockId);
-
 }

 /* ----------------------------------------------------------------
@@ -76,7 +88,6 @@ ReadNewTransactionId(TransactionId *xid)
 * ----------------------------------------------------------------
 */

-#define VAR_OID_PREFETCH		8192
 static Oid lastSeenOid = InvalidOid;

 void
@@ -84,7 +95,7 @@ GetNewObjectId(Oid *oid_return)
 {
 	SpinAcquire(OidGenLockId);

-	/* If we run out of logged for use oids then we log more */
+	/* If we run out of logged for use oids then we must log more */
 	if (ShmemVariableCache->oidCount == 0)
 	{
 		XLogPutNextOid(ShmemVariableCache->nextOid + VAR_OID_PREFETCH);
@@ -103,11 +114,11 @@ GetNewObjectId(Oid *oid_return)
 void
 CheckMaxObjectId(Oid assigned_oid)
 {
-
 	if (lastSeenOid != InvalidOid && assigned_oid < lastSeenOid)
 		return;

 	SpinAcquire(OidGenLockId);
+
 	if (assigned_oid < ShmemVariableCache->nextOid)
 	{
 		lastSeenOid = ShmemVariableCache->nextOid - 1;
@@ -138,5 +149,4 @@ CheckMaxObjectId(Oid assigned_oid)
 	ShmemVariableCache->nextOid = assigned_oid + 1;

 	SpinRelease(OidGenLockId);
-
 }
--- 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 1.98 2001/02/26 00:50:07 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/access/transam/xact.c,v 1.99 2001/03/13 01:17:05 tgl Exp $
 *
 * NOTES
 *		Transaction aborts can now occur two ways:
@@ -706,14 +706,18 @@ RecordTransactionCommit()
 		}

 		XLogFlush(recptr);
+
+		/* Break the chain of back-links in the XLOG records I output */
 		MyLastRecPtr.xrecoff = 0;

 		TransactionIdCommit(xid);

-		MyProc->logRec.xrecoff = 0;
 		END_CRIT_SECTION();
 	}

+	/* Show myself as out of the transaction in PROC array */
+	MyProc->logRec.xrecoff = 0;
+
 	if (leak)
 		ResetBufferPool(true);
 }
@@ -802,6 +806,10 @@ RecordTransactionAbort(void)
 {
 	TransactionId xid = GetCurrentTransactionId();

+	/*
+	 * Double check here is to catch case that we aborted partway through
+	 * RecordTransactionCommit ...
+	 */
 	if (MyLastRecPtr.xrecoff != 0 && !TransactionIdDidCommit(xid))
 	{
 		XLogRecData		rdata;
@@ -815,13 +823,19 @@ RecordTransactionAbort(void)
 		rdata.next = NULL;

 		START_CRIT_SECTION();
+
 		recptr = XLogInsert(RM_XACT_ID, XLOG_XACT_ABORT, &rdata);

 		TransactionIdAbort(xid);
-		MyProc->logRec.xrecoff = 0;
+
 		END_CRIT_SECTION();
 	}

+	/* Break the chain of back-links in the XLOG records I output */
+	MyLastRecPtr.xrecoff = 0;
+	/* Show myself as out of the transaction in PROC array */
+	MyProc->logRec.xrecoff = 0;
+
 	/*
 	 * Tell bufmgr and smgr to release resources.
 	 */
@@ -1187,10 +1201,6 @@ AbortTransaction(void)
 	AtEOXact_CatCache(false);
 	AtAbort_Memory();
 	AtEOXact_Files();
-
-	/* Here we'll rollback xaction changes */
-	MyLastRecPtr.xrecoff = 0;
-
 	AtAbort_Locks();

 	SharedBufferChanged = false; /* safest place to do it */
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -6,10 +6,12 @@
 * 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 1.14 2001/03/13 01:17:05 tgl Exp $
+ *
 *-------------------------------------------------------------------------
 */
-
 #include "postgres.h"
+
 #include "access/xlog.h"
 #include "access/transam.h"
 #include "access/xact.h"
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -8,7 +8,7 @@
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.104 2001/01/24 19:42:51 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/bootstrap/bootstrap.c,v 1.105 2001/03/13 01:17:05 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -18,13 +18,12 @@
 #include <time.h>
 #include <signal.h>
 #include <setjmp.h>
-
-#define BOOTSTRAP_INCLUDE		/* mask out stuff in tcop/tcopprot.h */
-
 #ifdef HAVE_GETOPT_H
 #include <getopt.h>
 #endif

+#define BOOTSTRAP_INCLUDE		/* mask out stuff in tcop/tcopprot.h */
+
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "access/xlog.h"
@@ -147,8 +146,6 @@ static MemoryContext nogc = NULL; /* special no-gc mem context */
 extern int	optind;
 extern char *optarg;

-extern void SetRedoRecPtr(void);
-
 /*
 *	At bootstrap time, we first declare all the indices to be built, and
 *	then build them.  The IndexList structure stores enough information
@@ -294,8 +291,16 @@ BootstrapMain(int argc, char *argv[])
 	else if (argc - optind == 1)
 		dbName = argv[optind];

-	SetProcessingMode(BootstrapProcessing);
-	IgnoreSystemIndexes(true);
+	if (dbName == NULL)
+	{
+		dbName = getenv("USER");
+		if (dbName == NULL)
+		{
+			fputs("bootstrap backend: failed, no db name specified\n", stderr);
+			fputs("          and no USER enviroment variable\n", stderr);
+			proc_exit(1);
+		}
+	}

 	if (!IsUnderPostmaster)
 	{
@@ -312,29 +317,52 @@ BootstrapMain(int argc, char *argv[])
 	}
 	Assert(DataDir);

-	if (dbName == NULL)
+	if (IsUnderPostmaster)
 	{
-		dbName = getenv("USER");
-		if (dbName == NULL)
-		{
-			fputs("bootstrap backend: failed, no db name specified\n", stderr);
-			fputs("          and no USER enviroment variable\n", stderr);
-			proc_exit(1);
-		}
+		/*
+		 * Properly accept or ignore signals the postmaster might send us
+		 */
+		pqsignal(SIGHUP, SIG_IGN);
+		pqsignal(SIGINT, SIG_IGN); /* ignore query-cancel */
+		pqsignal(SIGTERM, die);
+		pqsignal(SIGQUIT, quickdie);
+		pqsignal(SIGUSR1, SIG_IGN);
+		pqsignal(SIGUSR2, SIG_IGN);
+		/*
+		 * Reset some signals that are accepted by postmaster but not here
+		 */
+		pqsignal(SIGCHLD, SIG_IGN);
+		pqsignal(SIGTTIN, SIG_DFL);
+		pqsignal(SIGTTOU, SIG_DFL);
+		pqsignal(SIGCONT, SIG_DFL);
+		pqsignal(SIGWINCH, SIG_DFL);
+		/*
+		 * Unblock signals (they were blocked when the postmaster forked us)
+		 */
+		PG_SETMASK(&UnBlockSig);
 	}
-
-	XLOGPathInit();
-
-	BaseInit();
-
-	if (!IsUnderPostmaster)
+	else
 	{
+		/* Set up appropriately for interactive use */
 		pqsignal(SIGHUP, die);
 		pqsignal(SIGINT, die);
 		pqsignal(SIGTERM, die);
 		pqsignal(SIGQUIT, die);
+
+		/*
+		 * Create lockfile for data directory.
+		 */
+		if (! CreateDataDirLockFile(DataDir, false))
+			proc_exit(1);
 	}

+	SetProcessingMode(BootstrapProcessing);
+	IgnoreSystemIndexes(true);
+
+	XLOGPathInit();
+
+	BaseInit();
+
 	/*
 	 * XLOG operations
 	 */
--- a/src/backend/port/beos/shm.c
+++ b/src/backend/port/beos/shm.c
@@ -57,12 +57,25 @@ int* shmat(int memId,int m1,int m2)
 	}
 }

-/* Control a shared mem area : Used only to delete it */
-int shmctl(int shmid,int flag, struct shmid_ds* dummy)
+/* Control a shared mem area */
+int shmctl(int shmid, int flag, struct shmid_ds* dummy)
 {
-	/* Delete the area */
-	delete_area(shmid);
-	return 0;
+	if (flag == IPC_RMID)
+	{
+		/* Delete the area */
+		delete_area(shmid);
+		return 0;
+	}
+	if (flag == IPC_STAT)
+	{
+		/* Is there a way to check existence of an area given its ID?
+		 * For now, punt and assume it does not exist.
+		 */
+		errno = EINVAL;
+		return -1;
+	}
+	errno = EINVAL;
+	return -1;
 }

