diff --git a/Makefile b/Makefile
index fcccc3a..3613f58 100644
--- a/Makefile
+++ b/Makefile
@@ -11,7 +11,7 @@ PGFILEDESC = "pg_ivm - incremental view maintenance on PostgreSQL"
 EXTENSION = pg_ivm
 DATA = pg_ivm--1.0.sql
 
-REGRESS = pg_ivm create_immv
+REGRESS = pg_ivm create_immv refresh_immv
 
 PG_CONFIG = pg_config
 PGXS := $(shell $(PG_CONFIG) --pgxs)
diff --git a/createas.c b/createas.c
index 21ca067..5698ca4 100644
--- a/createas.c
+++ b/createas.c
@@ -69,7 +69,7 @@ static void check_ivm_restriction(Node *node);
 static bool check_ivm_restriction_walker(Node *node, check_ivm_restriction_context *context);
 static Bitmapset *get_primary_key_attnos_from_query(Query *query, List **constraintList, bool is_create);
 
-static void StoreImmvQuery(Oid viewOid, Query *viewQuery);
+static void StoreImmvQuery(Oid viewOid, bool ispopulated, Query *viewQuery);
 
 #if defined(PG_VERSION_NUM) && (PG_VERSION_NUM < 140000)
 static bool CreateTableAsRelExists(CreateTableAsStmt *ctas);
@@ -232,7 +232,7 @@ ExecCreateImmv(ParseState *pstate, CreateTableAsStmt *stmt,
 	}
 
 	/* Create the "view" part of an IMMV. */
-	StoreImmvQuery(address.objectId, viewQuery);
+	StoreImmvQuery(address.objectId, !into->skipData, viewQuery);
 
 	if (is_matview)
 	{
@@ -975,7 +975,7 @@ get_primary_key_attnos_from_query(Query *query, List **constraintList, bool is_c
  * Store the query for the IMMV to pg_ivwm_immv
  */
 static void
-StoreImmvQuery(Oid viewOid, Query *viewQuery)
+StoreImmvQuery(Oid viewOid, bool ispopulated, Query *viewQuery)
 {
 	char   *querytree = nodeToString((Node *) viewQuery);
 	Datum values[Natts_pg_ivm_immv];
@@ -989,6 +989,7 @@ StoreImmvQuery(Oid viewOid, Query *viewQuery)
 	memset(isNulls, false, sizeof(isNulls));
 
 	values[Anum_pg_ivm_immv_immvrelid -1 ] = ObjectIdGetDatum(viewOid);
+	values[Anum_pg_ivm_immv_ispopulated -1 ] = BoolGetDatum(ispopulated);
 	values[Anum_pg_ivm_immv_viewdef -1 ] = CStringGetTextDatum(querytree);
 
 	pgIvmImmv = table_open(PgIvmImmvRelationId(), RowExclusiveLock);
diff --git a/expected/create_immv.out b/expected/create_immv.out
index a70e96f..085cf17 100644
--- a/expected/create_immv.out
+++ b/expected/create_immv.out
@@ -41,3 +41,4 @@ SELECT immvrelid FROM pg_ivm_immv ORDER BY 1;
 -----------
 (0 rows)
 
