Trying to import a CSV file with 30 columns and 1400 rows but I'm repeatedly seeing PHP memory errors even though I'm allocating 256MB to PHP (run my own dedicated server) and have even upped it to as much as 2GB with no luck.

Fatal error: Out of memory (allocated 451674112) (tried to allocate 41074841 bytes) in /usr/local/www/apache22/data/includes/database.mysql-common.inc on line 41

Usually if one runs into memory busting of this magnitude, there's a problem in the code. I've seen similar errors before in PHP but the reported numbers make no sense. How can PHP report having 451,674,112 bytes allocated when the php.ini limit is set at 256MB?