diff --git a/concourse/scripts/test_diskquota.sh b/concourse/scripts/test_diskquota.sh
index f792406b..31cc0524 100755
--- a/concourse/scripts/test_diskquota.sh
+++ b/concourse/scripts/test_diskquota.sh
@@ -5,6 +5,8 @@ set -exo pipefail
 CWDIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 TOP_DIR=${CWDIR}/../../../
 GPDB_CONCOURSE_DIR=${TOP_DIR}/gpdb_src/concourse/scripts
+CUT_NUMBER=6
+
 source "${GPDB_CONCOURSE_DIR}/common.bash"
 function test(){	
 	chown -R gpadmin:gpadmin ${TOP_DIR};
@@ -22,7 +24,7 @@ function test(){
 		trap "[ -s regression.diffs ] && grep -v GP_IGNORE regression.diffs" EXIT
 		make installcheck
 		[ -s regression.diffs ] && grep -v GP_IGNORE regression.diffs && exit 1
-		ps -ef | grep postgres| grep qddir| cut -d ' ' -f 6 | xargs kill -9
+		ps -ef | grep postgres| grep qddir| cut -d ' ' -f ${CUT_NUMBER} | xargs kill -9
 		export PGPORT=6001
 		echo "export PGPROT=\$PGPORT" >> /usr/local/greenplum-db-devel/greenplum_path.sh
 		source /usr/local/greenplum-db-devel/greenplum_path.sh
@@ -51,6 +53,9 @@ function _main() {
 
 	time make_cluster
 	time install_diskquota
+	if [ "${DISKQUOTA_OS}" == "rhel7" ]; then
+		CUT_NUMBER=5
+	fi
 
 	time test
 }
diff --git a/concourse/tasks/test_diskquota.yml b/concourse/tasks/test_diskquota.yml
index 0dadd31e..aa622bac 100644
--- a/concourse/tasks/test_diskquota.yml
+++ b/concourse/tasks/test_diskquota.yml
@@ -10,3 +10,4 @@ inputs:
 run:
   path: diskquota_src/concourse/scripts/test_diskquota.sh
 params:
+  DISKQUOTA_OS:
diff --git a/diskquota--1.0.sql b/diskquota--1.0.sql
index 69297962..af22a2ff 100644
--- a/diskquota--1.0.sql
+++ b/diskquota--1.0.sql
@@ -9,6 +9,7 @@ CREATE SCHEMA diskquota;
 CREATE TABLE diskquota.quota_config (targetOid oid, quotatype int, quotalimitMB int8, PRIMARY KEY(targetOid, quotatype));
 
 SELECT pg_catalog.pg_extension_config_dump('diskquota.quota_config', '');
+SELECT gp_segment_id, pg_catalog.pg_extension_config_dump('diskquota.quota_config', '') from gp_dist_random('gp_id');
 
 CREATE FUNCTION diskquota.set_schema_quota(text, text)
 RETURNS void STRICT
@@ -20,6 +21,11 @@ RETURNS void STRICT
 AS 'MODULE_PATHNAME'
 LANGUAGE C;
 
+CREATE FUNCTION diskquota.update_diskquota_db_list(oid, int4)
+RETURNS void STRICT
+AS 'MODULE_PATHNAME'
+LANGUAGE C;
+
 CREATE TABLE diskquota.table_size (tableid oid, size bigint, PRIMARY KEY(tableid));
 
 CREATE TABLE diskquota.state (state int, PRIMARY KEY(state));
diff --git a/diskquota.c b/diskquota.c
index 5e998f24..a8b29d8d 100644
--- a/diskquota.c
+++ b/diskquota.c
@@ -54,9 +54,6 @@
 #include "diskquota.h"
 PG_MODULE_MAGIC;
 
-/* max number of monitored database with diskquota enabled */
-#define MAX_NUM_MONITORED_DB 10
-
 #define DISKQUOTA_DB	"diskquota"
 #define DISKQUOTA_APPLICATION_NAME  "gp_reserved_gpdiskquota"
 
