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efficiency of wildcards at both ends

From:	Sam Z J <sammyjiang721(at)gmail(dot)com>
To:	pgsql-general(at)postgresql(dot)org
Subject:	efficiency of wildcards at both ends
Date:	2012-06-20 17:10:03
Message-ID:	CAGeKEGbGxHVdZTmgAaYkan=c6=7cPfTKyRTbLEv2+mdfaf_HqQ@mail.gmail.com
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Hi all

I'm curious how is wildcards at both ends implemented, e.g. LIKE '%str%'
How efficient is it if that's the only search criteria against a large
table? how much does indexing the column help and roughly how much more
space is needed for the index?

if the answers are too long, please point me to the relavant text =D

thanks

--
Zhongshi (Sam) Jiang
sammyjiang721(at)gmail(dot)com

Responses

Re: efficiency of wildcards at both ends at 2012-06-20 17:20:58 from Lonni J Friedman
Re: efficiency of wildcards at both ends at 2012-06-20 17:22:41 from Andy Colson
Re: efficiency of wildcards at both ends at 2012-06-20 17:28:20 from Edson Richter
Re: efficiency of wildcards at both ends at 2012-06-20 17:39:11 from Alan Hodgson
Re: efficiency of wildcards at both ends at 2012-06-20 17:43:12 from Thomas Kellerer
Re: efficiency of wildcards at both ends at 2012-06-23 08:51:33 from Jasen Betts

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