Sam Z J wrote on 20.06.2012 19:10:
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
Since 9.1 you can speed up such a query using a trigram index.
http://www.depesz.com/2011/02/19/waiting-for-9-1-faster-likeilike/
http://www.postgresonline.com/journal/archives/212-PostgreSQL-9.1-Trigrams-teaching-LIKE-and-ILIKE-new-tricks.html
Another option might be to use the wildspeed extension
http://www.sai.msu.su/~megera/wiki/wildspeed
(never used that myself though)
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