Re: Unable to test parallel aggregate/joins in Postgres beta 2

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От Haribabu Kommi
Тема Re: Unable to test parallel aggregate/joins in Postgres beta 2
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Msg-id CAJrrPGdF7+_jOf5nHRABh754p4TakdWEXbcygN3yx3qY2xGxtw@mail.gmail.com
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Ответ на Unable to test parallel aggregate/joins in Postgres beta 2  ("Madusudanan.B.N" <b.n.madusudanan@gmail.com>)
Ответы Re: Unable to test parallel aggregate/joins in Postgres beta 2  ("Madusudanan.B.N" <b.n.madusudanan@gmail.com>)
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On Thu, Jul 14, 2016 at 11:16 PM, Madusudanan.B.N
<b.n.madusudanan@gmail.com> wrote:
>
> 3) Is there any kind of toggle to enable parallel aggregate/join feature ?
>

I am able to generate parallel plan, The parallel plan may be costly
in your query compared
to other scans, because of which it is not selecting the parallel plan.

It is possible that if the table size is very small or you are
selecting all records of the table
and etc.

postgres=# insert into test values(generate_series(1,1000000), 'Test');
INSERT 0 1000000
postgres=# explain select * from test where f1 < 9900;                                QUERY PLAN
-----------------------------------------------------------------------------Gather  (cost=1000.00..23719.93
rows=188964width=105)  Workers Planned: 2  ->  Parallel Seq Scan on test  (cost=0.00..22719.93 rows=78735 width=105)
   Filter: (f1 < 9900)
 
(4 rows)


Regards,
Hari Babu
Fujitsu Australia



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