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

Re: Automatic optimization of IN clauses via INNER JOIN

From: Craig Ringer <craig(at)postnewspapers(dot)com(dot)au>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Thomas Hamilton <thomashamilton76(at)yahoo(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Automatic optimization of IN clauses via INNER JOIN
Date: 2009-12-18 02:20:14
Message-ID: 4B2AE6DE.206@postnewspapers.com.au (view raw or flat)
Thread:
Lists: pgsql-performance
On 17/12/2009 11:57 PM, Tom Lane wrote:
> Thomas Hamilton<thomashamilton76(at)yahoo(dot)com>  writes:
>> But in our testing under the same optimization and conditions INNER JOIN is significantly outperforming IN.
>
> [ shrug... ]  You haven't provided any details, so it's impossible to
> offer any useful advice.

In other words: can we discuss this with reference to a specific case? 
Please provide your queries, your EXPLAIN ANALYZE output, and other 
relevant details as per:

   http://wiki.postgresql.org/wiki/SlowQueryQuestions

I'd be interested in knowing whether the planner can perform such 
transformations and if so why it doesn't myself. I have the vague 
feeling there may be semantic differences in the handling of NULL but I 
can't currently seem to puzzle them out.

--
Craig Ringer

In response to

Responses

pgsql-performance by date

Next:From: Tom LaneDate: 2009-12-18 06:27:11
Subject: Re: seq scan instead of index scan
Previous:From: Scott MarloweDate: 2009-12-18 01:37:36
Subject: Re: seq scan instead of index scan

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