+DROP TABLE t;
diff --git a/expected/refresh_immv.out b/expected/refresh_immv.out
new file mode 100644
index 0000000..b7add64
--- /dev/null
+++ b/expected/refresh_immv.out
@@ -0,0 +1,105 @@
+CREATE TABLE t (i int PRIMARY KEY);
+INSERT INTO t SELECT generate_series(1, 5);
+SELECT create_immv('mv', 'SELECT * FROM t');
+NOTICE:  created index "mv_index" on immv "mv"
+ create_immv 
+-------------
+           5
+(1 row)
+
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+ immvrelid | ispopulated 
+-----------+-------------
+ mv        | t
+(1 row)
+
+-- refresh immv without changing the ispopulated flag
+SELECT refresh_immv('mv', true);
+ refresh_immv 
+--------------
+            5
+(1 row)
+
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+ immvrelid | ispopulated 
+-----------+-------------
+ mv        | t
+(1 row)
+
+INSERT INTO t VALUES(6);
+SELECT i FROM mv ORDER BY 1;
+ i 
+---
+ 1
+ 2
+ 3
+ 4
+ 5
+ 6
+(6 rows)
+
+-- change ispopulated to False
+SELECT refresh_immv('mv', false);
+ refresh_immv 
+--------------
+            0
+(1 row)
+
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+ immvrelid | ispopulated 
+-----------+-------------
+ mv        | f
+(1 row)
+
+SELECT i FROM mv ORDER BY 1;
+ i 
+---
+(0 rows)
+
+-- immv remains empty
+INSERT INTO t VALUES(7);
+SELECT i FROM mv ORDER BY 1;
+ i 
+---
+(0 rows)
+
+-- chaneg ispopulated to True, immv is updated
+SELECT refresh_immv('mv', true);
+ refresh_immv 
+--------------
+            7
+(1 row)
+
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+ immvrelid | ispopulated 
+-----------+-------------
+ mv        | t
+(1 row)
+
+SELECT i FROM mv ORDER BY 1;
+ i 
+---
+ 1
+ 2
+ 3
+ 4
+ 5
+ 6
+ 7
+(7 rows)
+
+-- immediate maintenance
+INSERT INTO t VALUES(8);
+SELECT i FROM mv ORDER BY 1;
+ i 
+---
+ 1
+ 2
+ 3
+ 4
+ 5
+ 6
+ 7
+ 8
+(8 rows)
+
diff --git a/matview.c b/matview.c
index cf6f4c3..e2be9ef 100644
--- a/matview.c
+++ b/matview.c
@@ -12,8 +12,14 @@
 #include "postgres.h"
 
 #include "access/genam.h"
+#include "access/multixact.h"
 #include "access/table.h"
 #include "access/xact.h"
+#include "catalog/pg_depend.h"
+#include "catalog/heap.h"
+#include "catalog/pg_trigger.h"
+#include "commands/cluster.h"
+#include "commands/matview.h"
 #include "commands/tablecmds.h"
 #include "executor/execdesc.h"
 #include "executor/executor.h"
@@ -26,6 +32,7 @@
 #include "parser/parse_func.h"
 #include "parser/parse_relation.h"
 #include "parser/parser.h"
+#include "pgstat.h"
 #include "rewrite/rewriteHandler.h"
 #include "rewrite/rowsecurity.h"
 #include "storage/lmgr.h"
@@ -92,6 +99,7 @@ static uint64 refresh_immv_datafill(DestReceiver *dest, Query *query,
 						 TupleDesc *resultTupleDesc,
 						 const char *queryString);
 
+static void refresh_by_heap_swap(Oid matviewOid, Oid OIDNewHeap, char relpersistence);
 static void OpenImmvIncrementalMaintenance(void);
 static void CloseImmvIncrementalMaintenance(void);
 static Query *get_immv_query(Relation matviewRel);
@@ -138,6 +146,250 @@ static List *get_securityQuals(Oid relId, int rt_index, Query *query);
 PG_FUNCTION_INFO_V1(IVM_immediate_before);
 PG_FUNCTION_INFO_V1(IVM_immediate_maintenance);
 
