From: | "Nick Fankhauser" <nickf(at)ontko(dot)com> |
---|---|
To: | "Frank Bax" <fbax(at)sympatico(dot)ca> |
Cc: | "Guru\(External\)" <guru(at)indvalley(dot)com>, <pgsql-sql(at)postgresql(dot)org> |
Subject: | Re: Resources |
Date: | 2002-01-11 16:13:58 |
Message-ID: | NEBBLAAHGLEEPCGOBHDGMEOIECAA.nickf@ontko.com |
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Thread: | |
Lists: | pgsql-sql |
> I don't beleive indexes will improve SELECT using LIKE.
I wondered about that too, so I did a test using a database I'm working
with. The results indicate that it helps substantially- here is my terminal
log file:
staging=#
staging=#
staging=# explain select count(*) from actor where actor_full_name like
'A%';
NOTICE: QUERY PLAN:
Aggregate (cost=1067.72..1067.72 rows=1 width=0)
-> Seq Scan on actor (cost=0.00..1066.29 rows=572 width=0)
EXPLAIN
staging=# create index test on actor(actor_full_name);
CREATE
staging=# explain select count(*) from actor where actor_full_name like
'A%';
NOTICE: QUERY PLAN:
Aggregate (cost=577.46..577.46 rows=1 width=0)
-> Index Scan using test on actor (cost=0.00..576.03 rows=572 width=0)
EXPLAIN
staging=#
-Nick
--------------------------------------------------------------------------
Nick Fankhauser nickf(at)ontko(dot)com Phone 1.765.935.4283 Fax 1.765.962.9788
Ray Ontko & Co. Software Consulting Services http://www.ontko.com/
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