 /* Get an area based on the IPC key */
--- a/src/backend/port/qnx4/shm.c
+++ b/src/backend/port/qnx4/shm.c
@@ -7,7 +7,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/shm.c,v 1.2 2000/04/12 17:15:30 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/port/qnx4/Attic/shm.c,v 1.3 2001/03/13 01:17:06 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -173,20 +173,25 @@ shmctl(int shmid, int cmd, struct shmid_ds * buf)
 	struct shm_info info;
 	char		name[NAME_MAX + 1];

-	/* IPC_RMID supported only */
-	if (cmd != IPC_RMID)
+	if (cmd == IPC_RMID)
 	{
+		if (shm_getinfo(shmid, &info) == -1)
+		{
+			errno = EACCES;
+			return -1;
+		}
+		return shm_unlink(itoa(info.key, name, 16));
+	}
+	if (cmd == IPC_STAT)
+	{
+		/* Can we support IPC_STAT?  We only need shm_nattch ...
+		 * For now, punt and assume the shm seg does not exist.
+		 */
 		errno = EINVAL;
 		return -1;
 	}
-
-	if (shm_getinfo(shmid, &info) == -1)
-	{
-		errno = EACCES;
-		return -1;
-	}
-
-	return shm_unlink(itoa(info.key, name, 16));
+	errno = EINVAL;
+	return -1;
 }

 int
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -6,12 +6,29 @@
 *	  to the Postmaster and the postmaster uses the info in the
 *	  message to setup a backend process.
 *
+ *	  The postmaster also manages system-wide operations such as
+ *	  startup, shutdown, and periodic checkpoints.  The postmaster
+ *	  itself doesn't do those operations, mind you --- it just forks
+ *	  off a subprocess to do them at the right times.  It also takes
+ *	  care of resetting the system if a backend crashes.
+ *
+ *	  The postmaster process creates the shared memory and semaphore
+ *	  pools during startup, but as a rule does not touch them itself.
+ *	  In particular, it is not a member of the PROC array of backends
+ *	  and so it cannot participate in lock-manager operations.  Keeping
+ *	  the postmaster away from shared memory operations makes it simpler
+ *	  and more reliable.  The postmaster is almost always able to recover
+ *	  from crashes of individual backends by resetting shared memory;
+ *	  if it did much with shared memory then it would be prone to crashing
+ *	  along with the backends.
+ *
+ *
 * 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/postmaster/postmaster.c,v 1.208 2001/02/20 01:34:40 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.209 2001/03/13 01:17:05 tgl Exp $
 *
 * NOTES
 *
@@ -21,16 +38,15 @@
 *		lock manager.
 *
 * Synchronization:
- *		The Postmaster shares memory with the backends and will have to lock
- *		the shared memory it accesses.	The Postmaster should never block
- *		on messages from clients.
+ *		The Postmaster shares memory with the backends but should avoid
+ *		touching shared memory, so as not to become stuck if a crashing
+ *		backend screws up locks or shared memory.  Likewise, the Postmaster
+ *		should never block on messages from frontend clients.
 *
 * Garbage Collection:
 *		The Postmaster cleans up after backends if they have an emergency
 *		exit and/or core dump.
 *
- * Communication:
- *
 *-------------------------------------------------------------------------
 */

@@ -194,8 +210,6 @@ extern char *optarg;
 extern int	optind,
 			opterr;

-extern void GetRedoRecPtr(void);
-
 /*
 * postmaster.c - function prototypes
 */
@@ -207,6 +221,7 @@ static void reset_shared(unsigned short port);
 static void SIGHUP_handler(SIGNAL_ARGS);
 static void pmdie(SIGNAL_ARGS);
 static void reaper(SIGNAL_ARGS);
+static void schedule_checkpoint(SIGNAL_ARGS);
 static void dumpstatus(SIGNAL_ARGS);
 static void CleanupProc(int pid, int exitstatus);
 static int	DoBackend(Port *port);
@@ -491,7 +506,7 @@ PostmasterMain(int argc, char *argv[])

 				/*
 				 * In the event that some backend dumps core, send
-				 * SIGSTOP, rather than SIGUSR1, to all its peers.	This
+				 * SIGSTOP, rather than SIGQUIT, to all its peers.	This
 				 * lets the wily post_hacker collect core dumps from
 				 * everyone.
 				 */
@@ -643,11 +658,11 @@ PostmasterMain(int argc, char *argv[])

 	pqsignal(SIGHUP, SIGHUP_handler);	/* reread config file and have children do same */
 	pqsignal(SIGINT, pmdie);	/* send SIGTERM and ShutdownDataBase */
-	pqsignal(SIGQUIT, pmdie);	/* send SIGUSR1 and die */
+	pqsignal(SIGQUIT, pmdie);	/* send SIGQUIT and die */
 	pqsignal(SIGTERM, pmdie);	/* wait for children and ShutdownDataBase */
 	pqsignal(SIGALRM, SIG_IGN); /* ignored */
 	pqsignal(SIGPIPE, SIG_IGN); /* ignored */
-	pqsignal(SIGUSR1, pmdie);	/* currently ignored, but see note in pmdie */
+	pqsignal(SIGUSR1, schedule_checkpoint);	/* start a background checkpoint */
 	pqsignal(SIGUSR2, pmdie);	/* send SIGUSR2, don't die */
 	pqsignal(SIGCHLD, reaper);	/* handle child termination */
 	pqsignal(SIGTTIN, SIG_IGN); /* ignored */
@@ -773,25 +788,22 @@ ServerLoop(void)
 		struct timeval *timeout = NULL;
 		struct timeval	timeout_tv;

-		if (CheckPointPID == 0 && checkpointed && !FatalError)
+		if (CheckPointPID == 0 && checkpointed &&
+			Shutdown == NoShutdown && !FatalError)
 		{
 			time_t	now = time(NULL);

 			if (CheckPointTimeout + checkpointed > now)
 			{
+				/* Not time for checkpoint yet, so set a timeout for select */
 				timeout_tv.tv_sec = CheckPointTimeout + checkpointed - now;
 				timeout_tv.tv_usec = 0;
 				timeout = &timeout_tv;
 			}
 			else
 			{
+				/* Time to make the checkpoint... */
 				CheckPointPID = CheckPointDataBase();
-				/*
-				 * Since this code is executed periodically, it's a fine
-				 * place to do other actions that should happen every now
-				 * and then on no particular schedule.  Such as...
-				 */
-				TouchSocketLockFile();
 			}
 		}

@@ -1256,7 +1268,7 @@ ConnCreate(int serverFd)
 	{
 		fprintf(stderr, "%s: ConnCreate: malloc failed\n",
 				progname);
-		SignalChildren(SIGUSR1);
+		SignalChildren(SIGQUIT);
 		ExitPostmaster(1);
 	}

@@ -1374,7 +1386,7 @@ SIGHUP_handler(SIGNAL_ARGS)


 /*
- * pmdie -- signal handler for cleaning up after a kill signal.
+ * pmdie -- signal handler for processing various postmaster signals.
 */
 static void
 pmdie(SIGNAL_ARGS)
@@ -1388,18 +1400,6 @@ pmdie(SIGNAL_ARGS)

 	switch (postgres_signal_arg)
 	{
-		case SIGUSR1:
-			/*
-			 * Currently the postmaster ignores SIGUSR1 (maybe it should
-			 * do something useful instead?)  But we must have some handler
-			 * installed for SIGUSR1, not just set it to SIG_IGN.  Else, a
-			 * freshly spawned backend would likewise have it set to SIG_IGN,
-			 * which would mean the backend would ignore any attempt to kill
-			 * it before it had gotten as far as setting up its own handler.
-			 */
-			errno = save_errno;
-			return;
-
 		case SIGUSR2:

