Re: Unable to test parallel aggregate/joins in Postgres beta 2 - Mailing list pgsql-hackers

From Haribabu Kommi
Subject Re: Unable to test parallel aggregate/joins in Postgres beta 2
Date
Msg-id CAJrrPGdF7+_jOf5nHRABh754p4TakdWEXbcygN3yx3qY2xGxtw@mail.gmail.com
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In response to Unable to test parallel aggregate/joins in Postgres beta 2  ("Madusudanan.B.N" <b.n.madusudanan@gmail.com>)
Responses Re: Unable to test parallel aggregate/joins in Postgres beta 2  ("Madusudanan.B.N" <b.n.madusudanan@gmail.com>)
List pgsql-hackers
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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