PHP Session Management Storage Methods
Because PHP abstracts the storage method from the programmatic interface to session management, different storage strategies can be used. PHP can be configured to store session variables in files on disk (the default method), in memory, or in a user-defined way. The method used is configured by the session.save_handler parameter in the php.ini file. Here are the values the session.save_handler parameter can be set to:
- files
-
This is the default storage method for PHP, where session variables are serialized and written to a session file.
- mm
-
The memory management storage method allows session variables to be stored in Apache's runtime memory. Using memory has the advantage of better performance than files on disk. However, if many sessions must be supported, and each session uses a large volume of data, the memory used by the Apache process may be high. To use memory to store session variables, Apache must be configured and compiled to use an installed memory management module (--with-mm).
- user
-
The user-defined method allows an application to save session variables to systems other than file or memory, such as to a table in a database. By defining several handler prototypes, PHP allows the developer to define the behavior of the low-level session management. A full explanation is given in the next section.