 			/*
@@ -1419,7 +1419,7 @@ pmdie(SIGNAL_ARGS)
 			/*
 			 * Smart Shutdown:
 			 *
-			 * let children to end their work and ShutdownDataBase.
+			 * Wait for children to end their work and ShutdownDataBase.
 			 */
 			if (Shutdown >= SmartShutdown)
 			{
@@ -1458,7 +1458,7 @@ pmdie(SIGNAL_ARGS)
 			 * Fast Shutdown:
 			 *
 			 * abort all children with SIGTERM (rollback active transactions
-			 * and exit) and ShutdownDataBase.
+			 * and exit) and ShutdownDataBase when they are gone.
 			 */
 			if (Shutdown >= FastShutdown)
 			{
@@ -1509,7 +1509,7 @@ pmdie(SIGNAL_ARGS)
 			/*
 			 * Immediate Shutdown:
 			 *
-			 * abort all children with SIGUSR1 and exit without attempt to
+			 * abort all children with SIGQUIT and exit without attempt to
 			 * properly shutdown data base system.
 			 */
 			tnow = time(NULL);
@@ -1517,10 +1517,10 @@ pmdie(SIGNAL_ARGS)
 			fflush(stderr);
 			if (ShutdownPID > 0)
 				kill(ShutdownPID, SIGQUIT);
-			else if (StartupPID > 0)
+			if (StartupPID > 0)
 				kill(StartupPID, SIGQUIT);
-			else if (DLGetHead(BackendList))
-				SignalChildren(SIGUSR1);
+			if (DLGetHead(BackendList))
+				SignalChildren(SIGQUIT);
 			break;
 	}

@@ -1593,11 +1593,13 @@ reaper(SIGNAL_ARGS)
 			}

 			/*
-			 * Startup succeeded - remember its ID
-			 * and RedoRecPtr
+			 * Startup succeeded - remember its ID and RedoRecPtr
 			 */
 			SetThisStartUpID();

+			/*
+			 * Arrange for first checkpoint to occur after standard delay.
+			 */
 			CheckPointPID = 0;
 			checkpointed = time(NULL);

@@ -1697,6 +1699,7 @@ CleanupProc(int pid,
 			if (!FatalError)
 			{
 				checkpointed = time(NULL);
+				/* Update RedoRecPtr for future child backends */
 				GetRedoRecPtr();
 			}
 		}
@@ -1731,7 +1734,7 @@ CleanupProc(int pid,
 			 * This backend is still alive.  Unless we did so already,
 			 * tell it to commit hara-kiri.
 			 *
-			 * SIGUSR1 is the special signal that says exit without proc_exit
+			 * SIGQUIT is the special signal that says exit without proc_exit
 			 * and let the user know what's going on. But if SendStop is set
 			 * (-s on command line), then we send SIGSTOP instead, so that we
 			 * can get core dumps from all backends by hand.
@@ -1741,9 +1744,9 @@ CleanupProc(int pid,
 				if (DebugLvl)
 					fprintf(stderr, "%s: CleanupProc: sending %s to process %d\n",
 							progname,
-							(SendStop ? "SIGSTOP" : "SIGUSR1"),
+							(SendStop ? "SIGSTOP" : "SIGQUIT"),
 							bp->pid);
-				kill(bp->pid, (SendStop ? SIGSTOP : SIGUSR1));
+				kill(bp->pid, (SendStop ? SIGSTOP : SIGQUIT));
 			}
 		}
 		else
@@ -1772,7 +1775,7 @@ CleanupProc(int pid,
 }

 /*
- * Send a signal to all chidren processes.
+ * Send a signal to all backend children.
 */
 static void
 SignalChildren(int signal)
@@ -2108,6 +2111,24 @@ ExitPostmaster(int status)
 	proc_exit(status);
 }

+/* Request to schedule a checkpoint (no-op if one is currently running) */
+static void
+schedule_checkpoint(SIGNAL_ARGS)
+{
+	int			save_errno = errno;
+
+	PG_SETMASK(&BlockSig);
+
+	/* Ignore request if checkpointing is currently disabled */
+	if (CheckPointPID == 0 && checkpointed &&
+		Shutdown == NoShutdown && !FatalError)
+	{
+		CheckPointPID = CheckPointDataBase();
+	}
+
+	errno = save_errno;
+}
+
 static void
 dumpstatus(SIGNAL_ARGS)
 {
@@ -2116,12 +2137,13 @@ dumpstatus(SIGNAL_ARGS)

 	PG_SETMASK(&BlockSig);

+	fprintf(stderr, "%s: dumpstatus:\n", progname);
+
 	curr = DLGetHead(PortList);
 	while (curr)
 	{
 		Port	   *port = DLE_VAL(curr);

-		fprintf(stderr, "%s: dumpstatus:\n", progname);
 		fprintf(stderr, "\tsock %d\n", port->sock);
 		curr = DLGetSucc(curr);
 	}
@@ -2240,6 +2262,9 @@ InitSSL(void)

 #endif

+/*
+ * Fire off a subprocess for startup/shutdown/checkpoint.
+ */
 static pid_t
 SSDataBase(int xlop)
 {
@@ -2273,7 +2298,7 @@ SSDataBase(int xlop)
 		/* Close the postmaster's sockets */
 		ClosePostmasterPorts(NULL);

-
+		/* Set up command-line arguments for subprocess */
 		av[ac++] = "postgres";

 		av[ac++] = "-d";
@@ -2293,14 +2318,6 @@ SSDataBase(int xlop)

 		optind = 1;

-		pqsignal(SIGQUIT, SIG_DFL);
-#ifdef HAVE_SIGPROCMASK
-		sigdelset(&BlockSig, SIGQUIT);
-#else
-		BlockSig &= ~(sigmask(SIGQUIT));
-#endif
-		PG_SETMASK(&BlockSig);
-
 		BootstrapMain(ac, av);
 		ExitPostmaster(0);
 	}
@@ -2320,19 +2337,31 @@ SSDataBase(int xlop)
 		ExitPostmaster(1);
 	}

-	if (xlop != BS_XLOG_CHECKPOINT)
-		return(pid);
-
-	if (!(bn = (Backend *) calloc(1, sizeof(Backend))))
+	/*
+	 * The startup and shutdown processes are not considered normal backends,
+	 * but the checkpoint process is.  Checkpoint must be added to the list
+	 * of backends.
+	 */
+	if (xlop == BS_XLOG_CHECKPOINT)
 	{
-		fprintf(stderr, "%s: CheckPointDataBase: malloc failed\n",
-				progname);
-		ExitPostmaster(1);
-	}
+		if (!(bn = (Backend *) calloc(1, sizeof(Backend))))
+		{
+			fprintf(stderr, "%s: CheckPointDataBase: malloc failed\n",
+					progname);
+			ExitPostmaster(1);
+		}

-	bn->pid = pid;
-	bn->cancel_key = 0;
-	DLAddHead(BackendList, DLNewElem(bn));
+		bn->pid = pid;
+		bn->cancel_key = PostmasterRandom();
+		DLAddHead(BackendList, DLNewElem(bn));
+
+		/*
+		 * Since this code is executed periodically, it's a fine
+		 * place to do other actions that should happen every now
+		 * and then on no particular schedule.  Such as...
+		 */
+		TouchSocketLockFile();
+	}

 	return (pid);
 }
--- a/src/backend/storage/ipc/ipc.c
+++ b/src/backend/storage/ipc/ipc.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipc.c,v 1.62 2001/01/24 19:43:07 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/ipc/ipc.c,v 1.63 2001/03/13 01:17:06 tgl Exp $
 *
 * NOTES
 *
@@ -626,6 +626,9 @@ InternalIpcMemoryCreate(IpcMemoryKey memKey, uint32 size, int permission)
 	/* Register on-exit routine to detach new segment before deleting */
 	on_shmem_exit(IpcMemoryDetach, PointerGetDatum(memAddress));

+	/* Record key and ID in lockfile for data directory. */
+	RecordSharedMemoryInLockFile(memKey, shmid);
+
 	return memAddress;
 }

@@ -660,6 +663,41 @@ IpcMemoryDelete(int status, Datum shmId)
 	 */
 }

+/****************************************************************************/
+/*	SharedMemoryIsInUse(shmKey, shmId)	Is a shared memory segment in use?	*/
+/****************************************************************************/
+bool
+SharedMemoryIsInUse(IpcMemoryKey shmKey, IpcMemoryId shmId)
+{
+	struct shmid_ds		shmStat;
+
+	/*
+	 * We detect whether a shared memory segment is in use by seeing whether
+	 * it (a) exists and (b) has any processes are attached to it.
+	 *
+	 * If we are unable to perform the stat operation for a reason other than
+	 * nonexistence of the segment (most likely, because it doesn't belong to
+	 * our userid), assume it is in use.
+	 */
+	if (shmctl(shmId, IPC_STAT, &shmStat) < 0)
+	{
+		/*
+		 * EINVAL actually has multiple possible causes documented in the
+		 * shmctl man page, but we assume it must mean the segment no longer
+		 * exists.
+		 */
+		if (errno == EINVAL)
+			return false;
+		/* Else assume segment is in use */
+		return true;
+	}
+	/* If it has attached processes, it's in use */
+	if (shmStat.shm_nattch != 0)
+		return true;
+	return false;
+}
+
+
 /* ----------------------------------------------------------------
 *						private memory support
 *
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.209 2001/03/09 06:36:32 inoue Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.210 2001/03/13 01:17:06 tgl Exp $
 *
 * NOTES
 *	  this is the "main" module of the postgres backend and
@@ -128,7 +128,6 @@ static void start_xact_command(void);
 static void finish_xact_command(void);
 static void SigHupHandler(SIGNAL_ARGS);
 static void FloatExceptionHandler(SIGNAL_ARGS);
-static void quickdie(SIGNAL_ARGS);

