Skip site navigation (1) Skip section navigation (2)

sequential scans on few columns tables

From: Tomasz Myrta <jasiek(at)klaster(dot)net>
To: pgsql-performance(at)postgresql(dot)org
Subject: sequential scans on few columns tables
Date: 2003-06-16 19:49:40
Message-ID: 3EEE1F54.3030507@klaster.net (view raw or flat)
Thread:
Lists: pgsql-performance
Hi
Recently I was wondering about tables difficult to index. Example - 
queries with "ilike" where clauses. Without additional contrib modules 
the only way to search such tables is sequential scan (am I right?)

The point is too keep these tables as small as possible. We can do this 
by denormalizing tables. Let's say we have table "users" which we split 
into 1:1 relation "users_header" and "users_data". We put searchable 
columns into users_header and rest of them into users_data. users_data 
have some integer foreign key referencing to users_header.

What do you think about it? Does the Postgres use advantages of small 
table users_header? Sequential scan on memory cached table should speed 
up queries, the rest columns are in integer-indexed table which 
shouldn't slow it down.

These example above is ony an idea, I don't have currently any example 
for it.

Regards,
Tomasz Myrta


Responses

pgsql-performance by date

Next:From: Bruno Wolff IIIDate: 2003-06-16 19:55:51
Subject: Re: sequential scans on few columns tables
Previous:From: Bruno Wolff IIIDate: 2003-06-16 17:58:48
Subject: Re: functional indexes instead of regular index on field(s)?

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group