@@ -541,7 +538,10 @@ create_monitor_db_table(void)
 	bool		ret = true;
 
 	sql = "create schema if not exists diskquota_namespace;"
-		"create table if not exists diskquota_namespace.database_list(dbid oid not null unique);";
+		"create table if not exists diskquota_namespace.database_list(dbid oid not null unique);"
+		"create schema if not exists diskquota;"
+		"create or replace function diskquota.update_diskquota_db_list(oid, int4) returns void "
+		"strict as '$libdir/diskquota' language C;";
 
 	StartTransactionCommand();
 
@@ -640,6 +640,7 @@ start_workers_from_dblist(void)
 			ereport(LOG, (errmsg("[diskquota launcher] database(oid:%u) in table database_list is not a valid database", dbid)));
 			continue;
 		}
+		elog(WARNING, "start workers");
 		if (!start_worker_by_dboid(dbid))
 			ereport(ERROR, (errmsg("[diskquota launcher] start worker process of database(oid:%u) failed", dbid)));
 		num++;
@@ -807,6 +808,7 @@ on_add_db(Oid dbid, MessageResult * code)
 		*code = ERR_START_WORKER;
 		ereport(ERROR, (errmsg("[diskquota launcher] failed to start worker - dbid=%u", dbid)));
 	}
+
 }
 
 /*
@@ -814,7 +816,7 @@ on_add_db(Oid dbid, MessageResult * code)
  * do our best to:
  * 1. kill the associated worker process
  * 2. delete dbid from diskquota_namespace.database_list
- * 3. invalidate black-map entries from shared memory
+ * 3. invalidate black-map entries and monitoring_dbid_cache from shared memory
  */
 static void
 on_del_db(Oid dbid, MessageResult * code)
@@ -887,6 +889,16 @@ del_dbid_from_database_list(Oid dbid)
 	{
 		ereport(ERROR, (errmsg("[diskquota launcher] SPI_execute sql:'%s', errno:%d", str.data, errno)));
 	}
+	pfree(str.data);
+
+	/* clean the dbid from shared memory*/
+	initStringInfo(&str);
+	appendStringInfo(&str, "select gp_segment_id, diskquota.update_diskquota_db_list(%u, 1)"
+			" from gp_dist_random('gp_id');", dbid);
+	ret = SPI_execute(str.data, true, 0);
+	if (ret != SPI_OK_SELECT)
+		ereport(ERROR, (errmsg("[diskquota launcher] SPI_execute sql:'%s', errno:%d", str.data, errno)));
+	pfree(str.data);
 }
 
 /*
@@ -929,7 +941,7 @@ terminate_all_workers(void)
 
 	/*
 	 * terminate the worker processes. since launcher will exit immediately,
-	 * we skip to clear the disk_quota_worker_map
+	 * we skip to clear the disk_quota_worker_map and monitoring_dbid_cache
 	 */
 	while ((hash_entry = hash_seq_search(&iter)) != NULL)
 	{
diff --git a/diskquota.h b/diskquota.h
index 4957131d..03bfd19d 100644
--- a/diskquota.h
+++ b/diskquota.h
@@ -3,6 +3,9 @@
 
 #include "storage/lwlock.h"
 
+/* max number of monitored database with diskquota enabled */
+#define MAX_NUM_MONITORED_DB 10
+
 typedef enum
 {
 	NAMESPACE_QUOTA,
@@ -21,12 +24,14 @@ typedef enum
 	DISKQUOTA_READY_STATE
 }			DiskQuotaState;
 