 /*
 * Flag to mark SIGHUP. Whenever the main loop comes around it
@@ -895,12 +894,12 @@ finish_xact_command(void)
 */

 /*
- * quickdie() occurs when signalled SIGUSR1 by the postmaster.
+ * quickdie() occurs when signalled SIGQUIT by the postmaster.
 *
 * Some backend has bought the farm,
 * so we need to stop what we're doing and exit.
 */
-static void
+void
 quickdie(SIGNAL_ARGS)
 {
 	PG_SETMASK(&BlockSig);
@@ -917,7 +916,7 @@ quickdie(SIGNAL_ARGS)
 	 * Just nail the windows shut and get out of town.
 	 *
 	 * Note we do exit(1) not exit(0).  This is to force the postmaster
-	 * into a system reset cycle if some idiot DBA sends a manual SIGUSR1
+	 * into a system reset cycle if some idiot DBA sends a manual SIGQUIT
 	 * to a random backend.  This is necessary precisely because we don't
 	 * clean up our shared memory state.
 	 */
@@ -987,8 +986,8 @@ QueryCancelHandler(SIGNAL_ARGS)
 			InterruptHoldoffCount++;
 			if (LockWaitCancel())
 			{
-				InterruptHoldoffCount--;
 				DisableNotifyInterrupt();
+				InterruptHoldoffCount--;
 				ProcessInterrupts();
 			}
 			else
@@ -1205,9 +1204,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha

 			case 'D':			/* PGDATA directory */
 				if (secure)
-				{
 					potential_DataDir = optarg;
-				}
 				break;

 			case 'd':			/* debug level */
@@ -1243,13 +1240,10 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
 			case 'F':
 				/* --------------------
 				 *	turn off fsync
-				 *
-				 *	7.0 buffer manager can support different backends running
-				 *	with different fsync settings, so this no longer needs
-				 *	to be "if (secure)".
 				 * --------------------
 				 */
-				enableFsync = false;
+				if (secure)
+					enableFsync = false;
 				break;

 			case 'f':
@@ -1504,13 +1498,18 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
 	 * Note that postmaster blocked all signals before forking child process,
 	 * so there is no race condition whereby we might receive a signal before
 	 * we have set up the handler.
+	 *
+	 * Also note: it's best not to use any signals that are SIG_IGNored in
+	 * the postmaster.  If such a signal arrives before we are able to change
+	 * the handler to non-SIG_IGN, it'll get dropped.  If necessary, make a
+	 * dummy handler in the postmaster to reserve the signal.
 	 */

 	pqsignal(SIGHUP, SigHupHandler);	/* set flag to read config file */
 	pqsignal(SIGINT, QueryCancelHandler); /* cancel current query */
 	pqsignal(SIGTERM, die);		/* cancel current query and exit */
-	pqsignal(SIGQUIT, die);		/* could reassign this sig for another use */
-	pqsignal(SIGALRM, HandleDeadLock);
+	pqsignal(SIGQUIT, quickdie); /* hard crash time */
+	pqsignal(SIGALRM, HandleDeadLock); /* check for deadlock after timeout */

 	/*
 	 * Ignore failure to write to frontend. Note: if frontend closes
@@ -1519,7 +1518,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
 	 * midst of output during who-knows-what operation...
 	 */
 	pqsignal(SIGPIPE, SIG_IGN);
-	pqsignal(SIGUSR1, quickdie);
+	pqsignal(SIGUSR1, SIG_IGN);	/* this signal available for use */
 	pqsignal(SIGUSR2, Async_NotifyHandler);		/* flush also sinval cache */
 	pqsignal(SIGFPE, FloatExceptionHandler);
 	pqsignal(SIGCHLD, SIG_IGN);	/* ignored (may get this in system() calls) */
@@ -1534,14 +1533,14 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha

 	pqinitmask();

-	/* We allow SIGUSR1 (quickdie) at all times */
+	/* We allow SIGQUIT (quickdie) at all times */
 #ifdef HAVE_SIGPROCMASK
-	sigdelset(&BlockSig, SIGUSR1);
+	sigdelset(&BlockSig, SIGQUIT);
 #else
-	BlockSig &= ~(sigmask(SIGUSR1));
+	BlockSig &= ~(sigmask(SIGQUIT));
 #endif

-	PG_SETMASK(&BlockSig);		/* block everything except SIGUSR1 */
+	PG_SETMASK(&BlockSig);		/* block everything except SIGQUIT */


 	if (IsUnderPostmaster)
@@ -1693,7 +1692,7 @@ PostgresMain(int argc, char *argv[], int real_argc, char *real_argv[], const cha
 	if (!IsUnderPostmaster)
 	{
 		puts("\nPOSTGRES backend interactive interface ");
-		puts("$Revision: 1.209 $ $Date: 2001/03/09 06:36:32 $\n");
+		puts("$Revision: 1.210 $ $Date: 2001/03/13 01:17:06 $\n");
 	}

 	/*
--- a/src/backend/utils/hash/Makefile
+++ b/src/backend/utils/hash/Makefile
@@ -4,7 +4,7 @@
 #    Makefile for utils/hash
 #
 # IDENTIFICATION
-#    $Header: /cvsroot/pgsql/src/backend/utils/hash/Makefile,v 1.9 2000/08/31 16:10:51 petere Exp $
+#    $Header: /cvsroot/pgsql/src/backend/utils/hash/Makefile,v 1.10 2001/03/13 01:17:06 tgl Exp $
 #
 #-------------------------------------------------------------------------

@@ -12,7 +12,7 @@ subdir = src/backend/utils/hash
 top_builddir = ../../../..
 include $(top_builddir)/src/Makefile.global

