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
You can properly fix this by changing memory_limit
on fastcgi/fpm:
$vim /etc/php5/fpm/php.ini
Change memory, like from 128 to 512, see below
; Maximum amount of memory a script may consume (128 MB)
; http://php.net/memory-limit
memory_limit = 128M
to
; Maximum amount of memory a script may consume (128 MB)
; http://php.net/memory-limit
memory_limit = 512M