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Posted by Ivαn Sαnchez Ortega on 01/18/06 21:05
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Chung Leong wrote:
> R. Rajesh Jeba Anbiah wrote:
>>
>> As many people have pointed out, *never* dump the table data into
>> array. Fetch the record and immediately get that processed. If you have
>> any *valid* reason, buffer the data into a very very small (known)
>> sized array. If using MySQL, use the LIMIT if possible.
>
> The reasoning being?
Code refactoring, for example.
As you may already know, refactoring is almost always a good idea, as it
reduces complexity of the algorithm, procesing time, and increases the
cache hit ratio, to name a few consecuences.
Let's suppose the following example:
<?php
mysql_pconnect(blahblahblah);
$r = mysql_query(blahblahblah);
$db_results = array();
while ($row = mysql_fetch_array($r))
{
$db_results[] = $row;
}
foreach ($db_results as $row)
{
foobar;
}
?>
Well, let's refactor that code:
<?php
mysql_pconnect(blahblahblah);
$r = mysql_query(blahblahblah);
while ($row = mysql_fetch_array($r))
{
foobar;
}
?>
Less complexity, less CPU time, less memory, less code. Any developer that
has been taught anything about algorithms knows that. You'd better have a
good reason to not refactorize your code in this way.
> In my opinion conserving memory for the sake of conserving memory is
> just silly. Hardware resources are there to be used. There's nothing
> wrong with a script using a few megs of extra memory, as it'll release
> them a short time later.
That's not a bad idea for batch jobs, but is a terrible one when you have
tenths, hundreds of hits per second. A few MB of memory per script may seem
a small issue, but think about a few MB per script, 100 scripts per second.
A "short time" is not a big thing, but a "short time" hundreds of times per
second is.
- --
- ----------------------------------
IvΓ‘n SΓ‘nchez Ortega -i-punto-sanchez--arroba-mirame-punto-net
http://acm.asoc.fi.upm.es/~mr/ ; http://acm.asoc.fi.upm.es/~ivan/
MSN:i_eat_s_p_a_m_for_breakfast@hotmail.com
Jabber:ivansanchez@jabber.org ; ivansanchez@kdetalk.net
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