-OBJS = dynahash.o hashfn.o
+OBJS = dynahash.o hashfn.o pg_crc.o

 all: SUBSYS.o

--- a/src/backend/utils/hash/pg_crc.c
+++ b/src/backend/utils/hash/pg_crc.c
@@ -0,0 +1,417 @@
+/*-------------------------------------------------------------------------
+ *
+ * pg_crc.c
+ *	  PostgreSQL 64-bit CRC support
+ *
+ * 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/utils/hash/pg_crc.c,v 1.1 2001/03/13 01:17:06 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "utils/pg_crc.h"
+
+
+#ifdef INT64_IS_BUSTED
+
+const uint32 crc_table0[256] = {
+	0x00000000, 0xA9EA3693,
+	0x53D46D26, 0xFA3E5BB5,
+	0x0E42ECDF, 0xA7A8DA4C,
+	0x5D9681F9, 0xF47CB76A,
+	0x1C85D9BE, 0xB56FEF2D,
+	0x4F51B498, 0xE6BB820B,
+	0x12C73561, 0xBB2D03F2,
+	0x41135847, 0xE8F96ED4,
+	0x90E185EF, 0x390BB37C,
+	0xC335E8C9, 0x6ADFDE5A,
+	0x9EA36930, 0x37495FA3,
+	0xCD770416, 0x649D3285,
+	0x8C645C51, 0x258E6AC2,
+	0xDFB03177, 0x765A07E4,
+	0x8226B08E, 0x2BCC861D,
+	0xD1F2DDA8, 0x7818EB3B,
+	0x21C30BDE, 0x88293D4D,
+	0x721766F8, 0xDBFD506B,
+	0x2F81E701, 0x866BD192,
+	0x7C558A27, 0xD5BFBCB4,
+	0x3D46D260, 0x94ACE4F3,
+	0x6E92BF46, 0xC77889D5,
+	0x33043EBF, 0x9AEE082C,
+	0x60D05399, 0xC93A650A,
+	0xB1228E31, 0x18C8B8A2,
+	0xE2F6E317, 0x4B1CD584,
+	0xBF6062EE, 0x168A547D,
+	0xECB40FC8, 0x455E395B,
+	0xADA7578F, 0x044D611C,
+	0xFE733AA9, 0x57990C3A,
+	0xA3E5BB50, 0x0A0F8DC3,
+	0xF031D676, 0x59DBE0E5,
+	0xEA6C212F, 0x438617BC,
+	0xB9B84C09, 0x10527A9A,
+	0xE42ECDF0, 0x4DC4FB63,
+	0xB7FAA0D6, 0x1E109645,
+	0xF6E9F891, 0x5F03CE02,
+	0xA53D95B7, 0x0CD7A324,
+	0xF8AB144E, 0x514122DD,
+	0xAB7F7968, 0x02954FFB,
+	0x7A8DA4C0, 0xD3679253,
+	0x2959C9E6, 0x80B3FF75,
+	0x74CF481F, 0xDD257E8C,
+	0x271B2539, 0x8EF113AA,
+	0x66087D7E, 0xCFE24BED,
+	0x35DC1058, 0x9C3626CB,
+	0x684A91A1, 0xC1A0A732,
+	0x3B9EFC87, 0x9274CA14,
+	0xCBAF2AF1, 0x62451C62,
+	0x987B47D7, 0x31917144,
+	0xC5EDC62E, 0x6C07F0BD,
+	0x9639AB08, 0x3FD39D9B,
+	0xD72AF34F, 0x7EC0C5DC,
+	0x84FE9E69, 0x2D14A8FA,
+	0xD9681F90, 0x70822903,
+	0x8ABC72B6, 0x23564425,
+	0x5B4EAF1E, 0xF2A4998D,
+	0x089AC238, 0xA170F4AB,
+	0x550C43C1, 0xFCE67552,
+	0x06D82EE7, 0xAF321874,
+	0x47CB76A0, 0xEE214033,
+	0x141F1B86, 0xBDF52D15,
+	0x49899A7F, 0xE063ACEC,
+	0x1A5DF759, 0xB3B7C1CA,
+	0x7D3274CD, 0xD4D8425E,
+	0x2EE619EB, 0x870C2F78,
+	0x73709812, 0xDA9AAE81,
+	0x20A4F534, 0x894EC3A7,
+	0x61B7AD73, 0xC85D9BE0,
+	0x3263C055, 0x9B89F6C6,
+	0x6FF541AC, 0xC61F773F,
+	0x3C212C8A, 0x95CB1A19,
+	0xEDD3F122, 0x4439C7B1,
+	0xBE079C04, 0x17EDAA97,
+	0xE3911DFD, 0x4A7B2B6E,
+	0xB04570DB, 0x19AF4648,
+	0xF156289C, 0x58BC1E0F,
+	0xA28245BA, 0x0B687329,
+	0xFF14C443, 0x56FEF2D0,
+	0xACC0A965, 0x052A9FF6,
+	0x5CF17F13, 0xF51B4980,
+	0x0F251235, 0xA6CF24A6,
+	0x52B393CC, 0xFB59A55F,
+	0x0167FEEA, 0xA88DC879,
+	0x4074A6AD, 0xE99E903E,
+	0x13A0CB8B, 0xBA4AFD18,
+	0x4E364A72, 0xE7DC7CE1,
+	0x1DE22754, 0xB40811C7,
+	0xCC10FAFC, 0x65FACC6F,
+	0x9FC497DA, 0x362EA149,
+	0xC2521623, 0x6BB820B0,
+	0x91867B05, 0x386C4D96,
+	0xD0952342, 0x797F15D1,
+	0x83414E64, 0x2AAB78F7,
+	0xDED7CF9D, 0x773DF90E,
+	0x8D03A2BB, 0x24E99428,
+	0x975E55E2, 0x3EB46371,
+	0xC48A38C4, 0x6D600E57,
+	0x991CB93D, 0x30F68FAE,
+	0xCAC8D41B, 0x6322E288,
+	0x8BDB8C5C, 0x2231BACF,
+	0xD80FE17A, 0x71E5D7E9,
+	0x85996083, 0x2C735610,
+	0xD64D0DA5, 0x7FA73B36,
+	0x07BFD00D, 0xAE55E69E,
+	0x546BBD2B, 0xFD818BB8,
+	0x09FD3CD2, 0xA0170A41,
+	0x5A2951F4, 0xF3C36767,
+	0x1B3A09B3, 0xB2D03F20,
+	0x48EE6495, 0xE1045206,
+	0x1578E56C, 0xBC92D3FF,
+	0x46AC884A, 0xEF46BED9,
+	0xB69D5E3C, 0x1F7768AF,
+	0xE549331A, 0x4CA30589,
+	0xB8DFB2E3, 0x11358470,
+	0xEB0BDFC5, 0x42E1E956,
+	0xAA188782, 0x03F2B111,
+	0xF9CCEAA4, 0x5026DC37,
+	0xA45A6B5D, 0x0DB05DCE,
+	0xF78E067B, 0x5E6430E8,
+	0x267CDBD3, 0x8F96ED40,
+	0x75A8B6F5, 0xDC428066,
+	0x283E370C, 0x81D4019F,
+	0x7BEA5A2A, 0xD2006CB9,
+	0x3AF9026D, 0x931334FE,
+	0x692D6F4B, 0xC0C759D8,
+	0x34BBEEB2, 0x9D51D821,
+	0x676F8394, 0xCE85B507
+};
+
+const uint32 crc_table1[256] = {
+	0x00000000, 0x42F0E1EB,
+	0x85E1C3D7, 0xC711223C,
+	0x49336645, 0x0BC387AE,
+	0xCCD2A592, 0x8E224479,
+	0x9266CC8A, 0xD0962D61,
+	0x17870F5D, 0x5577EEB6,
+	0xDB55AACF, 0x99A54B24,
+	0x5EB46918, 0x1C4488F3,
+	0x663D78FF, 0x24CD9914,
+	0xE3DCBB28, 0xA12C5AC3,
+	0x2F0E1EBA, 0x6DFEFF51,
+	0xAAEFDD6D, 0xE81F3C86,
+	0xF45BB475, 0xB6AB559E,
+	0x71BA77A2, 0x334A9649,
+	0xBD68D230, 0xFF9833DB,
+	0x388911E7, 0x7A79F00C,
+	0xCC7AF1FF, 0x8E8A1014,
+	0x499B3228, 0x0B6BD3C3,
+	0x854997BA, 0xC7B97651,
+	0x00A8546D, 0x4258B586,
+	0x5E1C3D75, 0x1CECDC9E,
+	0xDBFDFEA2, 0x990D1F49,
+	0x172F5B30, 0x55DFBADB,
+	0x92CE98E7, 0xD03E790C,
+	0xAA478900, 0xE8B768EB,
+	0x2FA64AD7, 0x6D56AB3C,
+	0xE374EF45, 0xA1840EAE,
+	0x66952C92, 0x2465CD79,
+	0x3821458A, 0x7AD1A461,
+	0xBDC0865D, 0xFF3067B6,
+	0x711223CF, 0x33E2C224,
+	0xF4F3E018, 0xB60301F3,
+	0xDA050215, 0x98F5E3FE,
+	0x5FE4C1C2, 0x1D142029,
+	0x93366450, 0xD1C685BB,
+	0x16D7A787, 0x5427466C,
+	0x4863CE9F, 0x0A932F74,
+	0xCD820D48, 0x8F72ECA3,
+	0x0150A8DA, 0x43A04931,
+	0x84B16B0D, 0xC6418AE6,
+	0xBC387AEA, 0xFEC89B01,
+	0x39D9B93D, 0x7B2958D6,
+	0xF50B1CAF, 0xB7FBFD44,
+	0x70EADF78, 0x321A3E93,
+	0x2E5EB660, 0x6CAE578B,
+	0xABBF75B7, 0xE94F945C,
+	0x676DD025, 0x259D31CE,
+	0xE28C13F2, 0xA07CF219,
+	0x167FF3EA, 0x548F1201,
+	0x939E303D, 0xD16ED1D6,
+	0x5F4C95AF, 0x1DBC7444,
+	0xDAAD5678, 0x985DB793,
+	0x84193F60, 0xC6E9DE8B,
+	0x01F8FCB7, 0x43081D5C,
+	0xCD2A5925, 0x8FDAB8CE,
+	0x48CB9AF2, 0x0A3B7B19,
+	0x70428B15, 0x32B26AFE,
+	0xF5A348C2, 0xB753A929,
+	0x3971ED50, 0x7B810CBB,
+	0xBC902E87, 0xFE60CF6C,
+	0xE224479F, 0xA0D4A674,
+	0x67C58448, 0x253565A3,
+	0xAB1721DA, 0xE9E7C031,
+	0x2EF6E20D, 0x6C0603E6,
+	0xF6FAE5C0, 0xB40A042B,
+	0x731B2617, 0x31EBC7FC,
+	0xBFC98385, 0xFD39626E,
+	0x3A284052, 0x78D8A1B9,
+	0x649C294A, 0x266CC8A1,
+	0xE17DEA9D, 0xA38D0B76,
+	0x2DAF4F0F, 0x6F5FAEE4,
+	0xA84E8CD8, 0xEABE6D33,
+	0x90C79D3F, 0xD2377CD4,
+	0x15265EE8, 0x57D6BF03,
+	0xD9F4FB7A, 0x9B041A91,
+	0x5C1538AD, 0x1EE5D946,
+	0x02A151B5, 0x4051B05E,
+	0x87409262, 0xC5B07389,
+	0x4B9237F0, 0x0962D61B,
+	0xCE73F427, 0x8C8315CC,
+	0x3A80143F, 0x7870F5D4,
+	0xBF61D7E8, 0xFD913603,
+	0x73B3727A, 0x31439391,
+	0xF652B1AD, 0xB4A25046,
+	0xA8E6D8B5, 0xEA16395E,
+	0x2D071B62, 0x6FF7FA89,
+	0xE1D5BEF0, 0xA3255F1B,
+	0x64347D27, 0x26C49CCC,
+	0x5CBD6CC0, 0x1E4D8D2B,
+	0xD95CAF17, 0x9BAC4EFC,
+	0x158E0A85, 0x577EEB6E,
+	0x906FC952, 0xD29F28B9,
+	0xCEDBA04A, 0x8C2B41A1,
+	0x4B3A639D, 0x09CA8276,
+	0x87E8C60F, 0xC51827E4,
+	0x020905D8, 0x40F9E433,
+	0x2CFFE7D5, 0x6E0F063E,
+	0xA91E2402, 0xEBEEC5E9,
+	0x65CC8190, 0x273C607B,
+	0xE02D4247, 0xA2DDA3AC,
+	0xBE992B5F, 0xFC69CAB4,
+	0x3B78E888, 0x79880963,
+	0xF7AA4D1A, 0xB55AACF1,
+	0x724B8ECD, 0x30BB6F26,
