Alan Hodgson wrote on 20.06.2012 19:39:
>> 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?
>>
>
> Indexing helps not at all. If the search string starts with a wildcard you
> will always get a sequential scan of the whole table.
Not necessarily: http://www.depesz.com/2011/02/19/waiting-for-9-1-faster-likeilike/