I have a bunch of client point of sale (POS) systems that periodically send new sales data to one centralized database, which stores the data into one big database for repor
Just add a ini_set('memory_limit', '-1'); line at the top of your web page.
ini_set('memory_limit', '-1');
And you can set your memory as per your need in the place of -1, to 16M, etc..
16M