diff --git a/aqo.c b/aqo.c
index 4cfe0ee4..935d8711 100644
--- a/aqo.c
+++ b/aqo.c
@@ -275,8 +275,8 @@ _PG_init(void)
 							&dsm_size_max,
 							100,
 							0, INT_MAX,
-							PGC_SUSET,
-							0,
+							PGC_POSTMASTER,
+							GUC_UNIT_MB,
 							NULL,
 							NULL,
 							NULL
@@ -388,5 +388,5 @@ PG_FUNCTION_INFO_V1(invalidate_deactivated_queries_cache);
 Datum
 invalidate_deactivated_queries_cache(PG_FUNCTION_ARGS)
 {
-       PG_RETURN_POINTER(NULL);
+	PG_RETURN_POINTER(NULL);
 }
diff --git a/aqo_shared.c b/aqo_shared.c
index 0a86ea09..d9b56f38 100644
--- a/aqo_shared.c
+++ b/aqo_shared.c
@@ -98,6 +98,8 @@ aqo_init_shmem(void)
 		 /* Doesn't use DSA, so can be loaded in postmaster */
 		aqo_stat_load();
 		aqo_queries_load();
+
+		check_dsa_file_size();
 	}
 }
 
diff --git a/preprocessing.c b/preprocessing.c
index feb28d39..6176bf52 100644
--- a/preprocessing.c
+++ b/preprocessing.c
@@ -280,14 +280,23 @@ aqo_planner(Query *parse, const char *query_string, int cursorOptions,
 						  query_context.learn_aqo, query_context.use_aqo,
 						  query_context.auto_tuning, &aqo_queries_nulls))
 		{
+			bool dsa_valid = true;
 			/*
 			 * Add query text into the ML-knowledge base. Just for further
 			 * analysis. In the case of cached plans we may have NULL query text.
 			 */
-			if (!aqo_qtext_store(query_context.query_hash, query_string))
+			if (!aqo_qtext_store(query_context.query_hash, query_string, &dsa_valid))
 			{
-				Assert(0); /* panic only on debug installation */
-				elog(ERROR, "[AQO] Impossible situation was detected. Maybe not enough of shared memory?");
+				if (!dsa_valid)
+				{
+					disable_aqo_for_query();
+					elog(WARNING, "[AQO] Not enough DSA. AQO was disabled for this query");
+				}
+				else
+				{
+					Assert(0); /* panic only on debug installation */
+					elog(ERROR, "[AQO] Impossible situation was detected. Maybe not enough of shared memory?");
+				}
 			}
 		}
 		else
diff --git a/storage.c b/storage.c
index f71f5207..a11f16f4 100644
--- a/storage.c
+++ b/storage.c
@@ -507,7 +507,7 @@ _form_qtext_record_cb(void *ctx, size_t *size)
 {
 	HASH_SEQ_STATUS *hash_seq = (HASH_SEQ_STATUS *) ctx;
 	QueryTextEntry	*entry;
-	void		    *data;
+	void			*data;
 	char			*query_string;
 	char			*ptr;
 
@@ -784,7 +784,7 @@ _deform_qtexts_record_cb(void *data, size_t size)
 										   HASH_ENTER, &found);
 	Assert(!found);
 
-	entry->qtext_dp = dsa_allocate(qtext_dsa, len);
+	entry->qtext_dp = dsa_allocate_extended(qtext_dsa, len, DSA_ALLOC_NO_OOM | DSA_ALLOC_ZERO);
 	if (!_check_dsa_validity(entry->qtext_dp))
 	{
 		/*
@@ -829,7 +829,7 @@ aqo_qtexts_load(void)
 
 	if (!found)
 	{
-		if (!aqo_qtext_store(0, "COMMON feature space (do not delete!)"))
+		if (!aqo_qtext_store(0, "COMMON feature space (do not delete!)", NULL))
 			elog(PANIC, "[AQO] DSA Initialization was unsuccessful");
 	}
 }
@@ -944,6 +944,49 @@ aqo_queries_load(void)
 	}
 }
 
