Re: [PHP] Getting mysql_query results into an array

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 :)

Cheers,
Rob.
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