Re: Join Query Perfomance Issue

Thomas Zaksek <zaksek@ptt.uni-due.de> writes:
> Nested Loop Left Join  (cost=0.00..32604.48 rows=3204 width=14) (actual
> time=11.991..2223.227 rows=2950 loops=1)
>    ->  Index Scan using
> messungen_v_dat_2007_11_12_messpunkt_minute_tag_idx on
> messungen_v_dat_2007_11_12 m  (cost=0.00..5371.09 rows=3204 width=4)
> (actual time=0.152..12.385 rows=2950 loops=1)
>          Index Cond: ((ganglinientyp = 'M'::bpchar) AND (992 = minute_tag))
>    ->  Index Scan using messwerte_mv_nr_idx on messwerte_mv w
> (cost=0.00..8.49 rows=1 width=18) (actual time=0.730..0.734 rows=1
> loops=2950)
>          Index Cond: (w.nr = m.messpunkt)
>  Total runtime: 2234.143 ms
> (6 rows)

> To me this plan looks very clean and nearly optimal,

For so many rows I'm surprised it's not using a bitmap indexscan.
What PG version is this?  How big are these tables?

            regards, tom lane