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)