Syntax options:

    PAGE FORMAT IS UNIFORM | PAGE FORMAT IS MIXED

    Specifies the on-disk structure for the storage area.

    o  The default is PAGE FORMAT IS UNIFORM and creates a storage
       area data file that is divided into clumps. Clump size, which
       is derived from buffer size, is 3 pages by default. A set
       of clumps forms a logical area that can contain rows from
       a single table only. For more information on uniform page
       formats, see the Oracle Rdb7 Guide to Database Performance and
       Tuning.

       Uniform page format storage areas generally give the best
       performance if the tables in the storage area are subject to a
       wide range of queries.

    o  The PAGE FORMAT IS MIXED clause creates a storage area with
       a format that lets rows from more than one table reside on
       or near a particular page of the storage area data file. This
       is useful for storing related rows from different tables on
       the same page of the data file. For storage areas subject to
       repeated queries that retrieve those related rows, a mixed
       page format can greatly reduce I/O overhead if the mix of
       rows on the page is carefully controlled. However, mixed page
       format storage areas degrade performance if the mix of rows
       on the page is not suited for the queries made against the
       storage area.

                                   NOTE

       The main storage area created by the CREATE DATABASE
       statement, called RDB$SYSTEM, must have uniform pages. If
       you specify PAGE FORMAT IS MIXED as a default storage area
       parameter, SQL generates a warning message and overrides
       that default when it creates the RDB$SYSTEM storage area.