Tablespace Model and Migration Utility

The Oracle Applications Tablespace Model (OATM) uses twelve consolidated tablespaces^(including three system tablespaces: temporary, system and undo segments) and provides support for locally managed tablespaces. OATM was introduced in Release 11i.10. In prior 11i releases of the E-Business Suite, each product was allocated two tablespaces, one for data and one for indexes.
The Migration Utility is a menu-based PERL program and a series of sizing estimate reports that enables conversion of E-Business Suite applications schemas either in a single comprehensive migration or a phased, schema-by-schema migration. In general Oracle recommends performing a single comprehensive migration, however this requires a sufficient amount of down time and disk space. Oracle does not support partial migration of tablespaces. You must still migrate all schemas when performing a phased schema-by-schema migration.
With OATM, each database object is mapped to a tablespace based on its Input/Output characteristics, which include object size, life span, access methods and locking granularity. This model allows for easier maintenance, and reduced space usage for the E-Business Suite.
Migrating database objects to OATM provides the following benefits:

1. Fewer and more consolidated tablespaces
2. Locally Managed Tablespaces
3. Accounts for the I/O characteristics of an object
4. Reclaims space after migration
5. Real Application Cluster (RAC) Support

The advantages of OATM’s product tablespaces are best understood in terms of the tablespace model that preceded it. This model contained two tablespaces for each Oracle Applications product. One tablespace was allocated for tables and one for indexes. In this model, the standard naming convention for tablespaces contained the product’s Oracle schema name with a suffix of either “D” for “Data” tablespaces or “X” for “Index” tablespaces. For example, the tablespaces APD and APX were the default tablespaces for Oracle Payables tables and indexes, respectively.
In contrast to the previous tablespace model, OATM contains nine default tablespaces for applications objects in addition to Undo, Temp and System database tablespaces. Indexes on transaction tables are held in a separate tablespace dedicated for transaction table indexes whereas all other indexes are held in the same tablespace as the parent/base table.
All Oracle Applications product schemas now have a default tablespace set to point to the TRANSACTION_TABLES tablespace type for data objects and the TRANSACTION_INDEXES tablespace type for index objects.
^A tablespace is a database storage unit that groups related logical structures together. The database data files are stored in tablespaces.