Table spaces A database is organized into parts called table spaces. A table space is a place to store tables. When creating a table, you can decide to have certain objects such as indexes and large object (LOB) data kept separately from the rest of the table data. A table space can also be spread over one or more physical storage devices. Table spaces reside in database partition groups. Table space definitions and attributes are recorded in the database system catalog. Containers are assigned to table spaces. A container is an allocation of physical storage (such as a file or a device). A table space can be either system managed space (SMS), or database managed space (DMS). For an SMS table space, each container is a directory in the file space of the operating system, and the operating system’s file manager controls the storage space. For a DMS table space, each container is either a fixed-size pre-allocated file, or a physical device such as a disk, and the database manager controls the storage space. The page size of the table space must match the buffer pool page size. The default user table space is called USERSPACE1. Any user-created tables that are not specifically defined to an existing table space will default to this table space. Always specify a user-defined table space when creating user tables and indexes to avoid having them created in USERSPACE1. The system catalog tables exist in a regular table space called SYSCATSPACE. There is also a default system temporary table space called TEMPSPACE1, which is used to store internal temporary data required during SQL operations such as sorting, reorganizing tables, creating indexes, and joining tables. Tables containing long field data or large object data, such as multimedia objects, exist in large table spaces or in regular table spaces. The base column data for these columns is stored in a regular table space, and the long field or large object data can be stored in the same regular table space or in a specified large table space. Figure 2-2 on page 25 displays the different type of table spaces that might exist within a database.
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Performance Tuning for Content Manager