Re: Unsetting vars when not needed?

[Brent Baisley <brent@xxxxxxxxxxxx>]

I use mysql_free_result when I'm done with the particular query, but I 
don't really bother unsetting things unless I'm doing something that is 
using a lot of memory. PHP will clear everything at the end of the run 
anyway. I guess technically it's garbage collection, but PHP is wiping 
everything, so it doesn't have the overhead of checking what's been 
used, still in use or expired. It's just a wipe.
Unsetting is a good coding habit to get into, but I'm not sure of the 
performance benefits. There are lots of others areas I would focus on 
first to get better performance, like minimizing the number of 
connections you need to make to mysql, optimizing your queries, output 
buffering, etc.

On Nov 12, 2004, at 8:53 AM, Jordi Canals wrote:

> Hi all,
>
> I was working now in a new site developed with PHP 5.0.2 and a wonder
> came to me:
>
> Is usefull and recommended to unset a class instance when not needed?
>
> Specially when the class was instantiated inside a function and the
> function ends. In this case, the system should  automatically destroy
> the instance (as it is a local var inside a function).
>
> If we manually unset the instance at the end of the function, does
> this affect the PHP performance? I mean, will PHP have to do an extra
> job unsetting the var?
>
> Also, the same question arises with database results. Is it worth to
> call mysql_free_result at the end of a function that uses it? Must
> take into consideration that there are lots of functions that use lots
> of MySQL results.
>
> Thanks for any comment
> Jordi.
>
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Brent Baisley
Systems Architect
Landover Associates, Inc.
Search & Advisory Services for Advanced Technology Environments
p: 212.759.6400/800.759.0577

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