Re: [Koha-devel] query optimization

[paul POULAIN]

Chris Cormack wrote:
> On Tue, 2002-05-14 at 21:28, paul POULAIN wrote:
> > Many queries are build with :
> > (title like '$key[0]%' or title like '% $key[0]%')
> > I was wondering why :
> > * title like '$key%' is index optimizable
> > * title like '% $key%' is NOT index optimizable.
> > optimizable OR not optimizable === NOT optimizable.
> > So the resulting query is not optimizable.
> > So, what's the interest of such a string, as "title like '%'.$key.'%'" 
> > has the same result ?
> >   
> If title like '%'.$key.'%'" does the same thing and is optimisable then
> we should use that.
NO query containing "like %something" may be optimized.   This one is not
optimizable.
> What the above is trying to do is find the word if its at the start of
> the title, or is another word thats part of the title.
> For eg if we are searching for 'host'
> we want it to find titles such as 'Host of stuff' and 'Here come the
> hosts'
> We dont want to find 'ghosts'  Ie we only want wildcarding off the end
> of each word. Not the front.
> I hope this makes sense.
OK, good explanation. My construct can't differentiate  this.
> If your above construct can do this, that would be great :)
Forget my proposal.