Subject: [PATCH v22 5/5] Remove the GUC stats_temp_directory

From: Kyotaro Horiguchi <[email-masked]>
Date: Tue, 27 Nov 2018 14:42:12 +0900

The guc used to specifie 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 contirb, and maybe other extensions. Thus this
patch removes the GUC but some backing variables and macro definitions
are left alone for backward comptibility.
---
 doc/src/sgml/backup.sgml                      |  2 --
 doc/src/sgml/config.sgml                      | 19 -------------
 doc/src/sgml/monitoring.sgml                  |  7 +----
 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 ---
 10 files changed, 14 insertions(+), 94 deletions(-)

diff --git a/doc/src/sgml/backup.sgml b/doc/src/sgml/backup.sgml
index bdc9026c62..2885540362 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 7f9ce8fcba..a8bed31232 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -6818,25 +6818,6 @@ 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/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index ea6aad4d1e..33ad2b8be8 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -195,12 +195,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
 
   <para>
    The statistics collector transmits the collected information to other
-   <productname>PostgreSQL</productname> processes through temporary files.
-   These files are stored in the directory named by the
-   <xref linkend="guc-stats-temp-directory"/> parameter,
-   <filename>pg_stat_tmp</filename> by default.
-   For better performance, <varname>stats_temp_directory</varname> can be
-   pointed at a RAM-based file system, decreasing physical I/O requirements.
+   <productname>PostgreSQL</productname> processes through shared memory.
    When the server shuts down cleanly, a permanent copy of the statistics
    data is stored in the <filename>pg_stat</filename> subdirectory, so that
    statistics can be retained across server restarts.  When recovery is
diff --git a/doc/src/sgml/storage.sgml b/doc/src/sgml/storage.sgml
index 1c19e863d2..2f04bb68bb 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 c0b20763b0..6b8025ad13 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -108,15 +108,12 @@ 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 comptibility 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;
 
 #define		StatsLock (&StatsShmem->StatsMainLock)
 
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 6aab8d7b5f..2eb49924b9 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -242,11 +242,8 @@ perform_base_backup(basebackup_options *opt)
 	TimeLineID	endtli;
 	StringInfo	labelfile;
 	StringInfo	tblspc_map_file = NULL;
-	int			datadirpathlen;
 	List	   *tablespaces = NIL;
 
-	datadirpathlen = strlen(DataDir);
-
 	backup_started_in_recovery = RecoveryInProgress();
 
 	labelfile = makeStringInfo();
@@ -277,13 +274,9 @@ 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 90ffd89339..753e30ebb7 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -194,7 +194,6 @@ static bool check_max_wal_senders(int *newval, void **extra, GucSource source);
 static bool check_autovacuum_work_mem(int *newval, void **extra, GucSource source);
 static bool check_effective_io_concurrency(int *newval, void **extra, GucSource source);
 static void assign_effective_io_concurrency(int newval, void *extra);
-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);
@@ -4072,17 +4071,6 @@ static struct config_string ConfigureNamesString[] =
 		NULL, NULL, NULL
 	},
 
-	{
-		{"stats_temp_directory", PGC_SIGHUP, STATS_COLLECTOR,
-			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_MASTER,
 			gettext_noop("Number of synchronous standbys and list of names of potential synchronous ones."),
@@ -11352,35 +11340,6 @@ assign_effective_io_concurrency(int newval, void *extra)
 #endif							/* USE_PREFETCH */
 }
 
-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 0fc23e3a61..66f539c4bb 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -558,7 +558,6 @@
 #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 c9fbcead3f..e9e18ed27a 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -30,7 +30,10 @@
 #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 270bd6c856..c604c5e90b 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")
-- 
2.16.3

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