+/*
+ * ExecRefreshImmv -- execute a refresh_immv() function
+ *
+ * This imitates PostgreSQL's ExecRefreshMatView().
+ */
+ObjectAddress
+ExecRefreshImmv(const char *relname, bool skipData, QueryCompletion *qc)
+{
+	Oid			matviewOid;
+	Relation	matviewRel;
+	Query	   *dataQuery;
+	Query	   *viewQuery;
+	Oid			tableSpace;
+	Oid			relowner;
+	Oid			OIDNewHeap;
+	DestReceiver *dest;
+	uint64		processed = 0;
+	//bool		concurrent;
+	LOCKMODE	lockmode;
+	char		relpersistence;
+	Oid			save_userid;
+	int			save_sec_context;
+	int			save_nestlevel;
+	ObjectAddress address;
+	Relation pgIvmImmv;
+	TupleDesc tupdesc;
+	ScanKeyData key;
+	SysScanDesc scan;
+	HeapTuple	tup;
+	bool isnull;
+	Datum datum;
+	bool oldSkipData;
+
+	/* Determine strength of lock needed. */
+	//concurrent = stmt->concurrent;
+	//lockmode = concurrent ? ExclusiveLock : AccessExclusiveLock;
+	lockmode = AccessExclusiveLock;
+
+	/*
+	 * Get a lock until end of transaction.
+	 */
+	matviewOid = RelnameGetRelid(relname);
+	if (!OidIsValid(matviewOid))
+	    ereport(ERROR,
+		    (errcode(ERRCODE_UNDEFINED_TABLE),
+		     errmsg("relation \"%s\" does not exist", relname)));
+
+	matviewRel = table_open(matviewOid, lockmode);
+	relowner = matviewRel->rd_rel->relowner;
+
+	/*
+	 * Switch to the owner's userid, so that any functions are run as that
+	 * user.  Also lock down security-restricted operations and arrange to
+	 * make GUC variable changes local to this command.
+	 */
+	GetUserIdAndSecContext(&save_userid, &save_sec_context);
+	SetUserIdAndSecContext(relowner,
+						   save_sec_context | SECURITY_RESTRICTED_OPERATION);
+	save_nestlevel = NewGUCNestLevel();
+
+	pgIvmImmv = table_open(PgIvmImmvRelationId(), RowExclusiveLock);
+	tupdesc = RelationGetDescr(pgIvmImmv);
+	ScanKeyInit(&key,
+			    Anum_pg_ivm_immv_immvrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(RelationGetRelid(matviewRel)));
+	scan = systable_beginscan(pgIvmImmv, PgIvmImmvPrimaryKeyIndexId(),
+								  true, NULL, 1, &key);
+	tup = systable_getnext(scan);
+	if (!HeapTupleIsValid(tup))
+	{
+		elog(ERROR, "could not find tuple for immvrelid %s", relname);
+	}
+
+	datum = heap_getattr(tup, Anum_pg_ivm_immv_ispopulated, tupdesc, &isnull);
+	Assert(!isnull);
+	oldSkipData = !DatumGetBool(datum);
+
+	/* update pg_ivm_immv view */
+	if (skipData != oldSkipData)
+	{
+		Datum values[Natts_pg_ivm_immv];
+		bool nulls[Natts_pg_ivm_immv];
+		bool replaces[Natts_pg_ivm_immv];
+		HeapTuple newtup = NULL;
+
+		memset(values, 0, sizeof(values));
+		values[Anum_pg_ivm_immv_ispopulated -1 ] = BoolGetDatum(!skipData);
+		MemSet(nulls, false, sizeof(nulls));
+		MemSet(replaces, false, sizeof(replaces));
+		replaces[Anum_pg_ivm_immv_ispopulated -1 ] = true;
+
+		newtup = heap_modify_tuple(tup, tupdesc, values, nulls, replaces);
+
+   		CatalogTupleUpdate(pgIvmImmv, &newtup->t_self, newtup);
+		heap_freetuple(newtup);
+	}
+
+	systable_endscan(scan);
+	table_close(pgIvmImmv, NoLock);
+
+	viewQuery = get_immv_query(matviewRel);
+
+	/* For IMMV, we need to rewrite matview query */
+	if (!skipData)
+		dataQuery = rewriteQueryForIMMV(viewQuery,NIL);
+
+	/*
+	 * Check for active uses of the relation in the current transaction, such
+	 * as open scans.
+	 *
+	 * NB: We count on this to protect us against problems with refreshing the
+	 * data using TABLE_INSERT_FROZEN.
+	 */
+	CheckTableNotInUse(matviewRel, "refresh an IMMV");
+
+	tableSpace = matviewRel->rd_rel->reltablespace;
+	relpersistence = matviewRel->rd_rel->relpersistence;
+
+	/* delete IMMV triggers. */
+	if (skipData)
+	{
+		Relation	tgRel;
+		Relation	depRel;
+		ScanKeyData key;
+		SysScanDesc scan;
+		HeapTuple	tup;
+		ObjectAddresses *immv_triggers;
+
+		immv_triggers = new_object_addresses();
+
+		tgRel = table_open(TriggerRelationId, RowExclusiveLock);
