On Wed, 2007-06-13 at 13:31 -0400, Guillaume Theoret wrote: > Thanks for the response. > > On 6/13/07, Robert Cummings <robert@xxxxxxxxxxxxx> wrote: > > On Wed, 2007-06-13 at 10:36 -0400, Guillaume Theoret wrote: > > > Hi everyone, > > > > > > Can anyone recommend any good books/resources for php and mysql > > > performance management? I'm more interested in the software > > > development side (as opposed to server configuration) of things. I'm > > > looking for anything that would be good to know when working on > > > websites that get millions of hits a day. > > > > > > Also, if anyone knows of any resources/discussions that illustrate the > > > relative performance of joins vs multiple selects I'd love to check it > > > out. > > > > JOIN will almost always be faster by virtue of the query being optimized > > and doing the work within a single request. > > Really? I thought the way it worked was that when you joined 2 tables > it needed to create every row combination applicable and then apply > the where clause. In large tables wouldn't this be slower? It's these > kinds of optimizations and when the kick in, etc that I don't know > much about. That depends on the kind of join done. Generally speaking if you use the proper type of join for your needs then the DB should be faster at joining. For instance most of my joins are LEFT joins. > In our application we wrote an abstraction layer with lazy loading. > (eg: If a User has a Profile the db users table has a profile_id and > we create a ProxyProfile that only has an id and will look up its > other attributes in the db if ever needed and then replace its > reference by a full Profile object.) Because of this, so far the > entire app only has 1 join because the other select(s) will only be > done if and when they're needed. I'm certain this is faster in the > average case but I wanted to know which is generally faster in case I > later profile the code and see that in some cases the dependent item > is pretty much always loaded. For your example this sounds like the way to go. Needlessly joining data you don't need is a waste of resources. It's best to join the data only when you actually need the extra information pulled in from the additional table(s). Cheers, Rob. -- .------------------------------------------------------------. | InterJinn Application Framework - http://www.interjinn.com | :------------------------------------------------------------: | An application and templating framework for PHP. Boasting | | a powerful, scalable system for accessing system services | | such as forms, properties, sessions, and caches. InterJinn | | also provides an extremely flexible architecture for | | creating re-usable components quickly and easily. | `------------------------------------------------------------' -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
