On Wed, Jun 20, 2012 at 10:10 AM, Sam Z J <sammyjiang721@gmail.com> 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?
>
> if the answers are too long, please point me to the relavant text =D
My limited understanding is that any time you need to resort to using
wildcards, indices are never used, and you're falling back to using
the inefficient table scan.