Avoid race in RelationBuildDesc() affecting CREATE INDEX CONCURRENTLY.

CIC and REINDEX CONCURRENTLY assume backends see their catalog changes
no later than each backend's next transaction start.  That failed to
hold when a backend absorbed a relevant invalidation in the middle of
running RelationBuildDesc() on the CIC index.  Queries that use the
resulting index can silently fail to find rows.  Fix this for future
index builds by making RelationBuildDesc() loop until it finishes
without accepting a relevant invalidation.  It may be necessary to
reindex to recover from past occurrences; REINDEX CONCURRENTLY suffices.
Back-patch to 9.6 (all supported versions).

Noah Misch and Andrey Borodin, reviewed (in earlier versions) by Andres
Freund.

Discussion: https://postgr.es/m/20210730022548.GA1940096@gust.leadboat.com

contrib/amcheck/t/002_cic.pl

@@ -0,0 +1,78 @@
+
+# Copyright (c) 2021, PostgreSQL Global Development Group
+
+# Test CREATE INDEX CONCURRENTLY with concurrent modifications
+use strict;
+use warnings;
+
+use Config;
+use PostgresNode;
+use TestLib;
+
+use Test::More tests => 4;
+
+my ($node, $result);
+
+#
+# Test set-up
+#
+$node = PostgresNode->new('CIC_test');
+$node->init;
+$node->append_conf('postgresql.conf', 'lock_timeout = 180000');
+$node->start;
+$node->safe_psql('postgres', q(CREATE EXTENSION amcheck));
+$node->safe_psql('postgres', q(CREATE TABLE tbl(i int)));
+$node->safe_psql('postgres', q(CREATE INDEX idx ON tbl(i)));
+
+#
+# Stress CIC with pgbench
+#
+
+# Run background pgbench with CIC. We cannot mix-in this script into single
+# pgbench: CIC will deadlock with itself occasionally.
+my $pgbench_out   = '';
+my $pgbench_timer = IPC::Run::timeout(180);
+my $pgbench_h     = $node->background_pgbench(
+	'--no-vacuum --client=1 --transactions=200',
+	{
+		'002_pgbench_concurrent_cic' => q(
+			DROP INDEX CONCURRENTLY idx;
+			CREATE INDEX CONCURRENTLY idx ON tbl(i);
+			SELECT bt_index_check('idx',true);
+		   )
+	},
+	\$pgbench_out,
+	$pgbench_timer);
+
+# Run pgbench.
+$node->pgbench(
+	'--no-vacuum --client=5 --transactions=200',
+	0,
+	[qr{actually processed}],
+	[qr{^$}],
+	'concurrent INSERTs',
+	{
+		'002_pgbench_concurrent_transaction' => q(
+			BEGIN;
+			INSERT INTO tbl VALUES(0);
+			COMMIT;
+		  ),
+		'002_pgbench_concurrent_transaction_savepoints' => q(
+			BEGIN;
+			SAVEPOINT s1;
+			INSERT INTO tbl VALUES(0);
+			COMMIT;
+		  )
+	});
+
+$pgbench_h->pump_nb;
+$pgbench_h->finish();
+$result =
+    ($Config{osname} eq "MSWin32")
+  ? ($pgbench_h->full_results)[0]
+  : $pgbench_h->result(0);
+is($result, 0, "pgbench with CIC works");
+
+# done
+$node->stop;
+done_testing();

src/backend/utils/cache/inval.c

@@ -628,7 +628,7 @@ LocalExecuteInvalidationMessage(SharedInvalidationMessage *msg)
 			int			i;
 
 			if (msg->rc.relId == InvalidOid)
-				RelationCacheInvalidate();
+				RelationCacheInvalidate(false);
 			else
 				RelationCacheInvalidateEntry(msg->rc.relId);
 
@@ -685,12 +685,18 @@ LocalExecuteInvalidationMessage(SharedInvalidationMessage *msg)
  */
 void
 InvalidateSystemCaches(void)
+{
+	InvalidateSystemCachesExtended(false);
+}
+
+void
+InvalidateSystemCachesExtended(bool debug_discard)
 {
 	int			i;
 
