Re: DELETE performance problem

On Wed, Nov 25, 2009 at 4:13 PM, Luca Tettamanti <kronos(dot)it(at)gmail(dot)com>wrote:

>
>
> DELETE FROM t1 WHERE EXISTS (SELECT 1 FROM t2 WHERE t1.annotation_id =
> t2.annotation_id)
>
> performs event better:
>
> Seq Scan on t1 (cost=0.00..170388415.89 rows=22937406 width=6) (actual
> time=272.625..561241.294 rows=26185953 loops=1)
> Filter: (subplan)
> SubPlan
> -> Index Scan using t2_idx on t2 (cost=0.00..1113.63 rows=301
> width=0) (actual time=0.008..0.008 rows=1 loops=45874812)
> Index Cond: ($0 = annotation_id)
> Total runtime: 629426.014 ms
> (6 rows)
>
> Have you tried:
DELETE FROM t1 USING t2 WHERE t1.annotation_id = t2.annotation_id;

?

--
GJ