OPTIMIZERINFORMATION 
The system table SYSINFO.OPTIMIZERINFORMATION contains information about value distributions that is determined by the UPDATE STATISTICS statement or read from system table FILES. The information in system table OPTIMIZERINFORMATION is used by the SQL Optimizer.
Structure
SCHEMANAME |
CHAR(32) |
Name of the schema of the table |
TABLENAME |
CHAR(32) |
Name of the table |
COLUMNNAME |
CHAR(32) |
Name of a single, non-indexed column |
INDEXNAME |
CHAR(32) |
Name of the index |
DISTINCTVALUECOUNT |
FIXED(10) |
Number of distinct values in column, index, or primary key |
CALCULATEDSIZE |
FIXED(10) |
Memory requirements of (primary key) index calculated by last UPDATE STATISTICS (KB) |
For tables and columns the value DISTINCTVALUECOUNT is determined or updated executing the UPDATE STATISTICS statement. For indexes the value DISTINCTVALUECOUNT is read from system table FILES.
The database system administrator is allowed to get information from the system table OPTIMIZERINFORMATION for all database users.
More Information
SQL Reference Manual, UPDATE STATISTICS Statement (update_statistics_statement), EXPLAIN Statement (explain_statement)
Concepts of the Database System, SQL Optimizer
Database Administration in CCMS, SQL Optimizer in CCMS, Scheduling Updates of the SQL Optimizer Statistics