 	InvalidateCatalogSnapshot();
 	ResetCatalogCaches();
-	RelationCacheInvalidate();	/* gets smgr and relmap too */
+	RelationCacheInvalidate(debug_discard); /* gets smgr and relmap too */
 
 	for (i = 0; i < syscache_callback_count; i++)
 	{
@@ -759,7 +765,7 @@ AcceptInvalidationMessages(void)
 		if (recursion_depth < debug_discard_caches)
 		{
 			recursion_depth++;
-			InvalidateSystemCaches();
+			InvalidateSystemCachesExtended(true);
 			recursion_depth--;
 		}
 	}

src/backend/utils/cache/relcache.c

@@ -150,6 +150,24 @@ bool		criticalSharedRelcachesBuilt = false;
  */
 static long relcacheInvalsReceived = 0L;
 
+/*
+ * in_progress_list is a stack of ongoing RelationBuildDesc() calls.  CREATE
+ * INDEX CONCURRENTLY makes catalog changes under ShareUpdateExclusiveLock.
+ * It critically relies on each backend absorbing those changes no later than
+ * next transaction start.  Hence, RelationBuildDesc() loops until it finishes
+ * without accepting a relevant invalidation.  (Most invalidation consumers
+ * don't do this.)
+ */
+typedef struct inprogressent
+{
+	Oid			reloid;			/* OID of relation being built */
+	bool		invalidated;	/* whether an invalidation arrived for it */
+} InProgressEnt;
+
+static InProgressEnt *in_progress_list;
+static int	in_progress_list_len;
+static int	in_progress_list_maxlen;
+
 /*
  * eoxact_list[] stores the OIDs of relations that (might) need AtEOXact
  * cleanup work.  This list intentionally has limited size; if it overflows,
@@ -1000,6 +1018,7 @@ equalRSDesc(RowSecurityDesc *rsdesc1, RowSecurityDesc *rsdesc2)
 static Relation
 RelationBuildDesc(Oid targetRelId, bool insertIt)
 {
+	int			in_progress_offset;
 	Relation	relation;
 	Oid			relid;
 	HeapTuple	pg_class_tuple;
@@ -1033,6 +1052,21 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
 	}
 #endif
 
+	/* Register to catch invalidation messages */
+	if (in_progress_list_len >= in_progress_list_maxlen)
+	{
+		int			allocsize;
+
+		allocsize = in_progress_list_maxlen * 2;
+		in_progress_list = repalloc(in_progress_list,
+									allocsize * sizeof(*in_progress_list));
+		in_progress_list_maxlen = allocsize;
+	}
+	in_progress_offset = in_progress_list_len++;
+	in_progress_list[in_progress_offset].reloid = targetRelId;
+retry:
+	in_progress_list[in_progress_offset].invalidated = false;
+
 	/*
 	 * find the tuple in pg_class corresponding to the given relation id
 	 */
@@ -1051,6 +1085,8 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
 			MemoryContextDelete(tmpcxt);
 		}
 #endif
+		Assert(in_progress_offset + 1 == in_progress_list_len);
+		in_progress_list_len--;
 		return NULL;
 	}
 
@@ -1213,6 +1249,21 @@ RelationBuildDesc(Oid targetRelId, bool insertIt)
 	 */
 	heap_freetuple(pg_class_tuple);
 
+	/*
+	 * If an invalidation arrived mid-build, start over.  Between here and the
+	 * end of this function, don't add code that does or reasonably could read
+	 * system catalogs.  That range must be free from invalidation processing
+	 * for the !insertIt case.  For the insertIt case, RelationCacheInsert()
+	 * will enroll this relation in ordinary relcache invalidation processing,
+	 */
+	if (in_progress_list[in_progress_offset].invalidated)
+	{
+		RelationDestroyRelation(relation, false);
+		goto retry;
+	}
+	Assert(in_progress_offset + 1 == in_progress_list_len);
+	in_progress_list_len--;
+
 	/*
 	 * Insert newly created relation into relcache hash table, if requested.
 	 *
@@ -2566,6 +2617,14 @@ RelationClearRelation(Relation relation, bool rebuild)
 
