In general, setting freelists to greater than 4 will not yield much additional benefit.
The initrans setting should reflect the number of concurrent transactions expected within a block.
Four is a good number for INITRANS for OLTP applications with heavy DML activity. Increasing
the INITRANS value for data warehouse applications does not improve performance. Note also
that freelists are used only for objects in non-ASSM tablespaces.
NOTE
Oracle now automatically allows up to 255 concurrent update
transactions in any data block, depending on the available space
in the block.
When you create a tablespace, you can specify a database block size for the tablespace; by
default, the tablespace will use the database block size you specify via the DB_BLOCK_SIZE
initialization parameter. If you use a non-default database block size for the tablespace, you will
need to create a cache for that block size. For example, if your database block size is 8KB and
you want to create a 4KB database block size tablespace, you must first set a value for DB_4K_
CACHE_SIZE.
To increase the database block size for the entire database, you must rebuild the entire
database and delete all the old database files. The new files can be created in the same location
as the old files, with the same size, but will be managed more efficiently by the database. The
performance savings comes from the way that Oracle manages the block header information.
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