pgstat: remove stats_temp_directory.

With stats now being stored in shared memory, the GUC isn't needed
anymore. However, the pg_stat_tmp directory and PG_STAT_TMP_DIR define are
kept, as pg_stat_statements (and some out-of-core extensions) store data in
it.

Docs will be updated in a subsequent commit, together with the other pending
docs updates due to shared memory stats.

Author: Andres Freund <andres@anarazel.de>
Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20220330233550.eiwsbearu6xhuqwe@alap3.anarazel.de
Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de

contrib/pg_stat_statements/pg_stat_statements.c

@@ -78,12 +78,7 @@ PG_MODULE_MAGIC;
 #define PGSS_DUMP_FILE	PGSTAT_STAT_PERMANENT_DIRECTORY "/pg_stat_statements.stat"
 
 /*
- * Location of external query text file.  We don't keep it in the core
- * system's stats_temp_directory.  The core system can safely use that GUC
- * setting, because the statistics collector temp file paths are set only once
- * as part of changing the GUC, but pg_stat_statements has no way of avoiding
- * race conditions.  Besides, we only expect modest, infrequent I/O for query
- * strings, so placing the file on a faster filesystem is not compelling.
+ * Location of external query text file.
  */
 #define PGSS_TEXT_FILE	PG_STAT_TMP_DIR "/pgss_query_texts.stat"
 

src/backend/postmaster/pgstat.c

@@ -186,16 +186,6 @@ bool		pgstat_track_counts = false;
 int			pgstat_fetch_consistency = PGSTAT_FETCH_CONSISTENCY_NONE;
 
 
-/* ----------
- * Built from GUC parameter
- * ----------
- */
-
-char	   *pgstat_stat_directory = NULL;
-char	   *pgstat_stat_filename = NULL;
-char	   *pgstat_stat_tmpname = NULL;
-
-
 /* ----------
  * state shared with pgstat_*.c
  * ----------

src/backend/replication/basebackup.c

@@ -99,9 +99,6 @@ static int	basebackup_read_file(int fd, char *buf, size_t nbytes, off_t offset,
 /* Was the backup currently in-progress initiated in recovery mode? */
 static bool backup_started_in_recovery = false;
 
-/* Relative path of temporary statistics directory */
-static char *statrelpath = NULL;
-
 /* Total number of checksum failures during base backup. */
 static long long int total_checksum_failures;
 
@@ -131,9 +128,8 @@ struct exclude_list_item
 static const char *const excludeDirContents[] =
 {
 	/*
-	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
-	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always
-	 * created there.
+	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped
+	 * because extensions like pg_stat_statements store data there.
 	 */
 	PG_STAT_TMP_DIR,
 
@@ -237,7 +233,6 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 	StringInfo	labelfile;
 	StringInfo	tblspc_map_file;
 	backup_manifest_info manifest;
-	int			datadirpathlen;
 
 	/* Initial backup state, insofar as we know it now. */
 	state.tablespaces = NIL;
@@ -250,8 +245,6 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 	Assert(CurrentResourceOwner == NULL);
 	CurrentResourceOwner = ResourceOwnerCreate(NULL, "base backup");
 
-	datadirpathlen = strlen(DataDir);
-
 	backup_started_in_recovery = RecoveryInProgress();
 
 	labelfile = makeStringInfo();
@@ -279,18 +272,6 @@ perform_base_backup(basebackup_options *opt, bbsink *sink)
 		ListCell   *lc;
 		tablespaceinfo *ti;
 
-		/*
-		 * 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;
-
 		/* Add a node for the base directory at the end */
 		ti = palloc0(sizeof(tablespaceinfo));
 		ti->size = -1;
@@ -1310,19 +1291,6 @@ sendDir(bbsink *sink, const char *path, int basepathlen, bool sizeonly,
 		if (excludeFound)
 			continue;
 
-		/*
-		 * Exclude contents of directory specified by statrelpath if not set
-		 * to the default (pg_stat_tmp) which is caught in the loop above.
-		 */
-		if (statrelpath != NULL && strcmp(pathbuf, statrelpath) == 0)
-		{
-			elog(DEBUG1, "contents of directory \"%s\" excluded from backup", statrelpath);
-			convert_link_to_directory(pathbuf, &statbuf);
-			size += _tarWriteHeader(sink, pathbuf + basepathlen + 1, NULL,
-									&statbuf, sizeonly);
-			continue;
-		}
-
 		/*
 		 * We can skip pg_wal, the WAL segments need to be fetched from the
 		 * WAL archive anyway. But include it as an empty directory anyway, so

src/backend/utils/misc/guc.c

@@ -217,7 +217,6 @@ static bool check_effective_io_concurrency(int *newval, void **extra, GucSource
 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 bool check_client_connection_check_interval(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);
@@ -4560,17 +4559,6 @@ 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_PRIMARY,
 			gettext_noop("Number of synchronous standbys and list of names of potential synchronous ones."),
@@ -12375,35 +12363,6 @@ check_client_connection_check_interval(int *newval, void **extra, GucSource sour
 	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)
 {

src/backend/utils/misc/postgresql.conf.sample

@@ -613,7 +613,6 @@
 #track_io_timing = off
 #track_wal_io_timing = off
 #track_functions = none			# none, pl, all
-#stats_temp_directory = 'pg_stat_tmp'
 #stats_fetch_consistency = none
 
 

src/bin/pg_rewind/filemap.c

@@ -88,9 +88,8 @@ struct exclude_list_item
 static const char *excludeDirContents[] =
 {
 	/*
-	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
-	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always
-	 * created there.
+	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped
+	 * because extensions like pg_stat_statements store data there.
 	 */
 	"pg_stat_tmp",				/* defined as PG_STAT_TMP_DIR */
 

src/include/pgstat.h

@@ -642,10 +642,6 @@ extern PGDLLIMPORT bool pgstat_track_counts;
 extern PGDLLIMPORT int pgstat_track_functions;
 extern PGDLLIMPORT int pgstat_fetch_consistency;
 
-extern char *pgstat_stat_directory;
-extern char *pgstat_stat_tmpname;
-extern char *pgstat_stat_filename;
-
 
 /*
  * Variables in pgstat_bgwriter.c

src/test/perl/PostgreSQL/Test/Cluster.pm

@@ -480,10 +480,6 @@ sub init
 	print $conf PostgreSQL::Test::Utils::slurp_file($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")