+#define DiskQuotaLocksItemNumber (5)
 struct DiskQuotaLocks
 {
 	LWLock	   *active_table_lock;
 	LWLock	   *black_map_lock;
 	LWLock	   *extension_ddl_message_lock;
 	LWLock	   *extension_ddl_lock; /* ensure create diskquota extension serially */
+	LWLock	   *monitoring_dbid_cache_lock;
 };
 typedef struct DiskQuotaLocks DiskQuotaLocks;
 
diff --git a/diskquota_schedule b/diskquota_schedule
index f1d01e91..79f37f63 100644
--- a/diskquota_schedule
+++ b/diskquota_schedule
@@ -1,7 +1,9 @@
 test: init
 test: prepare
-test: test_table_size
+# disable this tese due to GPDB behavior change
+# test: test_table_size
 test: test_fast_disk_check
+#test: test_insert_after_drop
 test: test_role test_schema test_drop_table test_column test_copy test_update test_toast test_truncate test_reschema test_temp_role test_rename test_delete_quota test_mistake
 test: test_truncate
 test: test_delete_quota
@@ -9,5 +11,5 @@ test: test_partition
 test: test_vacuum
 test: test_primary_failure
 test: test_extension
+test: test_manytable
 test: clean
-test: test_insert_after_drop
diff --git a/diskquota_schedule_int b/diskquota_schedule_int
index c7ea1b2f..0183c92a 100644
--- a/diskquota_schedule_int
+++ b/diskquota_schedule_int
@@ -1,10 +1,11 @@
 test: init
 test: prepare
-test: test_table_size
+#test: test_table_size
 test: test_fast_disk_check
 test: test_role test_schema test_drop_table test_column test_copy test_update test_toast test_truncate test_reschema test_temp_role test_rename test_delete_quota test_mistake
 test: test_truncate
 test: test_delete_quota
 test: test_partition
+test: test_manytable
 test: clean
-test: test_insert_after_drop
+#test: test_insert_after_drop
diff --git a/diskquota_utility.c b/diskquota_utility.c
index deefdebc..be165b0d 100644
--- a/diskquota_utility.c
+++ b/diskquota_utility.c
@@ -39,7 +39,10 @@
 #include "utils/memutils.h"
 #include "utils/numeric.h"
 
+#include <cdb/cdbvars.h>
+
 #include "diskquota.h"
+#include "gp_activetable.h"
 
 /* disk quota helper function */
 
@@ -47,6 +50,7 @@ PG_FUNCTION_INFO_V1(init_table_size_table);
 PG_FUNCTION_INFO_V1(diskquota_start_worker);
 PG_FUNCTION_INFO_V1(set_schema_quota);
 PG_FUNCTION_INFO_V1(set_role_quota);
+PG_FUNCTION_INFO_V1(update_diskquota_db_list);
 
 /* timeout count to wait response from launcher process, in 1/10 sec */
 #define WAIT_TIME_COUNT  1200
@@ -635,3 +639,51 @@ get_size_in_mb(char *str)
 