+	0x4AC29F2A, 0x08327EC1,
+	0xCF235CFD, 0x8DD3BD16,
+	0x03F1F96F, 0x41011884,
+	0x86103AB8, 0xC4E0DB53,
+	0xD8A453A0, 0x9A54B24B,
+	0x5D459077, 0x1FB5719C,
+	0x919735E5, 0xD367D40E,
+	0x1476F632, 0x568617D9,
+	0xE085162A, 0xA275F7C1,
+	0x6564D5FD, 0x27943416,
+	0xA9B6706F, 0xEB469184,
+	0x2C57B3B8, 0x6EA75253,
+	0x72E3DAA0, 0x30133B4B,
+	0xF7021977, 0xB5F2F89C,
+	0x3BD0BCE5, 0x79205D0E,
+	0xBE317F32, 0xFCC19ED9,
+	0x86B86ED5, 0xC4488F3E,
+	0x0359AD02, 0x41A94CE9,
+	0xCF8B0890, 0x8D7BE97B,
+	0x4A6ACB47, 0x089A2AAC,
+	0x14DEA25F, 0x562E43B4,
+	0x913F6188, 0xD3CF8063,
+	0x5DEDC41A, 0x1F1D25F1,
+	0xD80C07CD, 0x9AFCE626
+};
+
+#else /* int64 works */
+
+const uint64 crc_table[256] = {
+	0x0000000000000000, 0x42F0E1EBA9EA3693,
+	0x85E1C3D753D46D26, 0xC711223CFA3E5BB5,
+	0x493366450E42ECDF, 0x0BC387AEA7A8DA4C,
+	0xCCD2A5925D9681F9, 0x8E224479F47CB76A,
+	0x9266CC8A1C85D9BE, 0xD0962D61B56FEF2D,
+	0x17870F5D4F51B498, 0x5577EEB6E6BB820B,
+	0xDB55AACF12C73561, 0x99A54B24BB2D03F2,
+	0x5EB4691841135847, 0x1C4488F3E8F96ED4,
+	0x663D78FF90E185EF, 0x24CD9914390BB37C,
+	0xE3DCBB28C335E8C9, 0xA12C5AC36ADFDE5A,
+	0x2F0E1EBA9EA36930, 0x6DFEFF5137495FA3,
+	0xAAEFDD6DCD770416, 0xE81F3C86649D3285,
+	0xF45BB4758C645C51, 0xB6AB559E258E6AC2,
+	0x71BA77A2DFB03177, 0x334A9649765A07E4,
+	0xBD68D2308226B08E, 0xFF9833DB2BCC861D,
+	0x388911E7D1F2DDA8, 0x7A79F00C7818EB3B,
+	0xCC7AF1FF21C30BDE, 0x8E8A101488293D4D,
+	0x499B3228721766F8, 0x0B6BD3C3DBFD506B,
+	0x854997BA2F81E701, 0xC7B97651866BD192,
+	0x00A8546D7C558A27, 0x4258B586D5BFBCB4,
+	0x5E1C3D753D46D260, 0x1CECDC9E94ACE4F3,
+	0xDBFDFEA26E92BF46, 0x990D1F49C77889D5,
+	0x172F5B3033043EBF, 0x55DFBADB9AEE082C,
+	0x92CE98E760D05399, 0xD03E790CC93A650A,
+	0xAA478900B1228E31, 0xE8B768EB18C8B8A2,
+	0x2FA64AD7E2F6E317, 0x6D56AB3C4B1CD584,
+	0xE374EF45BF6062EE, 0xA1840EAE168A547D,
+	0x66952C92ECB40FC8, 0x2465CD79455E395B,
+	0x3821458AADA7578F, 0x7AD1A461044D611C,
+	0xBDC0865DFE733AA9, 0xFF3067B657990C3A,
+	0x711223CFA3E5BB50, 0x33E2C2240A0F8DC3,
+	0xF4F3E018F031D676, 0xB60301F359DBE0E5,
+	0xDA050215EA6C212F, 0x98F5E3FE438617BC,
+	0x5FE4C1C2B9B84C09, 0x1D14202910527A9A,
+	0x93366450E42ECDF0, 0xD1C685BB4DC4FB63,
+	0x16D7A787B7FAA0D6, 0x5427466C1E109645,
+	0x4863CE9FF6E9F891, 0x0A932F745F03CE02,
+	0xCD820D48A53D95B7, 0x8F72ECA30CD7A324,
+	0x0150A8DAF8AB144E, 0x43A04931514122DD,
+	0x84B16B0DAB7F7968, 0xC6418AE602954FFB,
+	0xBC387AEA7A8DA4C0, 0xFEC89B01D3679253,
+	0x39D9B93D2959C9E6, 0x7B2958D680B3FF75,
+	0xF50B1CAF74CF481F, 0xB7FBFD44DD257E8C,
+	0x70EADF78271B2539, 0x321A3E938EF113AA,
+	0x2E5EB66066087D7E, 0x6CAE578BCFE24BED,
+	0xABBF75B735DC1058, 0xE94F945C9C3626CB,
+	0x676DD025684A91A1, 0x259D31CEC1A0A732,
+	0xE28C13F23B9EFC87, 0xA07CF2199274CA14,
+	0x167FF3EACBAF2AF1, 0x548F120162451C62,
+	0x939E303D987B47D7, 0xD16ED1D631917144,
+	0x5F4C95AFC5EDC62E, 0x1DBC74446C07F0BD,
+	0xDAAD56789639AB08, 0x985DB7933FD39D9B,
+	0x84193F60D72AF34F, 0xC6E9DE8B7EC0C5DC,
+	0x01F8FCB784FE9E69, 0x43081D5C2D14A8FA,
+	0xCD2A5925D9681F90, 0x8FDAB8CE70822903,
+	0x48CB9AF28ABC72B6, 0x0A3B7B1923564425,
+	0x70428B155B4EAF1E, 0x32B26AFEF2A4998D,
+	0xF5A348C2089AC238, 0xB753A929A170F4AB,
+	0x3971ED50550C43C1, 0x7B810CBBFCE67552,
+	0xBC902E8706D82EE7, 0xFE60CF6CAF321874,
+	0xE224479F47CB76A0, 0xA0D4A674EE214033,
+	0x67C58448141F1B86, 0x253565A3BDF52D15,
+	0xAB1721DA49899A7F, 0xE9E7C031E063ACEC,
+	0x2EF6E20D1A5DF759, 0x6C0603E6B3B7C1CA,
+	0xF6FAE5C07D3274CD, 0xB40A042BD4D8425E,
+	0x731B26172EE619EB, 0x31EBC7FC870C2F78,
+	0xBFC9838573709812, 0xFD39626EDA9AAE81,
+	0x3A28405220A4F534, 0x78D8A1B9894EC3A7,
+	0x649C294A61B7AD73, 0x266CC8A1C85D9BE0,
+	0xE17DEA9D3263C055, 0xA38D0B769B89F6C6,
+	0x2DAF4F0F6FF541AC, 0x6F5FAEE4C61F773F,
+	0xA84E8CD83C212C8A, 0xEABE6D3395CB1A19,
+	0x90C79D3FEDD3F122, 0xD2377CD44439C7B1,
+	0x15265EE8BE079C04, 0x57D6BF0317EDAA97,
+	0xD9F4FB7AE3911DFD, 0x9B041A914A7B2B6E,
+	0x5C1538ADB04570DB, 0x1EE5D94619AF4648,
+	0x02A151B5F156289C, 0x4051B05E58BC1E0F,
+	0x87409262A28245BA, 0xC5B073890B687329,
+	0x4B9237F0FF14C443, 0x0962D61B56FEF2D0,
+	0xCE73F427ACC0A965, 0x8C8315CC052A9FF6,
+	0x3A80143F5CF17F13, 0x7870F5D4F51B4980,
+	0xBF61D7E80F251235, 0xFD913603A6CF24A6,
+	0x73B3727A52B393CC, 0x31439391FB59A55F,
+	0xF652B1AD0167FEEA, 0xB4A25046A88DC879,
+	0xA8E6D8B54074A6AD, 0xEA16395EE99E903E,
+	0x2D071B6213A0CB8B, 0x6FF7FA89BA4AFD18,
+	0xE1D5BEF04E364A72, 0xA3255F1BE7DC7CE1,
+	0x64347D271DE22754, 0x26C49CCCB40811C7,
+	0x5CBD6CC0CC10FAFC, 0x1E4D8D2B65FACC6F,
+	0xD95CAF179FC497DA, 0x9BAC4EFC362EA149,
+	0x158E0A85C2521623, 0x577EEB6E6BB820B0,
+	0x906FC95291867B05, 0xD29F28B9386C4D96,
+	0xCEDBA04AD0952342, 0x8C2B41A1797F15D1,
+	0x4B3A639D83414E64, 0x09CA82762AAB78F7,
+	0x87E8C60FDED7CF9D, 0xC51827E4773DF90E,
+	0x020905D88D03A2BB, 0x40F9E43324E99428,
+	0x2CFFE7D5975E55E2, 0x6E0F063E3EB46371,
+	0xA91E2402C48A38C4, 0xEBEEC5E96D600E57,
+	0x65CC8190991CB93D, 0x273C607B30F68FAE,
+	0xE02D4247CAC8D41B, 0xA2DDA3AC6322E288,
+	0xBE992B5F8BDB8C5C, 0xFC69CAB42231BACF,
+	0x3B78E888D80FE17A, 0x7988096371E5D7E9,
+	0xF7AA4D1A85996083, 0xB55AACF12C735610,
+	0x724B8ECDD64D0DA5, 0x30BB6F267FA73B36,
+	0x4AC29F2A07BFD00D, 0x08327EC1AE55E69E,
+	0xCF235CFD546BBD2B, 0x8DD3BD16FD818BB8,
+	0x03F1F96F09FD3CD2, 0x41011884A0170A41,
+	0x86103AB85A2951F4, 0xC4E0DB53F3C36767,
+	0xD8A453A01B3A09B3, 0x9A54B24BB2D03F20,
+	0x5D45907748EE6495, 0x1FB5719CE1045206,
+	0x919735E51578E56C, 0xD367D40EBC92D3FF,
+	0x1476F63246AC884A, 0x568617D9EF46BED9,
+	0xE085162AB69D5E3C, 0xA275F7C11F7768AF,
+	0x6564D5FDE549331A, 0x279434164CA30589,
+	0xA9B6706FB8DFB2E3, 0xEB46918411358470,
+	0x2C57B3B8EB0BDFC5, 0x6EA7525342E1E956,
+	0x72E3DAA0AA188782, 0x30133B4B03F2B111,
+	0xF7021977F9CCEAA4, 0xB5F2F89C5026DC37,
+	0x3BD0BCE5A45A6B5D, 0x79205D0E0DB05DCE,
+	0xBE317F32F78E067B, 0xFCC19ED95E6430E8,
+	0x86B86ED5267CDBD3, 0xC4488F3E8F96ED40,
+	0x0359AD0275A8B6F5, 0x41A94CE9DC428066,
+	0xCF8B0890283E370C, 0x8D7BE97B81D4019F,
+	0x4A6ACB477BEA5A2A, 0x089A2AACD2006CB9,
+	0x14DEA25F3AF9026D, 0x562E43B4931334FE,
+	0x913F6188692D6F4B, 0xD3CF8063C0C759D8,
+	0x5DEDC41A34BBEEB2, 0x1F1D25F19D51D821,
+	0xD80C07CD676F8394, 0x9AFCE626CE85B507
+};
+
+#endif /* INT64_IS_BUSTED */
--- 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 1.53 2001/01/24 19:43:16 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/globals.c,v 1.54 2001/03/13 01:17:06 tgl Exp $
 *
 * NOTES
 *	  Globals used all over the place should be declared here and not
@@ -16,14 +16,14 @@
 *
 *-------------------------------------------------------------------------
 */
+#include "postgres.h"
+
 #include <fcntl.h>
 #include <sys/file.h>
 #include <sys/types.h>
 #include <math.h>
 #include <unistd.h>

