Thanks, that makes things clearer. But how big is big? I don't plan on my app being hugely popular, but would thousands of entries be ok? Is there an area where LIKE starts to be really slow?
On Mar 13, 11:06 am, Charles Johnson <[email protected]> wrote: > On Fri, Mar 13, 2009 at 12:42 PM, Mike C <[email protected]> wrote: > > > I've heard that using LIKE is very slow, but I see it being used a lot > > in examples, blogs etc. Is it really that bad? Since Rails doesn't > > directly support Fulltext search, this is the easiest way to get > > searching done, right? Or are there any other easier ways? I'm using > > acts_as_indexed right now, but it still doesn't do what LIKE does. > > The problem with the sql "LIKE" is that it can render the use of an > index impossible. Imagine a search like: > > @users = User.find(:all, :conditions => "first_name like '%ILL%'") > > The database will have to find BILL, GILL, JILL, JILLIAN, etc. If you have a > few hundred or a few thousand users that may not be such an issue. Millions > of users makes this a different issue altogether. A full table scan is > needed, and what will you do with all those rows? > > The point is this, when you are tempted to use LIKE be sure the data set > searched and returned are small and that you try to other ways to constrain > the search. > > Cheers-- > > Charles --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