 		/* Build temporary entry, but don't link it into hashtable */
 		newrel = RelationBuildDesc(save_relid, false);
+
+		/*
+		 * Between here and the end of the swap, don't add code that does or
+		 * reasonably could read system catalogs.  That range must be free
+		 * from invalidation processing.  See RelationBuildDesc() manipulation
+		 * of in_progress_list.
+		 */
+
 		if (newrel == NULL)
 		{
 			/*
@@ -2805,6 +2864,14 @@ RelationCacheInvalidateEntry(Oid relationId)
 		relcacheInvalsReceived++;
 		RelationFlushRelation(relation);
 	}
+	else
+	{
+		int			i;
+
+		for (i = 0; i < in_progress_list_len; i++)
+			if (in_progress_list[i].reloid == relationId)
+				in_progress_list[i].invalidated = true;
+	}
 }
 
 /*
@@ -2813,11 +2880,11 @@ RelationCacheInvalidateEntry(Oid relationId)
  *	 and rebuild those with positive reference counts.  Also reset the smgr
  *	 relation cache and re-read relation mapping data.
  *
- *	 This is currently used only to recover from SI message buffer overflow,
+ *	 Apart from debug_discard_caches, this is currently used only to recover
- *	 so we do not touch relations having new-in-transaction relfilenodes; they
+ *	 from SI message buffer overflow, so we do not touch relations having
- *	 cannot be targets of cross-backend SI updates (and our own updates now go
+ *	 new-in-transaction relfilenodes; they cannot be targets of cross-backend
- *	 through a separate linked list that isn't limited by the SI message
+ *	 SI updates (and our own updates now go through a separate linked list
- *	 buffer size).
+ *	 that isn't limited by the SI message buffer size).
  *
  *	 We do this in two phases: the first pass deletes deletable items, and
  *	 the second one rebuilds the rebuildable items.  This is essential for
@@ -2835,9 +2902,14 @@ RelationCacheInvalidateEntry(Oid relationId)
  *	 second pass processes nailed-in-cache items before other nondeletable
  *	 items.  This should ensure that system catalogs are up to date before
  *	 we attempt to use them to reload information about other open relations.
+ *
+ *	 After those two phases of work having immediate effects, we normally
+ *	 signal any RelationBuildDesc() on the stack to start over.  However, we
+ *	 don't do this if called as part of debug_discard_caches.  Otherwise,
+ *	 RelationBuildDesc() would become an infinite loop.
  */
 void
-RelationCacheInvalidate(void)
+RelationCacheInvalidate(bool debug_discard)
 {
 	HASH_SEQ_STATUS status;
 	RelIdCacheEnt *idhentry;
@@ -2845,6 +2917,7 @@ RelationCacheInvalidate(void)
 	List	   *rebuildFirstList = NIL;
 	List	   *rebuildList = NIL;
 	ListCell   *l;
+	int			i;
 
 	/*
 	 * Reload relation mapping data before starting to reconstruct cache.
@@ -2931,6 +3004,11 @@ RelationCacheInvalidate(void)
 		RelationClearRelation(relation, true);
 	}
 	list_free(rebuildList);
+
+	if (!debug_discard)
+		/* Any RelationBuildDesc() on the stack must start over. */
+		for (i = 0; i < in_progress_list_len; i++)
+			in_progress_list[i].invalidated = true;
 }
 
 /*
@@ -3081,6 +3159,13 @@ AtEOXact_RelationCache(bool isCommit)
 	RelIdCacheEnt *idhentry;
 	int			i;
 