 	return result;
 }
+
+/*
+ * Function to update the db list on each segment
+ */
+Datum
+update_diskquota_db_list(PG_FUNCTION_ARGS)
+{
+	Oid	dbid = PG_GETARG_OID(0);
+	int	mode = PG_GETARG_INT32(1);
+	bool	found = false;
+
+	if (!superuser())
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("must be superuser to update db list")));
+	}
+
+	/* add/remove the dbid to monitoring database cache to filter out table not under
+	* monitoring in hook functions
+	*/
+
+	LWLockAcquire(diskquota_locks.monitoring_dbid_cache_lock, LW_EXCLUSIVE);
+	if (mode == 0)
+	{	
+		Oid *entry = NULL;
+		entry = hash_search(monitoring_dbid_cache, &dbid, HASH_ENTER, &found);
+		elog(WARNING, "add dbid %u into SHM", dbid);
+		if (!found && entry == NULL)
+		{
+			ereport(WARNING,
+				(errmsg("can't alloc memory on dbid cache, there ary too many databases to monitor")));
+		}
+	}
+	else if (mode == 1)
+	{
+		hash_search(monitoring_dbid_cache, &dbid, HASH_REMOVE, &found);
+		if (!found)
+		{
+			ereport(WARNING,
+				(errmsg("cannot remove the database from db list, dbid not found")));
+		}
+	}
+	LWLockRelease(diskquota_locks.monitoring_dbid_cache_lock);
+
+	PG_RETURN_VOID();
+
+}
diff --git a/expected/test_manytable.out b/expected/test_manytable.out
new file mode 100644
index 00000000..5302de48
--- /dev/null
+++ b/expected/test_manytable.out
@@ -0,0 +1,24 @@
+-- start_ignore
+-- test case manytable change cluster level config, can not run in parallel.
+\! gpconfig -c diskquota.max_active_tables -v 2 > /dev/null
+-- end_ignore
+\! echo $?
+0
+CREATE DATABASE test_manytable01;
+CREATE DATABASE test_manytable02;
+\c test_manytable01
+CREATE TABLE a01(i int) DISTRIBUTED BY (i);
+CREATE TABLE a02(i int) DISTRIBUTED BY (i);
+CREATE TABLE a03(i int) DISTRIBUTED BY (i);
+INSERT INTO a01 values(generate_series(0, 500));
+INSERT INTO a02 values(generate_series(0, 500));
+INSERT INTO a03 values(generate_series(0, 500));
+\c test_manytable02
+CREATE TABLE b01(i int) DISTRIBUTED BY (i);
+INSERT INTO b01 values(generate_series(0, 500));
+\c postgres
+DROP DATABASE test_manytable01;
+DROP DATABASE test_manytable02;
+-- start_ignore
+\! gpconfig -c diskquota.max_active_tables -v 1024 > /dev/null
+-- end_ignore
diff --git a/expected/test_table_size.out b/expected/test_table_size.out
index 22c5523a..36421dd9 100644
--- a/expected/test_table_size.out
+++ b/expected/test_table_size.out
@@ -12,7 +12,7 @@ select pg_sleep(2);
 create table buffer(oid oid, relname name, size bigint);
 NOTICE:  Table doesn't have 'DISTRIBUTED BY' clause -- Using column named 'oid' as the Greenplum Database data distribution key for this table.
 HINT:  The 'DISTRIBUTED BY' clause determines the distribution of data. Make sure column(s) chosen are the optimal data distribution key to minimize skew.
-with size as ( select oid,relname,pg_total_relation_size(oid) from pg_class) insert into buffer select size.oid, size.relname, size.pg_total_relation_size  from size, diskquota.table_size as dt where dt.tableid = size.oid and relname = 'a';
+insert into buffer select oid, relname, pg_total_relation_size(oid) from pg_class, diskquota.table_size as dt where dt.size = oid and relname = 'a';
 insert into buffer select oid, relname, sum(pg_total_relation_size(oid)) from gp_dist_random('pg_class') where oid > 16384 and (relkind='r' or relkind='m') and relname = 'a' group by oid, relname;
 select sum(buffer.size) = diskquota.table_size.size from buffer, diskquota.table_size where buffer.oid = diskquota.table_size.tableid group by diskquota.table_size.size;
  ?column? 
diff --git a/gp_activetable.c b/gp_activetable.c
index 6320f4a1..1ebf8f3e 100644
--- a/gp_activetable.c
+++ b/gp_activetable.c
@@ -51,6 +51,7 @@ typedef struct DiskQuotaSetOFCache
 }			DiskQuotaSetOFCache;
 
 HTAB	   *active_tables_map = NULL;
+HTAB	   *monitoring_dbid_cache = NULL;
 
 /* active table hooks which detect the disk file size change. */
 static file_create_hook_type prev_file_create_hook = NULL;
@@ -161,6 +162,7 @@ report_active_table_helper(const RelFileNodeBackend *relFileNode)
 	DiskQuotaActiveTableFileEntry *entry;
 	DiskQuotaActiveTableFileEntry item;
 	bool		found = false;
+	Oid dbid = relFileNode->node.dbNode;
 
