On Fri, 5 Nov 2004 10:32:43 -0500, Allen Landsidel <alandsidel@xxxxxxxxx> wrote: > On Fri, 05 Nov 2004 10:07:38 -0500, Rod Taylor <pg@xxxxxx> wrote: > > > > > It seems to me that a query saying "SELECT column FROM table WHERE > > > column LIKE 'AA%';" should be just as fast or very close to the first > > > case up above. However, explain tells me that this query is not using > > > the index above, which is what's not making sense to me. > > > > It looks for an exact expression match, and doesn't know about values > > which are equal. > > > > You can provide both clauses. > > > > WHERE column LIKE 'A%' and column LIKE 'AA%'; > > I see. That's not really optimal either however as you can probably > see already.. adding AB, AC, AD...AZ is likely to be pretty bogus and > at the least is time consuming. I see now that you mean to add that to the SELECT clause and not the index, my mistake. > Perhaps.. SELECT column FROM (SELECT column FROM table WHERE column > LIKE 'A%') AS sq WHERE column LIKE 'AA%'; > > The query planner thinks this will be pretty fast indeed, and does use > the index I am after. This was indeed pretty fast. About 7 seconds, as was modifying the WHERE as suggested above. -Allen
