Make the 'wal_debug' GUC variable a boolean (rather than an integer), and

hide it behind #ifdef WAL_DEBUG blocks.

doc/src/sgml/ref/show.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/show.sgml,v 1.34 2003/11/29 19:51:39 pgsql Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/show.sgml,v 1.35 2004/01/06 17:26:23 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -172,7 +172,7 @@ SHOW ALL;
     .
     .
     .
- wal_debug                     | 0
+ wal_debug                     | off
  wal_sync_method               | fdatasync
 (94 rows)
 </programlisting>

doc/src/sgml/runtime.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.228 2004/01/05 20:37:51 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.229 2004/01/06 17:26:22 neilc Exp $
 -->
 
 <Chapter Id="runtime">
@@ -2667,10 +2667,13 @@ dynamic_library_path = '/usr/local/lib/postgresql:/home/my_project/lib:$libdir'
      </varlistentry>
 
      <varlistentry>
-      <term><varname>wal_debug</varname> (<type>integer</type>)</term>
+      <term><varname>wal_debug</varname> (<type>boolean</type>)</term>
       <listitem>
        <para>
-        If nonzero, turn on WAL-related debugging output.
+        If true, emit WAL-related debugging output. This option is
+        only available if the <symbol>WAL_DEBUG</symbol> macro was
+        defined when <productname>PostgreSQL</productname> was
+        compiled.
        </para>
       </listitem>
      </varlistentry>

doc/src/sgml/wal.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.26 2003/11/29 19:51:38 pgsql Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/wal.sgml,v 1.27 2004/01/06 17:26:23 neilc Exp $ -->
 
 <chapter id="wal">
  <title>Write-Ahead Logging (<acronym>WAL</acronym>)</title>
@@ -19,10 +19,10 @@
    transaction processing. Briefly, <acronym>WAL</acronym>'s central
    concept is that changes to data files (where tables and indexes
    reside) must be written only after those changes have been logged,
-   that is, when log records have been flushed to permanent
-   storage. If we follow this procedure, we do not need to flush
-   data pages to disk on every transaction commit, because we know
-   that in the event of a crash we will be able to recover the
+   that is, when log records describing the changes have been flushed
+   to permanent storage. If we follow this procedure, we do not need
+   to flush data pages to disk on every transaction commit, because we
+   know that in the event of a crash we will be able to recover the
    database using the log: any changes that have not been applied to
    the data pages will first be redone from the log records (this is
    roll-forward recovery, also known as REDO) and then changes made by
@@ -187,7 +187,7 @@
   <para>
    There will be at least one 16 MB segment file, and will normally
    not be more than 2 * <varname>checkpoint_segments</varname> + 1
-   files.  You can use this to estimate space requirements for WAL.
+   files.  You can use this to estimate space requirements for <acronym>WAL</acronym>.
    Ordinarily, when old log segment files are no longer needed, they
    are recycled (renamed to become the next segments in the numbered
    sequence). If, due to a short-term peak of log output rate, there
@@ -254,7 +254,7 @@
   <para>
    The <varname>wal_sync_method</varname> parameter determines how
    <productname>PostgreSQL</productname> will ask the kernel to force
-    WAL updates out to disk. 
+    <acronym>WAL</acronym> updates out to disk. 
    All the options should be the same as far as reliability goes,
    but it's quite platform-specific which one will be the fastest.
    Note that this parameter is irrelevant if <varname>fsync</varname>
@@ -262,11 +262,10 @@
   </para>
 
   <para>
-   Setting the <varname>wal_debug</varname> parameter to any nonzero
-   value will result in each <function>LogInsert</function> and
+   Enabling the <varname>wal_debug</varname> configuration parameter
+   will result in each <function>LogInsert</function> and
    <function>LogFlush</function> <acronym>WAL</acronym> call being
-   logged to the server log.  At present, it makes no difference what
-   the nonzero value is.  This option may be replaced by a more
+   logged to the server log. This option may be replaced by a more
    general mechanism in the future.
   </para>
  </sect1>

src/backend/access/transam/xlog.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.129 2003/12/20 17:31:20 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.130 2004/01/06 17:26:23 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,12 +86,15 @@
 /* User-settable parameters */
 int			CheckPointSegments = 3;
 int			XLOGbuffers = 8;
-int			XLOG_DEBUG = 0;
 char	   *XLOG_sync_method = NULL;
 const char	XLOG_sync_method_default[] = DEFAULT_SYNC_METHOD_STR;
 char		XLOG_archive_dir[MAXPGPATH];		/* null string means
 												 * delete 'em */
 
+#ifdef WAL_DEBUG
+bool		XLOG_DEBUG = false;
+#endif
+
 /*
  * XLOGfileslop is used in the code as the allowed "fuzz" in the number of
  * preallocated XLOG segments --- we try to have at least XLOGfiles advance
@@ -766,6 +769,7 @@ begin:;
 		MyProc->logRec = RecPtr;
 	}
 
+#ifdef WAL_DEBUG
 	if (XLOG_DEBUG)
 	{
 		char		buf[8192];
@@ -779,6 +783,7 @@ begin:;
 		}
 		elog(LOG, "%s", buf);
 	}
+#endif
 
 	/* Record begin of record in appropriate places */
 	if (!no_tran)
@@ -1074,8 +1079,10 @@ XLogWrite(XLogwrtRqst WriteRqst)
 					 openLogSeg >= (RedoRecPtr.xrecoff / XLogSegSize) +
 					 (uint32) CheckPointSegments))
 				{
+#ifdef WAL_DEBUG
 					if (XLOG_DEBUG)
 						elog(LOG, "time for a checkpoint, signaling postmaster");
+#endif
 					SendPostmasterSignal(PMSIGNAL_DO_CHECKPOINT);
 				}
 			}
@@ -1214,11 +1221,13 @@ XLogFlush(XLogRecPtr record)
 	if (XLByteLE(record, LogwrtResult.Flush))
 		return;
 