+		depRel = table_open(DependRelationId, RowExclusiveLock);
+
+		/* search triggers that depends on IMMV. */
+		ScanKeyInit(&key,
+					Anum_pg_depend_refobjid,
+					BTEqualStrategyNumber, F_OIDEQ,
+					ObjectIdGetDatum(matviewOid));
+		scan = systable_beginscan(depRel, DependReferenceIndexId, true,
+								  NULL, 1, &key);
+		while ((tup = systable_getnext(scan)) != NULL)
+		{
+			ObjectAddress obj;
+			Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(tup);
+
+			if (foundDep->classid == TriggerRelationId)
+			{
+				HeapTuple	tgtup;
+				ScanKeyData tgkey[1];
+				SysScanDesc tgscan;
+				Form_pg_trigger tgform;
+
+				/* Find the trigger name. */
+				ScanKeyInit(&tgkey[0],
+							Anum_pg_trigger_oid,
+							BTEqualStrategyNumber, F_OIDEQ,
+							ObjectIdGetDatum(foundDep->objid));
+
+				tgscan = systable_beginscan(tgRel, TriggerOidIndexId, true,
+											NULL, 1, tgkey);
+				tgtup = systable_getnext(tgscan);
+				if (!HeapTupleIsValid(tgtup))
+					elog(ERROR, "could not find tuple for immv trigger %u", foundDep->objid);
+
+				tgform = (Form_pg_trigger) GETSTRUCT(tgtup);
+
+				/* If trigger is created by IMMV, delete it. */
+				if (strncmp(NameStr(tgform->tgname), "IVM_trigger_", 12) == 0)
+				{
+					obj.classId = foundDep->classid;
+					obj.objectId = foundDep->objid;
+					obj.objectSubId = foundDep->refobjsubid;
+					add_exact_object_address(&obj, immv_triggers);
+				}
+				systable_endscan(tgscan);
+			}
+		}
+		systable_endscan(scan);
+
+		performMultipleDeletions(immv_triggers, DROP_RESTRICT, PERFORM_DELETION_INTERNAL);
+
+		table_close(depRel, RowExclusiveLock);
+		table_close(tgRel, RowExclusiveLock);
+		free_object_addresses(immv_triggers);
+	}
+
+	/*
+	 * Create the transient table that will receive the regenerated data. Lock
+	 * it against access by any other process until commit (by which time it
+	 * will be gone).
+	 */
+	OIDNewHeap = make_new_heap(matviewOid, tableSpace,
+							   relpersistence, ExclusiveLock);
+	LockRelationOid(OIDNewHeap, AccessExclusiveLock);
+	dest = CreateTransientRelDestReceiver(OIDNewHeap);
+
+	/* Generate the data, if wanted. */
+	if (!skipData)
+		processed = refresh_immv_datafill(dest, dataQuery, NULL, NULL, "");
+
+	/* Make the matview match the newly generated data. */
+	refresh_by_heap_swap(matviewOid, OIDNewHeap, relpersistence);
+
+	/*
+	 * Inform cumulative stats system about our activity: basically, we
+	 * truncated the matview and inserted some new data.  (The concurrent
+	 * code path above doesn't need to worry about this because the
+	 * inserts and deletes it issues get counted by lower-level code.)
+	 */
+	pgstat_count_truncate(matviewRel);
+	if (!skipData)
+		pgstat_count_heap_insert(matviewRel, processed);
+
+	if (!skipData && oldSkipData)
+	{
+		CreateIvmTriggersOnBaseTables(viewQuery, matviewOid, true);
+	}
+
+	table_close(matviewRel, NoLock);
+
+	/* Roll back any GUC changes */
+	AtEOXact_GUC(false, save_nestlevel);
+
+	/* Restore userid and security context */
+	SetUserIdAndSecContext(save_userid, save_sec_context);
+
+	ObjectAddressSet(address, RelationRelationId, matviewOid);
+
+	/*
+	 * Save the rowcount so that pg_stat_statements can track the total number
+	 * of rows processed by REFRESH MATERIALIZED VIEW command. Note that we
+	 * still don't display the rowcount in the command completion tag output,
+	 * i.e., the display_rowcount flag of CMDTAG_REFRESH_MATERIALIZED_VIEW
+	 * command tag is left false in cmdtaglist.h. Otherwise, the change of
+	 * completion tag output might break applications using it.
+	 */
+	if (qc)
+		SetQueryCompletion(qc, CMDTAG_SELECT, processed);
+
+	return address;
+}
+
+
 /*
  * refresh_immv_datafill
  *
@@ -210,6 +462,17 @@ refresh_immv_datafill(DestReceiver *dest, Query *query,
 	return processed;
 }
 
