Berkeley DB

Selecting a Page Size

The size of the pages used in the underlying database can be specified by calling the DB→set_pagesize function. The minimum page size is 512 bytes, and the maximum page size is 64K bytes and must be a power of two. If no page size is specified by the application, a page size is selected based on the underlying filesystem I/O block size. (A page size selected in this way has a lower limit of 512 bytes and an upper limit of 16K bytes.) There are four issues to consider when selecting a page size: overflow record sizes, locking, I/O efficiency, and recoverability.

First, the page size implicitly sets the size of an overflow record. Overflow records are key or data items that are too large to fit on a normal database page because ...