Arrange for the postmaster (and standalone backends, initdb, etc) to

chdir into PGDATA and subsequently use relative paths instead of absolute
paths to access all files under PGDATA.  This seems to give a small
performance improvement, and it should make the system more robust
against naive DBAs doing things like moving a database directory that
has a live postmaster in it.  Per recent discussion.

1 files changed, 12 insertions, 45 deletions

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 86b873ab36b..325bb8b451a 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -13,7 +13,7 @@
  *
  *	Copyright (c) 2001-2005, PostgreSQL Global Development Group
  *
- *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.98 2005/06/29 22:51:55 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.99 2005/07/04 04:51:47 tgl Exp $
  * ----------
  */
 #include "postgres.h"
@@ -54,12 +54,11 @@
 
 
 /* ----------
- * Paths for the statistics files. The %s is replaced with the
- * installation's $PGDATA.
+ * Paths for the statistics files (relative to installation's $PGDATA).
  * ----------
  */
-#define PGSTAT_STAT_FILENAME	"%s/global/pgstat.stat"
-#define PGSTAT_STAT_TMPFILE		"%s/global/pgstat.tmp.%d"
+#define PGSTAT_STAT_FILENAME	"global/pgstat.stat"
+#define PGSTAT_STAT_TMPFILE		"global/pgstat.tmp"
 
 /* ----------
  * Timer definitions.
@@ -134,9 +133,6 @@ static HTAB *pgStatBeDead = NULL;
 static PgStat_StatBeEntry *pgStatBeTable = NULL;
 static int	pgStatNumBackends = 0;
 
-static char pgStat_fname[MAXPGPATH];
-static char pgStat_tmpfname[MAXPGPATH];
-
 
 /* ----------
  * Local function forward declarations
@@ -221,20 +217,11 @@ pgstat_init(void)
 		pgstat_collect_startcollector = true;
 
 	/*
-	 * Initialize the filename for the status reports.	(In the
-	 * EXEC_BACKEND case, this only sets the value in the postmaster.  The
-	 * collector subprocess will recompute the value for itself, and
-	 * individual backends must do so also if they want to access the
-	 * file.)
-	 */
-	snprintf(pgStat_fname, MAXPGPATH, PGSTAT_STAT_FILENAME, DataDir);
-
-	/*
 	 * If we don't have to start a collector or should reset the collected
-	 * statistics on postmaster start, simply remove the file.
+	 * statistics on postmaster start, simply remove the stats file.
 	 */
 	if (!pgstat_collect_startcollector || pgstat_collect_resetonpmstart)
-		unlink(pgStat_fname);
+		unlink(PGSTAT_STAT_FILENAME);
 
 	/*
 	 * Nothing else required if collector will not get started
@@ -1471,14 +1458,6 @@ PgstatCollectorMain(int argc, char *argv[])
 	set_ps_display("");
 
 	/*
-	 * Initialize filenames needed for status reports.
-	 */
-	snprintf(pgStat_fname, MAXPGPATH, PGSTAT_STAT_FILENAME, DataDir);
-	/* tmpfname need only be set correctly in this process */
-	snprintf(pgStat_tmpfname, MAXPGPATH, PGSTAT_STAT_TMPFILE,
-			 DataDir, (int)getpid());
-
-	/*
 	 * Arrange to write the initial status file right away
 	 */
 	gettimeofday(&next_statwrite, NULL);
@@ -2161,13 +2140,13 @@ pgstat_write_statsfile(void)
 	/*
 	 * Open the statistics temp file to write out the current values.
 	 */
-	fpout = fopen(pgStat_tmpfname, PG_BINARY_W);
+	fpout = fopen(PGSTAT_STAT_TMPFILE, PG_BINARY_W);
 	if (fpout == NULL)
 	{
 		ereport(LOG,
 				(errcode_for_file_access(),
 			errmsg("could not open temporary statistics file \"%s\": %m",
-				   pgStat_tmpfname)));
+				   PGSTAT_STAT_TMPFILE)));
 		return;
 	}
 
@@ -2276,16 +2255,16 @@ pgstat_write_statsfile(void)
 		ereport(LOG,
 				(errcode_for_file_access(),
 		   errmsg("could not close temporary statistics file \"%s\": %m",
-				  pgStat_tmpfname)));
+				  PGSTAT_STAT_TMPFILE)));
 	}
 	else
 	{
-		if (rename(pgStat_tmpfname, pgStat_fname) < 0)
+		if (rename(PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME) < 0)
 		{
 			ereport(LOG,
 					(errcode_for_file_access(),
 					 errmsg("could not rename temporary statistics file \"%s\" to \"%s\": %m",
-							pgStat_tmpfname, pgStat_fname)));
+							PGSTAT_STAT_TMPFILE, PGSTAT_STAT_FILENAME)));
 		}
 	}
 
@@ -2377,23 +2356,11 @@ pgstat_read_statsfile(HTAB **dbhash, Oid onlydb,
 		*betab = NULL;
 
 	/*
-	 * In EXEC_BACKEND case, we won't have inherited pgStat_fname from
-	 * postmaster, so compute it first time through.
-	 */
-#ifdef EXEC_BACKEND
-	if (pgStat_fname[0] == '\0')
-	{
-		Assert(DataDir != NULL);
-		snprintf(pgStat_fname, MAXPGPATH, PGSTAT_STAT_FILENAME, DataDir);
-	}
-#endif
-
-	/*
 	 * Try to open the status file. If it doesn't exist, the backends
 	 * simply return zero for anything and the collector simply starts
 	 * from scratch with empty counters.
 	 */
-	if ((fpin = AllocateFile(pgStat_fname, PG_BINARY_R)) == NULL)
+	if ((fpin = AllocateFile(PGSTAT_STAT_FILENAME, PG_BINARY_R)) == NULL)
 		return;
 
 	/*