From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jim Nasby <Jim.Nasby@BlueTreble.com>
cc: Anton Melser <melser.anton@gmail.com>, pgsql-performance@postgresql.org
Subject: Re: Plan differences
In-reply-to: <568557D6.8040905@BlueTreble.com>
References: 
 <CAKywjPoJS4hQiLTukMDUCvmaA_aJp-W11tvnu-=wnwaL0vuqQA@mail.gmail.com>
 <10594.1451574122@sss.pgh.pa.us> <568557D6.8040905@BlueTreble.com>
Comments: In-reply-to Jim Nasby <Jim.Nasby@BlueTreble.com>
 message dated "Thu, 31 Dec 2015 10:29:10 -0600"
Date: Thu, 31 Dec 2015 12:11:15 -0500
Message-ID: <14868.1451581875@sss.pgh.pa.us>
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Sender: pgsql-performance-owner@postgresql.org

Jim Nasby <Jim.Nasby@BlueTreble.com> writes:
> On 12/31/15 9:02 AM, Tom Lane wrote:
>> If you don't want to rebuild the whole database, you can create indexes to
>> support this by declaring them with COLLATE "C", or the older way is to
>> declare them with text_pattern_ops as the index opclass.

> Do you have to do anything special in the query itself for COLLATE "C" 
> to work?

No.

> I didn't realize the two methods were equivalent.

Well, they're not equivalent exactly, but indxpath.c knows that either
way produces an index that will work for LIKE.

			regards, tom lane


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