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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: Pine.GSO.4.10.10008032023500.25089-100000@sappho.ics.forth.gr (view raw or flat)
Thread:
Lists: pgsql-sql
Hello,
 
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
Painter.id and a BTree index on paints.id1. However when I create a 
Btree index on Painter.id and a BTree index on paints.id1 performance
gets worst.


thank you in advance for your help
 
Sofia Alexaki
alexaki(at)ics(dot)forth(dot)gr


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pgsql-sql by date

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Subject: Re: Extracting data by months
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