v25-0005-Remove-the-GUC-stats_temp_directory.patch

From b312af2688f8e32506909298ea76d1a96785025f Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@gmail.com>
Date: Thu, 19 Mar 2020 14:38:10 +1300
Subject: [PATCH v25 5/5] Remove the GUC stats_temp_directory.

---
 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 70854ae298..404d4d5e19 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -7109,25 +7109,6 @@ 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 3ffec474cf..6f58f2b94b 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 61a64fefba..c641de3378 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -110,15 +110,12 @@ 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 806d013108..c086ab781b 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -251,15 +251,12 @@ perform_base_backup(basebackup_options *opt)
 	TimeLineID	endtli;
 	StringInfo	labelfile;
 	StringInfo	tblspc_map_file = NULL;
-	int			datadirpathlen;
 	List	   *tablespaces = NIL;
 
 	backup_total = 0;
 	backup_streamed = 0;
 	pgstat_progress_start_command(PROGRESS_COMMAND_BASEBACKUP, InvalidOid);
 
-	datadirpathlen = strlen(DataDir);
-
 	backup_started_in_recovery = RecoveryInProgress();
 
 	labelfile = makeStringInfo();
@@ -291,13 +288,9 @@ 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 af876d1f01..cabeb806c5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -197,7 +197,6 @@ 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 bool check_maintenance_io_concurrency(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);
@@ -4231,17 +4230,6 @@ 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."),
@@ -11518,35 +11506,6 @@ check_maintenance_io_concurrency(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 aa44f0c9bf..207e042e99 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -573,7 +573,6 @@
 #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 430ff65026..5cbb5789b4 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 9575268bd7..f3340f726c 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")
-- 
2.20.1