+	/*
+	 * Forget in_progress_list.  This is relevant when we're aborting due to
+	 * an error during RelationBuildDesc().
+	 */
+	Assert(in_progress_list_len == 0 || !isCommit);
+	in_progress_list_len = 0;
+
 	/*
 	 * Unless the eoxact_list[] overflowed, we only need to examine the rels
 	 * listed in it.  Otherwise fall back on a hash_seq_search scan.
@@ -3227,6 +3312,14 @@ AtEOSubXact_RelationCache(bool isCommit, SubTransactionId mySubid,
 	RelIdCacheEnt *idhentry;
 	int			i;
 
+	/*
+	 * Forget in_progress_list.  This is relevant when we're aborting due to
+	 * an error during RelationBuildDesc().  We don't commit subtransactions
+	 * during RelationBuildDesc().
+	 */
+	Assert(in_progress_list_len == 0 || !isCommit);
+	in_progress_list_len = 0;
+
 	/*
 	 * Unless the eoxact_list[] overflowed, we only need to examine the rels
 	 * listed in it.  Otherwise fall back on a hash_seq_search scan.  Same
@@ -3775,6 +3868,7 @@ void
 RelationCacheInitialize(void)
 {
 	HASHCTL		ctl;
+	int			allocsize;
 
 	/*
 	 * make sure cache memory context exists
@@ -3790,6 +3884,15 @@ RelationCacheInitialize(void)
 	RelationIdCache = hash_create("Relcache by OID", INITRELCACHESIZE,
 								  &ctl, HASH_ELEM | HASH_BLOBS);
 
+	/*
+	 * reserve enough in_progress_list slots for many cases
+	 */
+	allocsize = 4;
+	in_progress_list =
+		MemoryContextAlloc(CacheMemoryContext,
+						   allocsize * sizeof(*in_progress_list));
+	in_progress_list_maxlen = allocsize;
+
 	/*
 	 * relation mapper needs to be initialized too
 	 */

src/bin/pgbench/t/001_pgbench_with_server.pl

@@ -14,54 +14,6 @@ my $node = PostgresNode->new('main');
 $node->init;
 $node->start;
 
-# invoke pgbench, with parameters:
-#   $opts: options as a string to be split on spaces
-#   $stat: expected exit status
-#   $out: reference to a regexp list that must match stdout
-#   $err: reference to a regexp list that must match stderr
-#   $name: name of test for error messages
-#   $files: reference to filename/contents dictionary
-#   @args: further raw options or arguments
-sub pgbench
-{
-	local $Test::Builder::Level = $Test::Builder::Level + 1;
-
-	my ($opts, $stat, $out, $err, $name, $files, @args) = @_;
-	my @cmd = ('pgbench', split /\s+/, $opts);
-	my @filenames = ();
-	if (defined $files)
-	{
-
-		# note: files are ordered for determinism
-		for my $fn (sort keys %$files)
-		{
-			my $filename = $node->basedir . '/' . $fn;
-			push @cmd, '-f', $filename;
-
-			# cleanup file weight
-			$filename =~ s/\@\d+$//;
-
-			#push @filenames, $filename;
-			# filenames are expected to be unique on a test
-			if (-e $filename)
-			{
-				ok(0, "$filename must not already exist");
-				unlink $filename or die "cannot unlink $filename: $!";
-			}
-			append_to_file($filename, $$files{$fn});
-		}
-	}
-
-	push @cmd, @args;
-
-	$node->command_checks_all(\@cmd, $stat, $out, $err, $name);
-
-	# cleanup?
-	#unlink @filenames or die "cannot unlink files (@filenames): $!";
-
-	return;
-}
-
 # tablespace for testing, because partitioned tables cannot use pg_default
 # explicitly and we want to test that table creation with tablespace works
 # for partitioned tables.
@@ -77,7 +29,7 @@ $node->safe_psql('postgres',
 # Test concurrent OID generation via pg_enum_oid_index.  This indirectly
 # exercises LWLock and spinlock concurrency.
 my $labels = join ',', map { "'l$_'" } 1 .. 1000;
-pgbench(
+$node->pgbench(
 	'--no-vacuum --client=5 --protocol=prepared --transactions=25',
 	0,
 	[qr{processed: 125/125}],
@@ -89,7 +41,7 @@ pgbench(
 	});
 
