WITH query_1 as
(
select a, a||'_francs', clock_timestamp() from generate_series(1,5000000) a
)
insert into test_array(name) select array_agg(col1) from (select row_to_json(c) as col1 from query_1 c ) d ;

francs=> with query_1 as
francs-> (
francs(> select a, a||'_francs', clock_timestamp() from generate_series(1,5000000) a
francs(> )
francs-> insert into test_array(name) select array_agg(col1) from (select row_to_json(c) as col1 from query_1 c ) d ;
INSERT 0 1

francs=> /dt+ test_array
          List of relations
Schema |  Name  | Type | Owner | Size | Description
--------+------------+-------+--------+-------+-------------
francs | test_array | table | francs | 66 MB |
(1 row)