Subject Re: [ib-support] query optimizing
Author Helen Borrie
At 12:04 PM 05-12-00 -0500, you wrote:
>At 10:12 PM 12/5/2000 +1100, Helen Borrie wrote:
> >Yes, it should be sub-second. I think the problem is in the CONTAINING
> >clause - I always get confused about this but I *think* containing doesn't
> >use the index (or maybe CONTAINING does use it and STARTING WITH
> >doesn't).
>Helen - the way to remember is that the index can only be used from the
>beginning of the key - just as a compound index will be used if you supply
>values for the first columns defined, a partial string match will use an
>index iff the value is at the beginning of the key. Containing makes no
>such assumption. Starting with does - that's why it exists. Like can go
>either way. If the query includes a literal comparison value (Bram%) then
>it will use an index. If the query passes a variable, or if the literal
>comparison starts with a wild card, the index can not be used.

Got it!


All for Open and Open for All
InterBase Developer Initiative ยท