 # Trigger various connection errors
-pgbench(
+$node->pgbench(
 	'no-such-database',
 	1,
 	[qr{^$}],
@@ -99,13 +51,13 @@ pgbench(
 	],
 	'no such database');
 
-pgbench(
+$node->pgbench(
 	'-S -t 1', 1, [],
 	[qr{Perhaps you need to do initialization}],
 	'run without init');
 
 # Initialize pgbench tables scale 1
-pgbench(
+$node->pgbench(
 	'-i', 0,
 	[qr{^$}],
 	[
@@ -117,7 +69,7 @@ pgbench(
 	'pgbench scale 1 initialization',);
 
 # Again, with all possible options
-pgbench(
+$node->pgbench(
 	'--initialize --init-steps=dtpvg --scale=1 --unlogged-tables --fillfactor=98 --foreign-keys --quiet --tablespace=regress_pgbench_tap_1_ts --index-tablespace=regress_pgbench_tap_1_ts --partitions=2 --partition-method=hash',
 	0,
 	[qr{^$}i],
@@ -134,7 +86,7 @@ pgbench(
 	'pgbench scale 1 initialization');
 
 # Test interaction of --init-steps with legacy step-selection options
-pgbench(
+$node->pgbench(
 	'--initialize --init-steps=dtpvGvv --no-vacuum --foreign-keys --unlogged-tables --partitions=3',
 	0,
 	[qr{^$}],
@@ -151,7 +103,7 @@ pgbench(
 	'pgbench --init-steps');
 
 # Run all builtin scripts, for a few transactions each
-pgbench(
+$node->pgbench(
 	'--transactions=5 -Dfoo=bla --client=2 --protocol=simple --builtin=t'
 	  . ' --connect -n -v -n',
 	0,
@@ -164,7 +116,7 @@ pgbench(
 	[qr{^$}],
 	'pgbench tpcb-like');
 
-pgbench(
+$node->pgbench(
 	'--transactions=20 --client=5 -M extended --builtin=si -C --no-vacuum -s 1',
 	0,
 	[
@@ -177,7 +129,7 @@ pgbench(
 	[qr{scale option ignored}],
 	'pgbench simple update');
 
-pgbench(
+$node->pgbench(
 	'-t 100 -c 7 -M prepared -b se --debug',
 	0,
 	[
@@ -203,7 +155,7 @@ my $nthreads = 2;
 }
 
 # run custom scripts
-pgbench(
+$node->pgbench(
 	"-t 100 -c 1 -j $nthreads -M prepared -n",
 	0,
 	[
@@ -233,7 +185,7 @@ COMMIT;
 }
 	});
 
-pgbench(
+$node->pgbench(
 	'-n -t 10 -c 1 -M simple',
 	0,
 	[
@@ -254,7 +206,7 @@ COMMIT;
 }
 	});
 
-pgbench(
+$node->pgbench(
 	'-n -t 10 -c 2 -M extended',
 	0,
 	[
@@ -285,7 +237,7 @@ $node->append_conf('postgresql.conf',
 	  . "log_parameter_max_length = 0\n"
 	  . "log_parameter_max_length_on_error = 0");
 $node->reload;
-pgbench(
+$node->pgbench(
 	'-n -t1 -c1 -M prepared',
 	2,
 	[],
@@ -312,7 +264,7 @@ $node->append_conf('postgresql.conf',
 	    "log_parameter_max_length = -1\n"
 	  . "log_parameter_max_length_on_error = 64");
 $node->reload;
-pgbench(
+$node->pgbench(
 	'-n -t1 -c1 -M prepared',
 	2,
 	[],
@@ -326,7 +278,7 @@ pgbench(
 SELECT 1 / (random() / 2)::int, :one::int, :two::int;
 }
 	});
-pgbench(
+$node->pgbench(
 	'-n -t1 -c1 -M prepared',
 	2,
 	[],
@@ -354,7 +306,7 @@ $node->append_conf('postgresql.conf',
 	  . "log_parameter_max_length = 7\n"
 	  . "log_parameter_max_length_on_error = -1");
 $node->reload;
-pgbench(
+$node->pgbench(
 	'-n -t1 -c1 -M prepared',
 	2,
 	[],
@@ -371,7 +323,7 @@ SELECT 1 / (random() / 2)::int, :one::int, :two::int;
 
