On Tue, February 13, 2007 8:22 pm, Robert Cummings wrote: > On Tue, 2007-02-13 at 18:22 -0600, Richard Lynch wrote: >> #2 >> loop through mysql result set to build $array >> perform some kind of calculation upon $array >> >> In this case, it's USUALLY much more efficient to write an SQL query >> to perform the calculation. >> >> Databases are highly optimized for this kind of thing, and very >> efficient at it. >> PHP is a generalized programming language, and not so efficient for >> this kind of task. >> >> #2 does occasionally have an exception to the rule, where the SQL >> query is nasty and the PHP is fast and easy, but that's awfully >> rare. > > I hear this all the time that the database should do as much as > possible > "it's highly optimized" yadda yadda. I'm going to go out on a limb and > say that in a heavily loaded system, shoving all the work into the > primary bottleneck is a bad idea. 100 workers make light work, and > that > would be the inherent power in horizontal scalability. Databases do > not > scale well horizontally, machines loaded with Apache and PHP do, > especially when each machine doesn't expect the database server to do > all the work. In fact, I'd wager queries involving joins are another > bane on horizontal scalability since now the tables are forced to > reside > on the same machine. > > I could be completely wrong, I've never worked on an extremely loaded > server, but I get a tick every time someone says "shove all the work > into the query", and that usually happens when something doesn't feel > right :) For the 0.1% of people who can't get enough performance out of their web farm and "single" DB, there are several interesting possibilities for factoring or distributed processing, including scaling horizontally with PHP but they also can consider segmenting the DB in various ways, or even replacing the DB with something faster/lighter or something that scales horizontally for the most-used functionality (e.g., MCache for session management). The "right" answer for that 0.1% isn't gonna be covered in a 10-second answer on PHP-General, though, as it's almost-for-sure going to depend on their application needs more than any off-the-rack answer. -- Some people have a "gift" link here. Know what I want? I want you to buy a CD from some starving artist. http://cdbaby.com/browse/from/lynch Yeah, I get a buck. So? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
