From: Tom Lane <tgl@sss.pgh.pa.us>
To: Yavuz Selim Sertoglu <yavuzselim.sertoglu@medyasoft.com.tr>
cc: "pgsql-performance@lists.postgresql.org"
 <pgsql-performance@lists.postgresql.org>
Subject: Re: Gained %20 performance after disabling bitmapscan
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Comments: In-reply-to Yavuz Selim Sertoglu
 <yavuzselim.sertoglu@medyasoft.com.tr>
	message dated "Fri, 19 Oct 2018 07:19:12 -0000"
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Date: Fri, 19 Oct 2018 09:52:04 -0400
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Yavuz Selim Sertoglu <yavuzselim.sertoglu@medyasoft.com.tr> writes:
> I have a problem with my query. Query always using parallel bitmap heap =
scan.

Have you messed with the parallel cost parameters?  It seems a bit
surprising that this query wants to use parallelism at all.

>         Index Cond: (((mukellef_id)::text =3D '0123456789'::text) AND (k=
ayit_tarihi >=3D '2018-01-01 00:00:00'::timestamp without time zone) AND (=
sube_no =3D '-13'::integer) AND ((defter)::text =3D 'sm'::text))

If that's your normal query pattern, then this isn't a very good
index design:

>     Column    |            Type             |  Definition
> --------------+-----------------------------+--------------
>  mukellef_id  | character varying(12)       | mukellef_id
>  kayit_tarihi | timestamp without time zone | kayit_tarihi
>  sube_no      | integer                     | sube_no
>  defter       | character varying(4)        | defter
>  id           | bigint                      | id

The column order should be mukellef_id, sube_no, defter, kayit_tarihi, id
so that the index entries you want are adjacent in the index.

Of course, if you have other queries using this index, you might need
to leave it as-is --- but this is the query you're complaining about...

			regards, tom lane