 $node->append_conf('postgresql.conf', "log_min_duration_statement = 0");
 $node->reload;
-pgbench(
+$node->pgbench(
 	'-n -t1 -c1 -M prepared',
 	2,
 	[],
@@ -394,7 +346,7 @@ like(
 $log = undef;
 
 # Check that bad parameters are reported during typinput phase of BIND
-pgbench(
+$node->pgbench(
 	'-n -t1 -c1 -M prepared',
 	2,
 	[],
@@ -418,7 +370,7 @@ $node->reload;
 
 # test expressions
 # command 1..3 and 23 depend on random seed which is used to call srandom.
-pgbench(
+$node->pgbench(
 	'--random-seed=5432 -t 1 -Dfoo=-10.1 -Dbla=false -Di=+3 -Dn=null -Dt=t -Df=of -Dd=1.0',
 	0,
 	[ qr{type: .*/001_pgbench_expressions}, qr{processed: 1/1} ],
@@ -653,7 +605,7 @@ $node->safe_psql('postgres',
 my $seed = int(rand(1000000000));
 for my $i (1, 2)
 {
-	pgbench(
+	$node->pgbench(
 		"--random-seed=$seed -t 1",
 		0,
 		[qr{processed: 1/1}],
@@ -693,7 +645,7 @@ ok($out =~ /\b$seed\|zipfian\|4\d\d\d\|2/,
 $node->safe_psql('postgres', 'DROP TABLE seeded_random;');
 
 # backslash commands
-pgbench(
+$node->pgbench(
 	'-t 1', 0,
 	[
 		qr{type: .*/001_pgbench_backslash_commands},
@@ -722,7 +674,7 @@ pgbench(
 	});
 
 # working \gset
-pgbench(
+$node->pgbench(
 	'-t 1', 0,
 	[ qr{type: .*/001_pgbench_gset}, qr{processed: 1/1} ],
 	[
@@ -757,7 +709,7 @@ SELECT 0 AS i4, 4 AS i4 \gset
 }
 	});
 # \gset cannot accept more than one row, causing command to fail.
-pgbench(
+$node->pgbench(
 	'-t 1', 2,
 	[ qr{type: .*/001_pgbench_gset_two_rows}, qr{processed: 0/1} ],
 	[qr{expected one row, got 2\b}],
@@ -770,7 +722,7 @@ SELECT 5432 AS fail UNION SELECT 5433 ORDER BY 1 \gset
 
 # working \aset
 # Valid cases.
-pgbench(
+$node->pgbench(
 	'-t 1', 0,
 	[ qr{type: .*/001_pgbench_aset}, qr{processed: 1/1} ],
 	[ qr{command=3.: int 8\b},       qr{command=4.: int 7\b} ],
@@ -786,7 +738,7 @@ SELECT 8 AS i6 UNION SELECT 9 ORDER BY 1 DESC \aset
 }
 	});
 # Empty result set with \aset, causing command to fail.
-pgbench(
+$node->pgbench(
 	'-t 1', 2,
 	[ qr{type: .*/001_pgbench_aset_empty}, qr{processed: 0/1} ],
 	[
@@ -803,7 +755,7 @@ pgbench(
 	});
 
 # Working \startpipeline
-pgbench(
+$node->pgbench(
 	'-t 1 -n -M extended',
 	0,
 	[ qr{type: .*/001_pgbench_pipeline}, qr{actually processed: 1/1} ],
@@ -819,7 +771,7 @@ pgbench(
 	});
 
