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. A storage area with
uniform page format is a file that is divided into groups of n
pages, called clumps, where n equals the buffer size divided
by the page size. Both buffer size and page size are user
specified values. By default, the buffer size is 6 blocks,
and the page size is 1024 bytes or 2 blocks long, resulting
in clumps of three pages. The PAGE FORMAT IS UNIFORM argument
creates a storage area file that is divided into clumps. A set
of clumps forms a logical area that can contain rows from a
single table or index only.
Uniform page format storage areas generally give the best
performance if the tables in the storage area are likely to be
subject to a wide range of queries.
o The PAGE FORMAT IS MIXED argument creates a storage area with
a format that allows rows from more than one table to reside
on or near a particular page of the storage area 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 input/output 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.
For more information on the relative advantages and disadvantages
of uniform and mixed storage areas, see the Oracle Rdb Guide to
Database Maintenance.