Object storage databases

The object storage databases are a set of Db2® databases containing two types of data:

Descriptive information about objects
Actual data for the objects stored at the Db2 sublevel of the OAM storage hierarchy

Each Object storage group has an object storage database.

Each object storage database contains tables for an object directory and object storage. The object directory table contains descriptive information about each object. Object storage tables contain the objects. A separate table space exists for each table. Each database has three required tables:

An object directory table (contains descriptive information about objects)
A 4 KB table (contains the data for small objects)
A 32 KB table (contains the data for larger objects up to 256M)

LOB support requires the LOB storage structure in addition to the three tables mentioned above. The new structure stores object data that is greater than 32 KB or 32640 bytes for storage groups that are LOB enabled. The LOB storage structure consists of two tables:

A LOB base table (resembles the 32 KB table with the addition of a ROWID column and changing the OTOBJ column datatype from 'long varchar' to BLOB.
A LOB auxiliary table (contains the actual BLOB object represented by the OTOBJ column in the LOB base table).

Note: Reference to the LOB storage structure refers to both the LOB base table and the LOB auxiliary table.

OAM uses multiple object storage databases, each containing the three tables mentioned above. Table 1 shows the tables and table space names.

Table 1. Object storage database naming conventions
Database Name — hlq
Table Name	Table Space Name	Contents
hlq.OSM_OBJ_DIR	OSMDTS	Object directory
hlq.OSM_04 KB_OBJ_TBL	OSMOTS04	Small objects
hlq.OSM_32 KB_OBJ_TBL	OSMOTS32	Large objects (LOB support enabled)
hlq.OSM_LOB_BASE_TBL	OSMLBTS	LOB base table
hlq.OSM_LOB_AUX_TBL	OTLOBAX1	Large objects (LOB support enabled)

Sample programs that define these databases and tables are shipped with OAM. You must update these programs to meet the requirements of your installation before they are run.

The tables defined by the storage administrator will not be used by OAM unless they are related to an Object storage group through the services of ISMF. This relationship results in the definition of the DASD level of the OAM hierarchy for the specified Object storage group, and the object directory for all levels of the object storage hierarchy in that storage group. (See Figure 1.)

The object directory table from each three-table set contains an entry for each object stored in an Object storage group. The object itself might exist in one of the object storage tables on DASD or it might exist on optical disk or tape.

Table indexes are necessary for performance. Within an Object storage group, the directory table has three indexes, and each object storage table has a single index. All indexes are unique. Indexes are searched in ascending sequence (ASC).

Note: You must calculate the space required for the indexes separately because it is not included in the directory and object field sizes outlined in each table.

For the sample jobs CBRIALC0 and CBRISQL0, see Sample library members.

Figure 1. Object Storage Group Database Structure