+#ifdef WAL_DEBUG
 	if (XLOG_DEBUG)
 		elog(LOG, "xlog flush request %X/%X; write %X/%X; flush %X/%X",
 			 record.xlogid, record.xrecoff,
 			 LogwrtResult.Write.xlogid, LogwrtResult.Write.xrecoff,
 			 LogwrtResult.Flush.xlogid, LogwrtResult.Flush.xrecoff);
+#endif
 
 	START_CRIT_SECTION();
 
@@ -2613,8 +2622,10 @@ StartupXLOG(void)
 
 	/* This is just to allow attaching to startup process with a debugger */
 #ifdef XLOG_REPLAY_DELAY
+#ifdef WAL_DEBUG
 	if (XLOG_DEBUG && ControlFile->state != DB_SHUTDOWNED)
 		sleep(60);
+#endif
 #endif
 
 	/*
@@ -2742,6 +2753,8 @@ StartupXLOG(void)
 					ShmemVariableCache->nextXid = record->xl_xid;
 					TransactionIdAdvance(ShmemVariableCache->nextXid);
 				}
+
+#ifdef WAL_DEBUG
 				if (XLOG_DEBUG)
 				{
 					char		buf[8192];
@@ -2755,6 +2768,7 @@ StartupXLOG(void)
 								record->xl_info, XLogRecGetData(record));
 					elog(LOG, "%s", buf);
 				}
+#endif
 
 				if (record->xl_info & XLR_BKP_BLOCK_MASK)
 					RestoreBkpBlocks(record, EndRecPtr);

src/backend/utils/misc/guc.c

@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.175 2003/12/03 18:52:00 joe Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.176 2004/01/06 17:26:23 neilc Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -336,17 +336,18 @@ const char *const config_type_names[] =
  * TO ADD AN OPTION:
  *
  * 1. Declare a global variable of type bool, int, double, or char*
- * and make use of it.
+ *    and make use of it.
  *
  * 2. Decide at what times it's safe to set the option. See guc.h for
- * details.
+ *    details.
  *
  * 3. Decide on a name, a default value, upper and lower bounds (if
- * applicable), etc.
+ *    applicable), etc.
  *
  * 4. Add a record below.
  *
- * 5. Add it to src/backend/utils/misc/postgresql.conf.sample.
+ * 5. Add it to src/backend/utils/misc/postgresql.conf.sample, if
+ *    appropriate
  *
  * 6. Add it to src/bin/psql/tab-complete.c, if it's a USERSET option.
  *
@@ -862,6 +863,18 @@ static struct config_bool ConfigureNamesBool[] =
 #endif
 	},
 
+#ifdef WAL_DEBUG
+	{
+		{"wal_debug", PGC_SUSET, DEVELOPER_OPTIONS,
+			gettext_noop("Emit WAL-related debugging output."),
+			NULL,
+			GUC_NOT_IN_SAMPLE
+		},
+		&XLOG_DEBUG,
+		false, NULL, NULL
+	},
+#endif
+
 	/* End-of-list marker */
 	{
 		{NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL
@@ -1171,16 +1184,6 @@ static struct config_int ConfigureNamesInt[] =
 		8, 4, INT_MAX, NULL, NULL
 	},
 
-	{
-		{"wal_debug", PGC_SUSET, DEVELOPER_OPTIONS,
-			gettext_noop("If nonzero, WAL-related debugging output is logged."),
-			NULL,
-			GUC_NOT_IN_SAMPLE
-		},
-		&XLOG_DEBUG,
-		0, 0, 16, NULL, NULL
-	},
-
 	{
 		{"commit_delay", PGC_USERSET, WAL_CHECKPOINTS,
 			gettext_noop("Sets the delay in microseconds between transaction commit and "

src/include/access/xlog.h

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.46 2003/12/12 18:45:10 petere Exp $
+ * $PostgreSQL: pgsql/src/include/access/xlog.h,v 1.47 2004/01/06 17:26:23 neilc Exp $
  */
 #ifndef XLOG_H
 #define XLOG_H
@@ -189,10 +189,12 @@ extern XLogRecPtr ProcLastRecEnd;
 extern int	CheckPointSegments;
 extern int	CheckPointWarning;
 extern int	XLOGbuffers;
-extern int	XLOG_DEBUG;
 extern char *XLOG_sync_method;
 extern const char XLOG_sync_method_default[];
 
+#ifdef WAL_DEBUG
+extern bool	XLOG_DEBUG;
+#endif
 
 extern XLogRecPtr XLogInsert(RmgrId rmid, uint8 info, XLogRecData *rdata);
 extern void XLogFlush(XLogRecPtr RecPtr);

src/include/pg_config_manual.h

@@ -6,7 +6,7 @@
  * for developers.	If you edit any of these, be sure to do a *full*
  * rebuild (and an initdb if noted).
  *
- * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.8 2003/11/29 22:40:53 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.9 2004/01/06 17:26:23 neilc Exp $
  *------------------------------------------------------------------------
  */
 
@@ -224,6 +224,12 @@
  */
 /* #define LOCK_DEBUG */
 
+/*
+ * Enable debugging print statements for WAL-related operations; see
+ * also the wal_debug GUC var.
+ */
+/* #define WAL_DEBUG */
+
 /*
  * Other debug #defines (documentation, anyone?)
  */