Re: [HACKERS] psql nested queries with 2000+ records

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От Bruce Momjian
Тема Re: [HACKERS] psql nested queries with 2000+ records
Дата
Msg-id 199803220317.WAA01526@candle.pha.pa.us
обсуждение исходный текст
Ответ на Re: [HACKERS] psql nested queries with 2000+ records  (Coronach <coronach@hill-b-073.resnet.purdue.edu>)
Ответы Re: [HACKERS] psql nested queries with 2000+ records  (Coronach <coronach@hill-b-073.resnet.purdue.edu>)
Список pgsql-hackers
What does this show in explain?  Does it use an index?

    select name from games where mfr = ''

>
> At 09:54 AM 3/21/98 -0500, Bruce Momjian wrote:
>
> >Try it without the LIKE, with just an equals.
>
> amusements=> explain select name from games where name in (select name from
> game
> s where mfr = '');
> NOTICE:  QUERY PLAN:
>
> Seq Scan on games  (cost=207.95 size=446 width=12)
>   SubPlan
>     ->  Seq Scan on games  (cost=207.95 size=1 width=12)
>
> EXPLAIN

I ran this test:

    test=> explain select * from pg_proc where oid in (select oid from
    pg_proc where oid =3);
    NOTICE:  QUERY PLAN:

    Seq Scan on pg_proc  (cost=48.90 size=91 width=122)
      SubPlan
        ->  Index Scan on pg_proc  (cost=2.05 size=1 width=4)

and it used the index in the subquery.  Please let us about the above
test.


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