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A question about indexes...

From: Alexaki Sofia <alexaki(at)ics(dot)forth(dot)gr>
To: pgsql-sql(at)postgresql(dot)org
Subject: A question about indexes...
Date: 2000-08-03 17:51:44
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-sql
I have the  following tables in my db
Painter (id integer,  uri varchar(256)) and
paints (id1 integer, id2 integer)
I  want to optimize the question
   select id from Painter where uri = 'xxxxx';
 What kind of index (Btree or Hash) is more efficient to create on field
uri  since it's a string?
I also want  to optimize the join between the ables Painter and paints 
on the fields id and id1 respectively?
I can either define the field id as a Primary Key or create an Btree index
on it. What is more effient?? 
>From  my test I see that creating  Btree index is  a bit faster!!. 
Would the performance (of the join) be  improved if  I created indexes
both on field id and id1 or it's sufficient  to create one of the two
indexes ?
As far as I can see the performance is improved if I have a Primary Key on and a BTree index on paints.id1. However when I create a 
Btree index on and a BTree index on paints.id1 performance
gets worst.

thank you in advance for your help
Sofia Alexaki


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