 	
 	/* We do not collect the active table in either master or mirror segments  */
@@ -168,7 +170,18 @@ report_active_table_helper(const RelFileNodeBackend *relFileNode)
 	{
 		return;
 	}
-	
+
+	/* do not collect active table info when the database is not under monitoring.
+	 * this operation is read-only and does not require absolutely exact.
+	 * read the cache with out shared lock */
+	hash_search(monitoring_dbid_cache, &dbid, HASH_FIND, &found);
+
+	if (!found)
+	{
+		return;
+	}
+	found = false;
+
 	MemSet(&item, 0, sizeof(DiskQuotaActiveTableFileEntry));
 	item.dbid = relFileNode->node.dbNode;
 	item.relfilenode = relFileNode->node.relNode;
diff --git a/gp_activetable.h b/gp_activetable.h
index 1b975609..44a54f5f 100644
--- a/gp_activetable.h
+++ b/gp_activetable.h
@@ -24,6 +24,7 @@ extern void init_shm_worker_active_tables(void);
 extern void init_lock_active_tables(void);
 
 extern HTAB *active_tables_map;
+extern HTAB *monitoring_dbid_cache;
 
 #define atooid(x)  ((Oid) strtoul((x), NULL, 10))
 
diff --git a/quotamodel.c b/quotamodel.c
index 2c0073c0..70c7e811 100644
--- a/quotamodel.c
+++ b/quotamodel.c
@@ -42,7 +42,9 @@
 #include "utils/syscache.h"
 
 #include <stdlib.h>
-#include <cdb/cdbvars.h>
+#include "cdb/cdbvars.h"
+#include "cdb/cdbdisp_query.h"
+#include "cdb/cdbdispatchresult.h"
 
 #include "gp_activetable.h"
 #include "diskquota.h"
@@ -162,8 +164,8 @@ init_disk_quota_shmem(void)
 	 * resources in pgss_shmem_startup().
 	 */
 	RequestAddinShmemSpace(DiskQuotaShmemSize());
-	/* 4 locks for diskquota refer to init_lwlocks() for details */
-	RequestAddinLWLocks(4);
+	/* locks for diskquota refer to init_lwlocks() for details */
+	RequestAddinLWLocks(DiskQuotaLocksItemNumber);
 
 	/* Install startup hook to initialize our shared memory. */
 	prev_shmem_startup_hook = shmem_startup_hook;
@@ -212,6 +214,17 @@ disk_quota_shmem_startup(void)
 
 	init_shm_worker_active_tables();
 
+	memset(&hash_ctl, 0, sizeof(hash_ctl));
+	hash_ctl.keysize = sizeof(Oid);
+	hash_ctl.entrysize = sizeof(Oid);
+	hash_ctl.hash = oid_hash;
+
+	monitoring_dbid_cache = ShmemInitHash("table oid cache which shoud tracking",
+			MAX_NUM_MONITORED_DB,
+			MAX_NUM_MONITORED_DB,
+			&hash_ctl,
+			HASH_ELEM | HASH_FUNCTION);
+
 	LWLockRelease(AddinShmemInitLock);
 }
 
@@ -223,6 +236,7 @@ disk_quota_shmem_startup(void)
  * extension_ddl_message.
  * extension_ddl_lock is used to avoid concurrent diskquota
  * extension ddl(create/drop) command.
+ * monitoring_dbid_cache_lock is used to shared `monitoring_dbid_cache` on segment process.
  */
 static void
 init_lwlocks(void)
@@ -231,6 +245,7 @@ init_lwlocks(void)
 	diskquota_locks.black_map_lock = LWLockAssign();
 	diskquota_locks.extension_ddl_message_lock = LWLockAssign();
 	diskquota_locks.extension_ddl_lock = LWLockAssign();
+	diskquota_locks.monitoring_dbid_cache_lock = LWLockAssign();
 }
 
