softwareheritage=> select count(*) from origin_visit inner join origin on origin_visit.origin = origin.id where origin.type = 'hg';
 count
--------
 126678
(1 row)
softwareheritage=> select count(*) from origin o inner join origin_visit ov on o.id=ov.origin where type='hg' and url like '%googlecode%' and ov.snapshot_id = 16;  # empty snapshot
 count
--------
 126661
(1 row)

softwareheritage=> select count(*) from origin o inner join origin_visit ov on o.id=ov.origin where type='hg' and url like '%googlecode%' and ov.snapshot_id is null;  # nothing in unforeseen case
 count
-------
    17
(1 row)
softwareheritage=> begin;
BEGIN


softwareheritage=> explain delete from origin_visit where origin in (select id from origin where type='hg' and url like '%googlecode%');
                                             QUERY PLAN
-----------------------------------------------------------------------------------------------------
 Delete on origin_visit  (cost=1.26..84678.70 rows=24 width=12)
   ->  Nested Loop  (cost=1.26..84678.70 rows=24 width=12)
         ->  Index Scan using origin_type_url_idx on origin  (cost=0.69..84184.18 rows=9 width=14)
               Index Cond: (type = 'hg'::text)
               Filter: (url ~~ '%googlecode%'::text)
         ->  Index Scan using origin_visit_pkey on origin_visit  (cost=0.57..54.69 rows=26 width=14)
               Index Cond: (origin = origin.id)
(7 rows)

softwareheritage=> delete from origin_visit where origin in (select id from origin where type='hg' and url like '%googlecode%');
DELETE 126678

softwareheritage=> commit;
COMMIT