+static long
+aqo_get_file_size(const char *filename)
+{
+	FILE   *file;
+	long	size = 0;
+
+	file = AllocateFile(filename, PG_BINARY_R);
+	if (file == NULL)
+	{
+		if (errno != ENOENT)
+			goto read_error;
+		return size;
+	}
+
+	fseek(file, 0L, SEEK_END);
+	size = ftell(file);
+
+	FreeFile(file);
+	return size;
+
+read_error:
+	ereport(LOG,
+			(errcode_for_file_access(),
+			 errmsg("could not read file \"%s\": %m", filename)));
+	if (file)
+		FreeFile(file);
+	unlink(filename);
+	return -1;
+}
+
+void
+check_dsa_file_size(void)
+{
+	long qtext_size = aqo_get_file_size(PGAQO_TEXT_FILE);
+	long data_size = aqo_get_file_size(PGAQO_DATA_FILE);
+
+	if (qtext_size == -1 || data_size == -1 ||
+		qtext_size + data_size >= dsm_size_max * 1024 * 1024)
+	{
+		elog(ERROR, "aqo.dsm_size_max is too small");
+	}
+}
+
 static void
 data_load(const char *filename, deform_record_t callback, void *ctx)
 {
@@ -1090,13 +1133,16 @@ dsa_init()
  * XXX: Maybe merge with aqo_queries ?
  */
 bool
-aqo_qtext_store(uint64 queryid, const char *query_string)
+aqo_qtext_store(uint64 queryid, const char *query_string, bool *dsa_valid)
 {
 	QueryTextEntry *entry;
 	bool			found;
 	bool			tblOverflow;
 	HASHACTION		action;
 
+	if (dsa_valid)
+		*dsa_valid = true;
+
 	Assert(!LWLockHeldByMe(&aqo_state->qtexts_lock));
 
 	if (query_string == NULL || querytext_max_size == 0)
@@ -1135,7 +1181,7 @@ aqo_qtext_store(uint64 queryid, const char *query_string)
 
 		entry->queryid = queryid;
 		size = size > querytext_max_size ? querytext_max_size : size;
-		entry->qtext_dp = dsa_allocate0(qtext_dsa, size);
+		entry->qtext_dp = dsa_allocate_extended(qtext_dsa, size, DSA_ALLOC_NO_OOM | DSA_ALLOC_ZERO);
 
 		if (!_check_dsa_validity(entry->qtext_dp))
 		{
@@ -1144,7 +1190,10 @@ aqo_qtext_store(uint64 queryid, const char *query_string)
 			 * that caller recognize it and don't try to call us more.
 			 */
 			(void) hash_search(qtexts_htab, &queryid, HASH_REMOVE, NULL);
+			_aqo_queries_remove(queryid);
 			LWLockRelease(&aqo_state->qtexts_lock);
+			if (dsa_valid)
+				*dsa_valid = false;
 			return false;
 		}
 
@@ -1423,7 +1472,7 @@ aqo_data_store(uint64 fs, int fss, AqoDataArgs *data, List *reloids)
 		entry->nrels = nrels;
 
 		size = _compute_data_dsa(entry);
-		entry->data_dp = dsa_allocate0(data_dsa, size);
+		entry->data_dp = dsa_allocate_extended(data_dsa, size, DSA_ALLOC_NO_OOM | DSA_ALLOC_ZERO);
 
 		if (!_check_dsa_validity(entry->data_dp))
 		{
@@ -1455,7 +1504,7 @@ aqo_data_store(uint64 fs, int fss, AqoDataArgs *data, List *reloids)
 
 		/* Need to re-allocate DSA chunk */
 		dsa_free(data_dsa, entry->data_dp);
-		entry->data_dp = dsa_allocate0(data_dsa, size);
+		entry->data_dp = dsa_allocate_extended(data_dsa, size, DSA_ALLOC_NO_OOM | DSA_ALLOC_ZERO);
 
 		if (!_check_dsa_validity(entry->data_dp))
 		{
@@ -2713,7 +2762,7 @@ aqo_query_texts_update(PG_FUNCTION_ARGS)
 
 	str_buff = (char*) palloc(str_len);
 	text_to_cstring_buffer(str, str_buff, str_len);
-	res = aqo_qtext_store(queryid, str_buff);
+	res = aqo_qtext_store(queryid, str_buff, NULL);
 	pfree(str_buff);
 