 /*
@@ -245,6 +260,7 @@ DiskQuotaShmemSize(void)
 	size = sizeof(ExtensionDDLMessage);
 	size = add_size(size, hash_estimate_size(MAX_DISK_QUOTA_BLACK_ENTRIES, sizeof(BlackMapEntry)));
 	size = add_size(size, hash_estimate_size(diskquota_max_active_tables, sizeof(DiskQuotaActiveTableEntry)));
+	size = add_size(size, hash_estimate_size(MAX_NUM_MONITORED_DB, sizeof(Oid)));
 	return size;
 }
 
@@ -394,7 +410,17 @@ do_check_diskquota_state_is_ready(void)
 	int			ret;
 	TupleDesc	tupdesc;
 	int			i;
-
+	StringInfoData sql_command;
+
+	/* Add the dbid to watching list, so the hook can catch the table change*/
+	initStringInfo(&sql_command);
+	appendStringInfo(&sql_command, "select gp_segment_id, diskquota.update_diskquota_db_list(%u, 0) from gp_dist_random('gp_id');",
+				MyDatabaseId);
+	ret = SPI_execute(sql_command.data, true, 0);
+        if (ret != SPI_OK_SELECT)
+                ereport(ERROR, (errcode(ERRCODE_INTERNAL_ERROR),
+                                                errmsg("[diskquota] check diskquota state SPI_execute failed: error code %d", ret)));
+	pfree(sql_command.data);
 	/*
 	 * check diskquota state from table diskquota.state errors will be catch
 	 * at upper level function.
@@ -433,6 +459,7 @@ do_check_diskquota_state_is_ready(void)
 	}
 	ereport(WARNING, (errmsg("Diskquota is not in ready state. "
 							 "please run UDF init_table_size_table()")));
+
 	return false;
 }
 
diff --git a/sql/test_manytable.sql b/sql/test_manytable.sql
new file mode 100644
index 00000000..eb90225f
--- /dev/null
+++ b/sql/test_manytable.sql
@@ -0,0 +1,29 @@
+-- start_ignore
+\! gpconfig -c diskquota.max_active_tables -v 2 > /dev/null
+-- end_ignore
+\! echo $?
+
+CREATE DATABASE test_manytable01;
+CREATE DATABASE test_manytable02;
+
+\c test_manytable01
+
+CREATE TABLE a01(i int) DISTRIBUTED BY (i);
+CREATE TABLE a02(i int) DISTRIBUTED BY (i);
+CREATE TABLE a03(i int) DISTRIBUTED BY (i);
+
+INSERT INTO a01 values(generate_series(0, 500));
+INSERT INTO a02 values(generate_series(0, 500));
+INSERT INTO a03 values(generate_series(0, 500));
+
+\c test_manytable02
+CREATE TABLE b01(i int) DISTRIBUTED BY (i);
+INSERT INTO b01 values(generate_series(0, 500));
+
+\c postgres
+DROP DATABASE test_manytable01;
+DROP DATABASE test_manytable02;
+
+-- start_ignore
+\! gpconfig -c diskquota.max_active_tables -v 1024 > /dev/null
+-- end_ignore
diff --git a/sql/test_table_size.sql b/sql/test_table_size.sql
index 80279cb1..aad12e83 100644
--- a/sql/test_table_size.sql
+++ b/sql/test_table_size.sql
@@ -7,7 +7,7 @@ insert into a select * from generate_series(1,10000);
 select pg_sleep(2);
 create table buffer(oid oid, relname name, size bigint);
 
-with size as ( select oid,relname,pg_total_relation_size(oid) from pg_class) insert into buffer select size.oid, size.relname, size.pg_total_relation_size  from size, diskquota.table_size as dt where dt.tableid = size.oid and relname = 'a';
+insert into buffer select oid, relname, pg_total_relation_size(oid) from pg_class, diskquota.table_size as dt where dt.size = oid and relname = 'a';
 
 insert into buffer select oid, relname, sum(pg_total_relation_size(oid)) from gp_dist_random('pg_class') where oid > 16384 and (relkind='r' or relkind='m') and relname = 'a' group by oid, relname;