status of the data in a database, for example, number of data items, and base table and index DSI space
requirements.
Optimization information definition opportunity
Optimization information must be determined in an ordinary way, considering the number of records stored in a
database and variations of the index key that will occur after the definition of the storage structure is completed.
Additional opportunities for optimization information definition are listed below.
When optimization information is defined with values assumed in advance:
· When a database is defined
· When a database is reconfigured
- When a table DSI is added at split storage
- When index is added
- When a large amount of data is added or updated
Defining optimization information
Use the rdbddlex command to specify the SET STATISTICS statement to define optimization information with the
values assumed in advance. For more information on the SET STATISTICS statement, refer to the SQL Reference
Guide.
Optimization information must be defined for each table or index DSI.
Optimization information can be defined for each table or index DSO; however, the system converts the specified
value for each DSO into a value for each DSI.
Optimization information should therefore be defined for each DSI.
· Definition for each table DSI (data structure: SEQUENTIAL)
· Definition for each index DSI (data structure: BTREE)
The items to be specified depend on the definition method. Details of the optimization information to be defined are
listed below.
80