Subject: [PATCH v37 6/6] Remove the GUC stats_temp_directory

From: Kyotaro Horiguchi <[email-masked]>
Date: Fri, 13 Mar 2020 17:00:44 +0900

The GUC used to specify the directory to store temporary statistics
files. It is no longer needed by the stats collector but still used by
the programs in bin and contrib, and maybe other extensions. Thus this
patch removes the GUC but some backing variables and macro definitions
are left alone for backward compatibility.
---
 doc/src/sgml/backup.sgml                      |  2 -
 doc/src/sgml/config.sgml                      | 19 ---------
 doc/src/sgml/storage.sgml                     |  3 +-
 src/backend/postmaster/pgstat.c               | 13 +++---
 src/backend/replication/basebackup.c          | 13 ++----
 src/backend/utils/misc/guc.c                  | 41 -------------------
 src/backend/utils/misc/postgresql.conf.sample |  1 -
 src/include/pgstat.h                          |  5 ++-
 src/test/perl/PostgresNode.pm                 |  4 --
 9 files changed, 13 insertions(+), 88 deletions(-)

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index b9331830f7..5096963234 100644
--- a/doc/src/sgml/backup.sgml
+++ b/doc/src/sgml/backup.sgml
@@ -1146,8 +1146,6 @@ SELECT pg_stop_backup();
     <filename>pg_snapshots/</filename>, <filename>pg_stat_tmp/</filename>,
     and <filename>pg_subtrans/</filename> (but not the directories themselves) can be
     omitted from the backup as they will be initialized on postmaster startup.
-    If <xref linkend="guc-stats-temp-directory"/> is set and is under the data
-    directory then the contents of that directory can also be omitted.
    </para>
 
    <para>
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index cc5dc1173f..d8d99bb546 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7305,25 +7305,6 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
       </listitem>
      </varlistentry>
 
-     <varlistentry id="guc-stats-temp-directory" xreflabel="stats_temp_directory">
-      <term><varname>stats_temp_directory</varname> (<type>string</type>)
-      <indexterm>
-       <primary><varname>stats_temp_directory</varname> configuration parameter</primary>
-      </indexterm>
-      </term>
-      <listitem>
-       <para>
-        Sets the directory to store temporary statistics data in. This can be
-        a path relative to the data directory or an absolute path. The default
-        is <filename>pg_stat_tmp</filename>. Pointing this at a RAM-based
-        file system will decrease physical I/O requirements and can lead to
-        improved performance.
-        This parameter can only be set in the <filename>postgresql.conf</filename>
-        file or on the server command line.
-       </para>
-      </listitem>
-     </varlistentry>
-
      </variablelist>
     </sect2>
 
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 3234adb639..559f75fb54 100644
--- a/doc/src/sgml/storage.sgml
+++ b/doc/src/sgml/storage.sgml
@@ -122,8 +122,7 @@ Item
 
 <row>
  <entry><filename>pg_stat_tmp</filename></entry>
- <entry>Subdirectory containing temporary files for the statistics
-  subsystem</entry>
+ <entry>Subdirectory containing ephemeral files for extensions</entry>
 </row>
 
 <row>
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 1cd4cb20b6..68b5745bf9 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -98,15 +98,12 @@ bool		pgstat_track_counts = false;
 int			pgstat_track_functions = TRACK_FUNC_OFF;
 int			pgstat_track_activity_query_size = 1024;
 
-/* ----------
- * Built from GUC parameter
- * ----------
+/*
+ * This used to be a GUC variable and is no longer used in this file, but left
+ * alone just for backward compatibility for extensions, having the default
+ * value.
  */
-char	   *pgstat_stat_directory = NULL;
-
-/* No longer used, but will be removed with GUC */
-char	   *pgstat_stat_filename = NULL;
-char	   *pgstat_stat_tmpname = NULL;
+char	   *pgstat_stat_directory = PG_STAT_TMP_DIR;
 
 /*
  * List of SLRU names that we keep stats for.  There is no central registry of
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 57531d7d48..f03720fa48 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -261,7 +261,6 @@ perform_base_backup(basebackup_options *opt)
 	StringInfo	labelfile;
 	StringInfo	tblspc_map_file;
 	backup_manifest_info manifest;
-	int			datadirpathlen;
 	List	   *tablespaces = NIL;
 
 	backup_total = 0;
@@ -284,8 +283,6 @@ perform_base_backup(basebackup_options *opt)
 	Assert(CurrentResourceOwner == NULL);
 	CurrentResourceOwner = ResourceOwnerCreate(NULL, "base backup");
 
