PRAGMA is way to set various SQLite options that will either take permanent affect or only the current connection.

cache_size

This option determines the size of the memory cache SQLite may use. The value of this option is represented by pages, each page is roughly equivalent to 1.5K of memory. By default cache_size is set to 2000 (~2.86 megabytes).

count_changes

Whether or not to count the number of affected rows after each operation. Turning it off may give a slight performance boost, however it will effectively disable sqlite_changes(). This option is disabled by default.

If you want to make the setting permanent, rather the a session setting, you need to prefix default_ to the option name.