contrib/plantuner - enable PostgreSQL planner hints

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От
Oleg Bartunov
Тема
contrib/plantuner - enable PostgreSQL planner hints
Дата
Msg-id
Pine.LNX.4.64.0910062354510.6801@sn.sai.msu.ru
Список
Дерево обсуждения
contrib/plantuner - enable PostgreSQL planner hints Oleg Bartunov <oleg@sai.msu.su>
Re: contrib/plantuner - enable PostgreSQL planner hints decibel <decibel@decibel.org>
Re: [HACKERS] contrib/plantuner - enable PostgreSQL planner hints Jeff Davis <pgsql@j-davis.com>
Re: contrib/plantuner - enable PostgreSQL planner hints Greg Stark <gsstark@mit.edu>
Re: contrib/plantuner - enable PostgreSQL planner hints Christophe Pettus <xof@thebuild.com>
Re: [HACKERS] contrib/plantuner - enable PostgreSQL planner hints Hans-Juergen Schoenig -- PostgreSQL <postgres@cybertec.at>
Re: [HACKERS] contrib/plantuner - enable PostgreSQL planner hints Scott Marlowe <scott.marlowe@gmail.com>
Hi there,

this is an announcement of our new contribution module for PostgreSQL - 
Plantuner - enable planner hints
(http://www.sai.msu.su/~megera/wiki/plantuner).

Example:

=# LOAD 'plantuner';
=# create table test(id int);
=# create index id_idx on test(id);
=# create index id_idx2 on test(id);
=# \d test
      Table "public.test"
  Column |  Type   | Modifiers
--------+---------+-----------
  id     | integer |
Indexes:
     "id_idx" btree (id)
     "id_idx2" btree (id)
=# explain select id from test where id=1;
                               QUERY PLAN
-----------------------------------------------------------------------
  Bitmap Heap Scan on test  (cost=4.34..15.03 rows=12 width=4)
    Recheck Cond: (id = 1)
    ->  Bitmap Index Scan on id_idx2  (cost=0.00..4.34 rows=12 width=0)
          Index Cond: (id = 1)
(4 rows)
=# set enable_seqscan=off;
=# set plantuner.forbid_index='id_idx2';
=# explain select id from test where id=1;
                               QUERY PLAN
----------------------------------------------------------------------
  Bitmap Heap Scan on test  (cost=4.34..15.03 rows=12 width=4)
    Recheck Cond: (id = 1)
    ->  Bitmap Index Scan on id_idx  (cost=0.00..4.34 rows=12 width=0)
          Index Cond: (id = 1)
(4 rows)
=# set plantuner.forbid_index='id_idx2,id_idx';
=# explain select id from test where id=1;
                                QUERY PLAN
-------------------------------------------------------------------------
  Seq Scan on test  (cost=10000000000.00..10000000040.00 rows=12 width=4)
    Filter: (id = 1)
(2 rows)



 	Regards,
 		Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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