 	PG_RETURN_BOOL(res);
diff --git a/storage.h b/storage.h
index 2b4e4cdd..9491e33e 100644
--- a/storage.h
+++ b/storage.h
@@ -138,7 +138,7 @@ extern StatEntry *aqo_stat_store(uint64 queryid, bool use_aqo,
 extern void aqo_stat_flush(void);
 extern void aqo_stat_load(void);
 
-extern bool aqo_qtext_store(uint64 queryid, const char *query_string);
+extern bool aqo_qtext_store(uint64 queryid, const char *query_string, bool *dsa_valid);
 extern void aqo_qtexts_flush(void);
 extern void aqo_qtexts_load(void);
 
@@ -156,6 +156,7 @@ extern bool aqo_queries_store(uint64 queryid, uint64 fs, bool learn_aqo,
 extern void aqo_queries_flush(void);
 extern void aqo_queries_load(void);
 
+extern void check_dsa_file_size(void);
 /*
  * Machinery for deactivated queries cache.
  * TODO: Should live in a custom memory context
diff --git a/t/004_dsm_size_max.pl b/t/004_dsm_size_max.pl
new file mode 100644
index 00000000..1fe449fa
--- /dev/null
+++ b/t/004_dsm_size_max.pl
@@ -0,0 +1,76 @@
+use strict;
+use warnings;
+
+use Config;
+use PostgreSQL::Test::Cluster;
+use PostgreSQL::Test::Utils;
+
+use Test::More tests => 5;
+
+my $node = PostgreSQL::Test::Cluster->new('aqotest');
+$node->init;
+$node->append_conf('postgresql.conf', qq{
+shared_preload_libraries = 'aqo'
+aqo.mode = 'learn'
+log_statement = 'ddl'
+aqo.join_threshold = 0
+aqo.dsm_size_max = 4
+aqo.fs_max_items = 30000
+aqo.querytext_max_size = 1000000
+});
+
+# Disable connection default settings, forced by PGOPTIONS in AQO Makefile
+$ENV{PGOPTIONS}="";
+
+# General purpose variables.
+my $long_string = 'a' x 1000000;
+
+$node->start();
+$node->psql('postgres', 'CREATE EXTENSION aqo;');
+
+for my $i (1 .. 3) {
+	$node->psql('postgres', "select aqo_query_texts_update(" . $i . ", \'" . $long_string . "\');");
+}
+$node->stop();
+
+$node->adjust_conf('postgresql.conf', 'aqo.dsm_size_max', '1');
+is($node->start(fail_ok => 1),
+		0, "node fails to start");
+
+$node->adjust_conf('postgresql.conf', 'aqo.dsm_size_max', '4');
+is($node->start(),
+		1, "node starts");
+$node->psql('postgres', 'select * from aqo_reset();');
+
+$long_string = '1, ' x 10000;
+for my $i (1 .. 30) {
+	$node->psql('postgres', "select aqo_data_update(" . $i . ", 1, 1, '{{1}}', '{1}', '{1}', '{" . $long_string . " 1}');");
+}
+$node->stop();
+
+$node->adjust_conf('postgresql.conf', 'aqo.dsm_size_max', '1');
+is($node->start(fail_ok => 1),
+		0, "node fails to start");
+
+$node->adjust_conf('postgresql.conf', 'aqo.dsm_size_max', '4');
+is($node->start(),
+		1, "node starts");
+$node->psql('postgres', 'select * from aqo_reset();');
+$node->stop();
+
+my $regex;
+$long_string = 'a' x 100000;
+$regex = qr/.*WARNING:  \[AQO\] Not enough DSA\. AQO was disabled for this query/;
+$node->adjust_conf('postgresql.conf', 'aqo.dsm_size_max', '1');
+$node->start();
+my ($stdout, $stderr);
+for my $i (1 .. 20) {
+	$node->psql('postgres', "create table a as select s, md5(random()::text) from generate_Series(1,100) s;");
+	$node->psql('postgres',
+				"SELECT a.s FROM a CROSS JOIN ( SELECT '" . $long_string . "' as long_string) AS extra_rows;",
+				stdout => \$stdout, stderr => \$stderr);
+	$node->psql('postgres', "drop table a");
+}
+like($stderr, $regex, 'warning for exceeding the dsa limit');
+$node->stop;
+done_testing();