 # Working \startpipeline in prepared query mode
-pgbench(
+$node->pgbench(
 	'-t 1 -n -M prepared',
 	0,
 	[ qr{type: .*/001_pgbench_pipeline_prep}, qr{actually processed: 1/1} ],
@@ -835,7 +787,7 @@ pgbench(
 	});
 
 # Try \startpipeline twice
-pgbench(
+$node->pgbench(
 	'-t 1 -n -M extended',
 	2,
 	[],
@@ -850,7 +802,7 @@ pgbench(
 	});
 
 # Try to end a pipeline that hasn't started
-pgbench(
+$node->pgbench(
 	'-t 1 -n -M extended',
 	2,
 	[],
@@ -864,7 +816,7 @@ pgbench(
 	});
 
 # Try \gset in pipeline mode
-pgbench(
+$node->pgbench(
 	'-t 1 -n -M extended',
 	2,
 	[],
@@ -1129,7 +1081,7 @@ for my $e (@errors)
 	$status != 0 or die "invalid expected status for test \"$name\"";
 	my $n = '001_pgbench_error_' . $name;
 	$n =~ s/ /_/g;
-	pgbench(
+	$node->pgbench(
 		'-n -t 1 -Dfoo=bla -Dnull=null -Dtrue=true -Done=1 -Dzero=0.0 -Dbadtrue=trueXXX'
 		  . ' -Dmaxint=9223372036854775807 -Dminint=-9223372036854775808'
 		  . ($no_prepare ? '' : ' -M prepared'),
@@ -1141,14 +1093,14 @@ for my $e (@errors)
 }
 
 # throttling
-pgbench(
+$node->pgbench(
 	'-t 100 -S --rate=100000 --latency-limit=1000000 -c 2 -n -r',
 	0,
 	[ qr{processed: 200/200}, qr{builtin: select only} ],
 	[qr{^$}],
 	'pgbench throttling');
 
-pgbench(
+$node->pgbench(
 
 	# given the expected rate and the 2 ms tx duration, at most one is executed
 	'-t 10 --rate=100000 --latency-limit=1 -n -r',
@@ -1220,7 +1172,7 @@ sub check_pgbench_logs
 my $bdir = $node->basedir;
 
 # Run with sampling rate, 2 clients with 50 transactions each.
-pgbench(
+$node->pgbench(
 	"-n -S -t 50 -c 2 --log --sampling-rate=0.5", 0,
 	[ qr{select only}, qr{processed: 100/100} ], [qr{^$}],
 	'pgbench logs', undef,
@@ -1230,7 +1182,7 @@ check_pgbench_logs($bdir, '001_pgbench_log_2', 1, 8, 92,
 	qr{^[01] \d{1,2} \d+ \d \d+ \d+$});
 
 # Run with different read-only option pattern, 1 client with 10 transactions.
-pgbench(
+$node->pgbench(
 	"-n -b select-only -t 10 -l", 0,
 	[ qr{select only}, qr{processed: 10/10} ], [qr{^$}],
 	'pgbench logs contents', undef,

src/include/utils/inval.h

@@ -62,6 +62,7 @@ extern void CacheRegisterRelcacheCallback(RelcacheCallbackFunction func,
 extern void CallSyscacheCallbacks(int cacheid, uint32 hashvalue);
 
 extern void InvalidateSystemCaches(void);
+extern void InvalidateSystemCachesExtended(bool debug_discard);
 
 extern void LogLogicalInvalidations(void);
 #endif							/* INVAL_H */

src/include/utils/relcache.h

@@ -122,7 +122,7 @@ extern void RelationForgetRelation(Oid rid);
 
 extern void RelationCacheInvalidateEntry(Oid relationId);
 
