diff --git a/contrib/amcheck/t/002_cic.pl b/contrib/amcheck/t/002_cic.pl
new file mode 100644
index 0000000000..fd2dbc3366
--- /dev/null
+++ b/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();
diff --git a/src/backend/utils/cache/inval.c b/src/backend/utils/cache/inval.c
index 9352c68090..dd8586ab4d 100644
--- a/src/backend/utils/cache/inval.c
+++ b/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--;
 		}
 	}
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 13d9994af3..b54c911766 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/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,
- *	 so we do not touch relations having new-in-transaction relfilenodes; they
- *	 cannot be targets of cross-backend SI updates (and our own updates now go
- *	 through a separate linked list that isn't limited by the SI message
- *	 buffer size).
+ *	 Apart from debug_discard_caches, this is currently used only to recover
+ *	 from SI message buffer overflow, so we do not touch relations having
+ *	 new-in-transaction relfilenodes; they cannot be targets of cross-backend
+ *	 SI updates (and our own updates now go through a separate linked list
+ *	 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
 	 */
diff --git a/src/bin/pgbench/t/001_pgbench_with_server.pl b/src/bin/pgbench/t/001_pgbench_with_server.pl
index ef53f6b2d9..7ca96e58ca 100644
--- a/src/bin/pgbench/t/001_pgbench_with_server.pl
+++ b/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,
diff --git a/src/include/utils/inval.h b/src/include/utils/inval.h
index 770672890b..877e66c63c 100644
--- a/src/include/utils/inval.h
+++ b/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 */
diff --git a/src/include/utils/relcache.h b/src/include/utils/relcache.h
index d2c17575f6..aa060ef115 100644
--- a/src/include/utils/relcache.h
+++ b/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);
 
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
index ba80baf091..465fdb6870 100644
--- a/src/test/perl/PostgresNode.pm
+++ b/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)
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index cb5b5ec74c..1c7bac0578 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -1093,6 +1093,7 @@ ImportForeignSchemaStmt
 ImportForeignSchemaType
 ImportForeignSchema_function
 ImportQual
+InProgressEnt
 IncludeWal
 InclusionOpaque
 IncrementVarSublevelsUp_context