+/*
+ * Swap the physical files of the target and transient tables, then rebuild
+ * the target's indexes and throw away the transient table.  Security context
+ * swapping is handled by the called function, so it is not needed here.
+ */
+static void
+refresh_by_heap_swap(Oid matviewOid, Oid OIDNewHeap, char relpersistence)
+{
+	finish_heap_swap(matviewOid, OIDNewHeap, false, false, true, true,
+					 RecentXmin, ReadNextMultiXactId(), relpersistence);
+}
 
 /*
  * This should be used to test whether the backend is in a context where it is
diff --git a/pg_ivm--1.0.sql b/pg_ivm--1.0.sql
index 7b9c6fd..f8ed430 100644
--- a/pg_ivm--1.0.sql
+++ b/pg_ivm--1.0.sql
@@ -4,6 +4,7 @@ CREATE SCHEMA __pg_ivm__;
 
 CREATE TABLE __pg_ivm__.pg_ivm_immv(
   immvrelid regclass NOT NULL,
+  ispopulated bool NOT NULL,
   viewdef text NOT NULL,
 
   CONSTRAINT pg_ivm_immv_pkey PRIMARY KEY (immvrelid)
@@ -23,6 +24,12 @@ STRICT
 AS 'MODULE_PATHNAME', 'create_immv'
 LANGUAGE C;
 
+CREATE FUNCTION refresh_immv(text, bool)
+RETURNS bigint 
+STRICT
+AS 'MODULE_PATHNAME', 'refresh_immv'
+LANGUAGE C;
+
 -- trigger functions
 
 CREATE FUNCTION "IVM_immediate_before"()
diff --git a/pg_ivm.c b/pg_ivm.c
index ae00655..f38d049 100644
--- a/pg_ivm.c
+++ b/pg_ivm.c
@@ -44,6 +44,7 @@ static void parseNameAndColumns(const char *string, List **names, List **colName
 
 /* SQL callable functions */
 PG_FUNCTION_INFO_V1(create_immv);
+PG_FUNCTION_INFO_V1(refresh_immv);
 PG_FUNCTION_INFO_V1(IVM_prevent_immv_change);
 
 /*
@@ -227,6 +228,21 @@ IVM_prevent_immv_change(PG_FUNCTION_ARGS)
 	return PointerGetDatum(NULL);
 }
 
