From: | Teodor Sigaev <teodor(at)sigaev(dot)ru> |
---|---|
To: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> |
Cc: | Rob Imig <rimig88(at)gmail(dot)com>, "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Performant queries on table with many boolean columns |
Date: | 2016-04-21 10:04:13 |
Message-ID: | 5718A59D.4090706@sigaev.ru |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
> looks like a deal for contrib/bloom index in upcoming 9.6 release
> Curious, it doesn't look like it will work with booleans out of the box.
> http://www.postgresql.org/docs/devel/static/bloom.html
There is no rocket science here:
# create table x (v bool);
# create index i on x using bloom ((v::int4));
# set enable_seqscan=off; --because of empty table
# explain select * from x where v::int4 = 1;
QUERY PLAN
------------------------------------------------------------------
Bitmap Heap Scan on x (cost=25.08..35.67 rows=14 width=1)
Recheck Cond: ((v)::integer = 1)
-> Bitmap Index Scan on i (cost=0.00..25.07 rows=14 width=0)
Index Cond: ((v)::integer = 1)
Or cast it to "char" type (with quoting!)
--
Teodor Sigaev E-mail: teodor(at)sigaev(dot)ru
WWW: http://www.sigaev.ru/
From | Date | Subject | |
---|---|---|---|
Next Message | David G. Johnston | 2016-04-21 16:12:49 | Re: Performant queries on table with many boolean columns |
Previous Message | Sven Kerkling | 2016-04-21 09:49:54 | Performance problems with postgres and null Values? |