-	datadirpathlen = strlen(DataDir);
-
 	backup_started_in_recovery = RecoveryInProgress();
 
 	labelfile = makeStringInfo();
@@ -318,13 +315,9 @@ perform_base_backup(basebackup_options *opt)
 		 * Calculate the relative path of temporary statistics directory in
 		 * order to skip the files which are located in that directory later.
 		 */
-		if (is_absolute_path(pgstat_stat_directory) &&
-			strncmp(pgstat_stat_directory, DataDir, datadirpathlen) == 0)
-			statrelpath = psprintf("./%s", pgstat_stat_directory + datadirpathlen + 1);
-		else if (strncmp(pgstat_stat_directory, "./", 2) != 0)
-			statrelpath = psprintf("./%s", pgstat_stat_directory);
-		else
-			statrelpath = pgstat_stat_directory;
+
+		Assert(strchr(PG_STAT_TMP_DIR, '/') == NULL);
+		statrelpath = psprintf("./%s", PG_STAT_TMP_DIR);
 
 		/* Add a node for the base directory at the end */
 		ti = palloc0(sizeof(tablespaceinfo));
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 29eb459e35..467f9299b3 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -202,7 +202,6 @@ static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource sourc
 static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
 static bool check_maintenance_io_concurrency(int *newval, void **extra, GucSource source);
 static bool check_huge_page_size(int *newval, void **extra, GucSource source);
-static void assign_pgstat_temp_directory(const char *newval, void *extra);
 static bool check_application_name(char **newval, void **extra, GucSource source);
 static void assign_application_name(const char *newval, void *extra);
 static bool check_cluster_name(char **newval, void **extra, GucSource source);
@@ -4309,17 +4308,6 @@ static struct config_string ConfigureNamesString[] =
 		NULL, NULL, NULL
 	},
 
-	{
-		{"stats_temp_directory", PGC_SIGHUP, STATS_ACTIVITY,
-			gettext_noop("Writes temporary statistics files to the specified directory."),
-			NULL,
-			GUC_SUPERUSER_ONLY
-		},
-		&pgstat_temp_directory,
-		PG_STAT_TMP_DIR,
-		check_canonical_path, assign_pgstat_temp_directory, NULL
-	},
-
 	{
 		{"synchronous_standby_names", PGC_SIGHUP, REPLICATION_PRIMARY,
 			gettext_noop("Number of synchronous standbys and list of names of potential synchronous ones."),
@@ -11608,35 +11596,6 @@ check_huge_page_size(int *newval, void **extra, GucSource source)
 	return true;
 }
 
-static void
-assign_pgstat_temp_directory(const char *newval, void *extra)
-{
-	/* check_canonical_path already canonicalized newval for us */
-	char	   *dname;
-	char	   *tname;
-	char	   *fname;
-
-	/* directory */
-	dname = guc_malloc(ERROR, strlen(newval) + 1);	/* runtime dir */
-	sprintf(dname, "%s", newval);
-
-	/* global stats */
-	tname = guc_malloc(ERROR, strlen(newval) + 12); /* /global.tmp */
-	sprintf(tname, "%s/global.tmp", newval);
-	fname = guc_malloc(ERROR, strlen(newval) + 13); /* /global.stat */
-	sprintf(fname, "%s/global.stat", newval);
-
-	if (pgstat_stat_directory)
-		free(pgstat_stat_directory);
-	pgstat_stat_directory = dname;
-	if (pgstat_stat_tmpname)
-		free(pgstat_stat_tmpname);
-	pgstat_stat_tmpname = tname;
-	if (pgstat_stat_filename)
-		free(pgstat_stat_filename);
-	pgstat_stat_filename = fname;
-}
-
 static bool
 check_application_name(char **newval, void **extra, GucSource source)
 {
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 668a2d033a..7183c08305 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -586,7 +586,6 @@
 #track_io_timing = off
 #track_functions = none			# none, pl, all
 #track_activity_query_size = 1024	# (change requires restart)
-#stats_temp_directory = 'pg_stat_tmp'

 # - Monitoring -
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 396ecdb53f..0b41156b3c 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -32,7 +32,10 @@
 #define PGSTAT_STAT_PERMANENT_FILENAME		"pg_stat/global.stat"
 #define PGSTAT_STAT_PERMANENT_TMPFILE		"pg_stat/global.tmp"
 
-/* Default directory to store temporary statistics data in */
+/*
+ * This used to be the directory to store temporary statistics data in but is
+ * no longer used. Defined here for backward compatibility.
+ */
 #define PG_STAT_TMP_DIR		"pg_stat_tmp"
 
 /* Values for track_functions GUC variable --- order is significant! */
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
index 1488bffa2b..bb5474b878 100644
--- a/src/test/perl/PostgresNode.pm
+++ b/src/test/perl/PostgresNode.pm
@@ -455,10 +455,6 @@ sub init
 	print $conf TestLib::slurp_file($ENV{TEMP_CONFIG})
 	  if defined $ENV{TEMP_CONFIG};
 
-	# XXX Neutralize any stats_temp_directory in TEMP_CONFIG.  Nodes running
-	# concurrently must not share a stats_temp_directory.
-	print $conf "stats_temp_directory = 'pg_stat_tmp'\n";
-
 	if ($params{allows_streaming})
 	{
 		if ($params{allows_streaming} eq "logical")
-- 
2.18.4

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