Re: Composite index planner issues Was: Re: Constraint exclusion oddity with composite index

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Composite index planner issues Was: Re: Constraint exclusion oddity with composite index
Date: 2007-06-06 23:47:45
Message-ID: 17222.1181173665@sss.pgh.pa.us
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"Joshua D. Drake" <jd(at)commandprompt(dot)com> writes:
>> I guess where I got confused is:
>>
>> http://www.postgresql.org/docs/8.1/static/indexes-multicolumn.html
>>
>> And explicitly:
>>
>> A multicolumn B-tree index can be used with query conditions that
>> involve any subset of the index's columns, but the index is most
>> efficient when there are constraints on the leading (leftmost) columns.

> Considering the paragraph from the documentation above, should we change
> the documentation?

That statement seems perfectly accurate to me.

regards, tom lane

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