-#include "postgres.h"
-
 #include "catalog/catname.h"
 #include "catalog/indexing.h"
 #include "libpq/pqcomm.h"
@@ -119,49 +119,3 @@ char	   *SharedSystemRelationNames[] = {
 	VariableRelationName,
 	0
 };
-
-uint32	crc_table[] = {
-0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
-0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
-0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
-0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
-0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
-0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
-0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
-0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
-0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
-0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
-0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
-0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
-0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
-0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
-0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
-0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
-0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
-0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
-0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
-0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
-0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
-0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
-0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
-0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
-0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
-0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
-0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
-0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
-0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
-0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
-0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
-0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
-0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
-0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
-0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
-0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
-0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
-0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
-0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
-0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
-0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
-0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
-0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
-};
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -8,7 +8,7 @@
 *
 *
 * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.61 2001/01/27 00:05:31 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.62 2001/03/13 01:17:06 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
@@ -41,7 +41,8 @@ unsigned char RecodeBackTable[128];

 ProcessingMode Mode = InitProcessing;

-/* Note: we rely on this to initialize as zeroes */
+/* Note: we rely on these to initialize as zeroes */
+static char directoryLockFile[MAXPGPATH];
 static char socketLockFile[MAXPGPATH];


@@ -458,6 +459,9 @@ GetUserName(Oid userid)
 * The path is also just for informational purposes (so that a socket lockfile
 * can be more easily traced to the associated postmaster).
 *
+ * A data-directory lockfile can optionally contain a third line, containing
+ * the key and ID for the shared memory block used by this postmaster.
+ *
 * On successful lockfile creation, a proc_exit callback to remove the
 * lockfile is automatically created.
 *-------------------------------------------------------------------------
@@ -476,16 +480,18 @@ UnlinkLockFile(int status, Datum filename)
 /*
 * Create a lockfile, if possible
 *
- * Call CreateLockFile with the name of the lockfile to be created.  If
- * successful, it returns zero.  On detecting a collision, it returns
- * the PID or negated PID of the lockfile owner --- the caller is responsible
- * for producing an appropriate error message.
+ * Call CreateLockFile with the name of the lockfile to be created.
+ * Returns true if successful, false if not (with a message on stderr).
+ *
+ * amPostmaster is used to determine how to encode the output PID.
+ * isDDLock and refName are used to determine what error message to produce.
 */
-static int
-CreateLockFile(const char *filename, bool amPostmaster)
+static bool
+CreateLockFile(const char *filename, bool amPostmaster,
+			   bool isDDLock, const char *refName)
 {
 	int			fd;
-	char		buffer[MAXPGPATH + 32];
+	char		buffer[MAXPGPATH + 100];
 	int			len;
 	int			encoded_pid;
 	pid_t		other_pid;
@@ -539,11 +545,61 @@ CreateLockFile(const char *filename, bool amPostmaster)
 		{
 			if (kill(other_pid, 0) == 0 ||
 				errno != ESRCH)
-				return encoded_pid;	/* lockfile belongs to a live process */
+			{
+				/* lockfile belongs to a live process */
+				fprintf(stderr, "Lock file \"%s\" already exists.\n",
+						filename);
+				if (isDDLock)
+					fprintf(stderr,
+							"Is another %s (pid %d) running in \"%s\"?\n",
+							(encoded_pid < 0 ? "postgres" : "postmaster"),
+							other_pid, refName);
+				else
+					fprintf(stderr,
+							"Is another %s (pid %d) using \"%s\"?\n",
+							(encoded_pid < 0 ? "postgres" : "postmaster"),
+							other_pid, refName);
+				return false;
+			}
 		}