-extern void RelationCacheInvalidate(void);
+extern void RelationCacheInvalidate(bool debug_discard);
 
 extern void RelationCloseSmgrByOid(Oid relationId);
 

src/test/perl/PostgresNode.pm

@@ -1982,6 +1982,140 @@ sub interactive_psql
 	return $harness;
 }
 
+# Common sub of pgbench-invoking interfaces.  Makes any requested script files
+# and returns pgbench command-line options causing use of those files.
+sub _pgbench_make_files
+{
+	my ($self, $files) = @_;
+	my @file_opts;
+
+	if (defined $files)
+	{
+
+		# note: files are ordered for determinism
+		for my $fn (sort keys %$files)
+		{
+			my $filename = $self->basedir . '/' . $fn;
+			push @file_opts, '-f', $filename;
+
+			# cleanup file weight
+			$filename =~ s/\@\d+$//;
+
+			#push @filenames, $filename;
+			# filenames are expected to be unique on a test
+			if (-e $filename)
+			{
+				ok(0, "$filename must not already exist");
+				unlink $filename or die "cannot unlink $filename: $!";
+			}
+			TestLib::append_to_file($filename, $$files{$fn});
+		}
+	}
+
+	return @file_opts;
+}
+
+=pod
+
+=item $node->pgbench($opts, $stat, $out, $err, $name, $files, @args)
+
+Invoke B<pgbench>, with parameters and files.
+
+=over
+
+=item $opts
+
+Options as a string to be split on spaces.
+
+=item $stat
+
+Expected exit status.
+
+=item $out
+
+Reference to a regexp list that must match stdout.
+
+=item $err
+
+Reference to a regexp list that must match stderr.
+
+=item $name
+
+Name of test for error messages.
+
+=item $files
+
+Reference to filename/contents dictionary.
+
+=item @args
+
+Further raw options or arguments.
+
+=back
+
+=cut
+
+sub pgbench
+{
+	local $Test::Builder::Level = $Test::Builder::Level + 1;
+
+	my ($self, $opts, $stat, $out, $err, $name, $files, @args) = @_;
+	my @cmd = (
+		'pgbench',
+		split(/\s+/, $opts),
+		$self->_pgbench_make_files($files), @args);
+
+	$self->command_checks_all(\@cmd, $stat, $out, $err, $name);
+}
+
+=pod
+
+=item $node->background_pgbench($opts, $files, \$stdout, $timer) => harness
+
+Invoke B<pgbench> and return an IPC::Run harness object.  The process's stdin
+is empty, and its stdout and stderr go to the $stdout scalar reference.  This
+allows the caller to act on other parts of the system while B<pgbench> is
+running.  Errors from B<pgbench> are the caller's problem.
+
+The specified timer object is attached to the harness, as well.  It's caller's
+responsibility to select the timeout length, and to restart the timer after
+each command if the timeout is per-command.
+
+Be sure to "finish" the harness when done with it.
+
+=over
+
+=item $opts
+
+Options as a string to be split on spaces.
+
+=item $files
+
+Reference to filename/contents dictionary.
+
+=back
+
+=cut
+
+sub background_pgbench
+{
+	my ($self, $opts, $files, $stdout, $timer) = @_;
+
+	my @cmd =
+	  ('pgbench', split(/\s+/, $opts), $self->_pgbench_make_files($files));
+
+	local %ENV = $self->_get_env();
+
+	my $stdin = "";
+	# IPC::Run would otherwise append to existing contents:
+	$$stdout = "" if ref($stdout);
+
+	my $harness = IPC::Run::start \@cmd, '<', \$stdin, '>', $stdout, '2>&1',
+	  $timer;
+
+	return $harness;
+}
+
 =pod
 
 =item $node->connect_ok($connstr, $test_name, %params)

src/tools/pgindent/typedefs.list

@@ -1093,6 +1093,7 @@ ImportForeignSchemaStmt
 ImportForeignSchemaType
 ImportForeignSchema_function
 ImportQual
+InProgressEnt
 IncludeWal
 InclusionOpaque
 IncrementVarSublevelsUp_context