Question

Simple question I can’t seem to find the answer to.

I’m trying to squeeze some more performance out of this large app and I’m wondering if switching all of the mysql_fetch_array() function calls to only use MYSQL_ASSOC will make any difference.
It seems like it would since it’s creating an array with just:

$row['field1'] = 'field1-value';

instead of both numeric and associative keys for the same field:

$row[0] = 'field1-value';
$row['field1'] = 'field1-value';

Answer 1

There are two concepts prevalent in this scenario, which you must consider:-

1. It is always helpful to use the associative indices of “MYSQL_ASSOC” / “MYSQL_BOTH“, instead of just using the numerical indices, because the order of the fields may change in the lifetime of the website. If you understand & agree with this point, then you can use the “MYSQL_ASSOC” result type, instead of the “MYSQL_BOTH” result type.

2. If you are concerned about how much memory is being used for queries that return large result sets, then you can use “mysql_free_result()” function. More details of this function can be found here. However, all the associated result memory is automatically freed at the end of the script’s execution.

Now, coming back to your question, I think that from a performance point of view, using “MYSQL_ASSOC” result type may result in saving a little bit of memory of the server (where the website has been hosted, when the relevant web page is being executed by the PHP Parser), but you must also ensure & understand the above points as well.

Hope it helps.