Firebird Index key size calculator

Maximum index key size is 252 bytes (for Firebird <= 1.5) or 1/4 of page size (Firebird 2). So trying to create a composite index using multiple columns might end with a:

"key size too big for index ..."

or

"key size exceeds implementation restriction for index..." errors.

Here is a tool that can help you to determine the real size of your index: Index key size calculator. Here is a backup link (Firebird index key size calculator)

TIP: Please be sure your application can access the "firebird.msg" file in order to be able to get the specific error message. Otherwise you will get a generic exception message.