From: | Daniele Orlandi <daniele(at)orlandi(dot)com> |
---|---|
To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Optimizer & boolean syntax |
Date: | 2002-11-21 18:39:19 |
Message-ID: | 3DDD2857.9070102@orlandi.com |
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Thread: | |
Lists: | pgsql-hackers |
Are those two syntaxes eqivalent ?
select * from users where monitored;
select * from users where monitored=true;
If the answer is yes, the optimimer probably doesn't agree with you :)
Tested on RC1:
template1=# create table a (a boolean, b text);
CREATE TABLE
.... inserted ~18000 rows with just one true (just to make an index scan
meaningful)....
template1=# vacuum analyze a;
VACUUM
template1=# explain select * from a where a;
QUERY PLAN
----------------------------------------------------
Seq Scan on a (cost=0.00..802.64 rows=1 width=11)
Filter: a
(2 rows)
template1=# explain select * from a where a=true;
QUERY PLAN
--------------------------------------------------------------
Index Scan using a_a on a (cost=0.00..2.01 rows=1 width=11)
Index Cond: (a = true)
(2 rows)
Bye!
--
Daniele Orlandi
Planet Srl
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