 		/*
-		 * No, the process did not exist. Unlink the file and try again to
+		 * No, the creating process did not exist.  However, it could be that
+		 * the postmaster crashed (or more likely was kill -9'd by a clueless
+		 * admin) but has left orphan backends behind.  Check for this by
+		 * looking to see if there is an associated shmem segment that is
+		 * still in use.
+		 */
+		if (isDDLock)
+		{
+			char	   *ptr;
+			unsigned long shmKey,
+						shmId;
+
+			ptr = strchr(buffer, '\n');
+			if (ptr != NULL &&
+				(ptr = strchr(ptr+1, '\n')) != NULL)
+			{
+				ptr++;
+				if (sscanf(ptr, "%lu %lu", &shmKey, &shmId) == 2)
+				{
+					if (SharedMemoryIsInUse((IpcMemoryKey) shmKey,
+											(IpcMemoryId) shmId))
+					{
+						fprintf(stderr,
+								"Found a pre-existing shared memory block (ID %d) still in use.\n"
+								"If you're sure there are no old backends still running,\n"
+								"remove the shared memory block with ipcrm(1), or just\n"
+								"delete \"%s\".\n",
+								(int) shmId, filename);
+						return false;
+					}
+				}
+			}
+		}
+
+		/*
+		 * Looks like nobody's home.  Unlink the file and try again to
 		 * create it.  Need a loop because of possible race condition against
 		 * other would-be creators.
 		 */
@@ -576,28 +632,19 @@ CreateLockFile(const char *filename, bool amPostmaster)
 	 */
 	on_proc_exit(UnlinkLockFile, PointerGetDatum(strdup(filename)));

-	return 0;					/* Success! */
+	return true;				/* Success! */
 }

 bool
 CreateDataDirLockFile(const char *datadir, bool amPostmaster)
 {
 	char	lockfile[MAXPGPATH];
-	int		encoded_pid;

 	snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", datadir);
-	encoded_pid = CreateLockFile(lockfile, amPostmaster);
-	if (encoded_pid != 0)
-	{
-		fprintf(stderr, "Lock file \"%s\" already exists.\n", lockfile);
-		if (encoded_pid < 0)
-			fprintf(stderr, "Is another postgres (pid %d) running in \"%s\"?\n",
-					-encoded_pid, datadir);
-		else
-			fprintf(stderr, "Is another postmaster (pid %d) running in \"%s\"?\n",
-					encoded_pid, datadir);
+	if (! CreateLockFile(lockfile, amPostmaster, true, datadir))
 		return false;
-	}
+	/* Save name of lockfile for RecordSharedMemoryInLockFile */
+	strcpy(directoryLockFile, lockfile);
 	return true;
 }

@@ -605,21 +652,10 @@ bool
 CreateSocketLockFile(const char *socketfile, bool amPostmaster)
 {
 	char	lockfile[MAXPGPATH];
-	int		encoded_pid;

 	snprintf(lockfile, sizeof(lockfile), "%s.lock", socketfile);
-	encoded_pid = CreateLockFile(lockfile, amPostmaster);
-	if (encoded_pid != 0)
-	{
-		fprintf(stderr, "Lock file \"%s\" already exists.\n", lockfile);
-		if (encoded_pid < 0)
-			fprintf(stderr, "Is another postgres (pid %d) using \"%s\"?\n",
-					-encoded_pid, socketfile);
-		else
-			fprintf(stderr, "Is another postmaster (pid %d) using \"%s\"?\n",
-					encoded_pid, socketfile);
+	if (! CreateLockFile(lockfile, amPostmaster, false, socketfile))
 		return false;
-	}
 	/* Save name of lockfile for TouchSocketLockFile */
 	strcpy(socketLockFile, lockfile);
 	return true;
@@ -650,6 +686,78 @@ TouchSocketLockFile(void)
 	}
 }

+/*
+ * Append information about a shared memory segment to the data directory
+ * lock file (if we have created one).
+ *
+ * This may be called multiple times in the life of a postmaster, if we
+ * delete and recreate shmem due to backend crash.  Therefore, be prepared
+ * to overwrite existing information.  (As of 7.1, a postmaster only creates
+ * one shm seg anyway; but for the purposes here, if we did have more than
+ * one then any one of them would do anyway.)
+ */
+void
+RecordSharedMemoryInLockFile(IpcMemoryKey shmKey, IpcMemoryId shmId)
+{
+	int			fd;
+	int			len;
+	char	   *ptr;
+	char		buffer[BLCKSZ];
+
+	/*
+	 * Do nothing if we did not create a lockfile (probably because we
+	 * are running standalone).
+	 */
+	if (directoryLockFile[0] == '\0')
+		return;
+
+	fd = open(directoryLockFile, O_RDWR | PG_BINARY, 0);
+	if (fd < 0)
+	{
+		elog(DEBUG, "Failed to rewrite %s: %m", directoryLockFile);
+		return;
+	}
+	len = read(fd, buffer, sizeof(buffer) - 100);
+	if (len <= 0)
+	{
+		elog(DEBUG, "Failed to read %s: %m", directoryLockFile);
+		close(fd);
+		return;
+	}
+	buffer[len] = '\0';
+	/*
+	 * Skip over first two lines (PID and path).
+	 */
+	ptr = strchr(buffer, '\n');
+	if (ptr == NULL ||
+		(ptr = strchr(ptr+1, '\n')) == NULL)
+	{
+		elog(DEBUG, "Bogus data in %s", directoryLockFile);
+		close(fd);
+		return;
+	}
+	ptr++;
+	/*
+	 * Append shm key and ID.  Format to try to keep it the same length
+	 * always (trailing junk won't hurt, but might confuse humans).
+	 */
+	sprintf(ptr, "%9lu %9lu\n",
+			(unsigned long) shmKey, (unsigned long) shmId);
+	/*
+	 * And rewrite the data.  Since we write in a single kernel call,
+	 * this update should appear atomic to onlookers.
+	 */
+	len = strlen(buffer);
+	if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
+		(int) write(fd, buffer, len) != len)
+	{
+		elog(DEBUG, "Failed to write %s: %m", directoryLockFile);
+		close(fd);
+		return;
+	}
+	close(fd);
+}
+

 /*-------------------------------------------------------------------------
 *				Version checking support
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -4,7 +4,7 @@
 * Support for grand unified configuration scheme, including SET
 * command, configuration file, and command line options.
 *
- * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.31 2001/02/26 00:50:07 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/utils/misc/guc.c,v 1.32 2001/03/13 01:17:06 tgl Exp $
 *
 * Copyright 2000 by PostgreSQL Global Development Group
 * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -36,6 +36,7 @@
 /* XXX should be in a header file */
 extern bool Log_connections;

+extern int CheckPointSegments;
 extern int CheckPointTimeout;
 extern int XLOGbuffers;
 extern int XLOGfiles;
@@ -279,13 +280,16 @@ ConfigureNamesInt[] =
 	{"unix_socket_permissions", PGC_POSTMASTER,         &Unix_socket_permissions,
 	 0777, 0000, 0777},

-	{"checkpoint_timeout",	PGC_POSTMASTER,			&CheckPointTimeout,
+	{"checkpoint_segments",	PGC_SIGHUP,				&CheckPointSegments,
+	 3, 1, INT_MAX},
+
+	{"checkpoint_timeout",	PGC_SIGHUP,				&CheckPointTimeout,
 	 300, 30, 3600},

 	{"wal_buffers",			PGC_POSTMASTER,			&XLOGbuffers,
 	 8, 4, INT_MAX},

-	{"wal_files",			PGC_POSTMASTER,			&XLOGfiles,
+	{"wal_files",			PGC_SIGHUP,				&XLOGfiles,
 	 0, 0, 64},

 	{"wal_debug",			PGC_SUSET,				&XLOG_DEBUG,
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -110,6 +110,7 @@
 #wal_debug = 0 # range 0-16
 #commit_delay = 0 # range 0-100000
 #commit_siblings = 5 # range 1-1000
+#checkpoint_segments = 3 # in logfile segments (16MB each), min 1
 #checkpoint_timeout = 300 # in seconds, range 30-3600