Re: Bitmap Heap Scan takes a lot of time

On 23 avr, 14:12, st...@enterprisedb.com (Gregory Stark) wrote:
> <mate...@siteduzero.com> writes:
> > This is the result of an EXPLAIN:
> >...
> > I suppose that the problem comes from the Bitmap Heap Scan which costs
> > a lot, but I can't be totally sure.
>
> > Any idea on where I should be investigating ?
>
> Try posting an EXPLAIN ANALYZE which will actually run the query and include
> information to compare against the estimates.
>
> --
>   Gregory Stark
>   EnterpriseDB          http://www.enterprisedb.com
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Thanks for your answer. Here is the EXPLAIN ANALYZE of this query:


Limit  (cost=392.43..392.43 rows=1 width=4) (actual
time=689.016..689.017 rows=1 loops=1)"
  ->  Sort  (cost=392.22..392.43 rows=83 width=4) (actual
time=688.552..688.811 rows=1000 loops=1)"
        Sort Key: flg_rid"
        ->  Index Scan using prj_frm_flg_pkey on prj_frm_flg
(cost=0.00..389.58 rows=83 width=4) (actual time=0.186..687.578
rows=1000 loops=1)"
              Index Cond: (flg_mid = 3)"
              Filter: ((NOT flg_fav) AND (NOT flg_notif) AND (NOT
flg_post))"
Total runtime: 689.092 ms"