+/*
+ * User inerface for refreshing an IMMV
+ */
+Datum
+refresh_immv(PG_FUNCTION_ARGS)
+{
+	text	*t_relname = PG_GETARG_TEXT_PP(0);
+	bool	ispopulated = PG_GETARG_BOOL(1);
+	char	*relname = text_to_cstring(t_relname);
+	QueryCompletion qc;
+
+	ExecRefreshImmv( relname, !(ispopulated), &qc);
+
+	PG_RETURN_INT64(qc.nprocessed);
+}
 
 /*
  * Create triggers to prevent IMMV from being changed
@@ -246,7 +262,6 @@ CreateChangePreventTrigger(Oid matviewOid)
 	refaddr.objectId = matviewOid;
 	refaddr.objectSubId = 0;
 
-
 	ivm_trigger = makeNode(CreateTrigStmt);
 	ivm_trigger->relation = NULL;
 	ivm_trigger->row = false;
diff --git a/pg_ivm.h b/pg_ivm.h
index 0d3856e..9ebac58 100644
--- a/pg_ivm.h
+++ b/pg_ivm.h
@@ -19,10 +19,11 @@
 #include "tcop/dest.h"
 #include "utils/queryenvironment.h"
 
-#define Natts_pg_ivm_immv 2
+#define Natts_pg_ivm_immv 3
 
 #define Anum_pg_ivm_immv_immvrelid 1
-#define Anum_pg_ivm_immv_viewdef 2
+#define Anum_pg_ivm_immv_ispopulated 2
+#define Anum_pg_ivm_immv_viewdef 3
 
 /* pg_ivm.c */
 
@@ -41,6 +42,7 @@ extern Query *rewriteQueryForIMMV(Query *query, List *colNames);
 
 /* matview.c */
 
+extern ObjectAddress ExecRefreshImmv(const char *relname, bool skipData, QueryCompletion *qc);
 extern bool ImmvIncrementalMaintenanceIsEnabled(void);
 extern Datum IVM_immediate_before(PG_FUNCTION_ARGS);
 extern Datum IVM_immediate_maintenance(PG_FUNCTION_ARGS);
diff --git a/sql/create_immv.sql b/sql/create_immv.sql
index f5ca551..b76792d 100644
--- a/sql/create_immv.sql
+++ b/sql/create_immv.sql
@@ -15,3 +15,5 @@ SELECT immvrelid FROM pg_ivm_immv ORDER BY 1;
 
 DROP TABLE mv2;
 SELECT immvrelid FROM pg_ivm_immv ORDER BY 1;
+
+DROP TABLE t;
diff --git a/sql/refresh_immv.sql b/sql/refresh_immv.sql
new file mode 100644
index 0000000..59d7179
--- /dev/null
+++ b/sql/refresh_immv.sql
@@ -0,0 +1,31 @@
+CREATE TABLE t (i int PRIMARY KEY);
+INSERT INTO t SELECT generate_series(1, 5);
+
+SELECT create_immv('mv', 'SELECT * FROM t');
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+
+-- refresh immv without changing the ispopulated flag
+SELECT refresh_immv('mv', true);
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+
+INSERT INTO t VALUES(6);
+SELECT i FROM mv ORDER BY 1;
+
+-- change ispopulated to False
+SELECT refresh_immv('mv', false);
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+SELECT i FROM mv ORDER BY 1;
+
+-- immv remains empty
+INSERT INTO t VALUES(7);
+SELECT i FROM mv ORDER BY 1;
+
+-- chaneg ispopulated to True, immv is updated
+SELECT refresh_immv('mv', true);
+SELECT immvrelid, ispopulated FROM pg_ivm_immv ORDER BY 1;
+SELECT i FROM mv ORDER BY 1;
+
+-- immediate maintenance
+INSERT INTO t VALUES(8);
+SELECT i FROM mv ORDER BY 1;
+