thank you all for the useful information =D On Wed, Jun 20, 2012 at 1:39 PM, Alan Hodgson <ahodg...@simkin.ca> wrote:
> On Wednesday, June 20, 2012 01:10:03 PM Sam Z J wrote: > > 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? > > > > Indexing helps not at all. If the search string starts with a wildcard you > will always get a sequential scan of the whole table. > > Look at the full text search documentation for a better approach. > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- Zhongshi (Sam) Jiang sammyjiang...@gmail.com
