[mysql] concept and performance

[thinkninja]

I was wondering whether it is better performance wise to select x rows with one query or to do select y rows x times?

I'm trying to build a forum with nested threading. Right now, the way I retrieve the nested replies is with recursive calls to the function and additional queries to get the children (WHERE parent_id = x). If there's a lot of nesting that can be a lot of queries. Also, I haven't yet implemented a way to limit the results returned (although, it's trivial). This would be easy if it were flat threading.

I thought about making parent_id a string instead of an integer, e.g. "1/3/14/21" but I don't see how that could improve performance. I'm also not sure of how to duplicate the recursive nature with a single query...or what the query would look like.

Thanks for your time.

[adrian_quah]

ninja,

try using these to see which is faster: -

<!-- put this at the top of the page -->
<?php
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$starttime = $mtime;
;?>

<!-- put other code and html in here -->

<!-- put this code at the bottom of the page -->
<?php
$mtime = microtime();
$mtime = explode(" ",$mtime);
$mtime = $mtime[1] + $mtime[0];
$endtime = $mtime;
$totaltime = ($endtime - $starttime);
echo "This page was created in ".$totaltime." seconds";
;?>

and let us know 😉

[thinkninja]

Thanks Adrian, will do 🙂