Posted by Ciaran on 05/10/07 16:43

On May 10, 5:05 pm, David Gillen <Bel...@RedBrick.DCU.IE> wrote:
> Ciaran said:> Hi All,
> > Is it faster to have mySql look up as much data as possible in one
> > complex query or to have php do all the complex processing and submit
> > lots of simple queries to the mysql database?
>
> It was vary. Sometime a complex multijoin query with nested sub-queries may be
> quicker, other times it will take far longer.
> Alot will depend on how your database is setup in terms of normalisation and
> indexes on tables etc.
> Without doing independent tests yourself for both cases it is impossible to
> know.
>
> D.
> --
> Fermat was right.


Hmm, What about at the most basic level. For example would it be
quicker to run:
SELECT * FROM users WHERE userID IN
(1,2,4,7,8,9,10,11,13,14,15,17,18,35,etc,etc,etc);

or select each userID seperately in a PHP foreach loop with something
like this statement:
SELECT * FROM users WHERE userID=2 LIMIT 1;

I'm basically asking: Is it contacting the database that slows down
PHP or is it the actual speed at which mySQL runs.

The former suggests that one big query would generally be quicker
while the latter suggests many basic queries would generally be
quicker.
I'm just looking for a rule of thumb here, not hard answers.

Cheers,
Ciarán

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