When a table is updated, its indexes are also updated to maintain database conformity. When an index has been defined, the following items must be evaluated:
- Items to be evaluated
- The number of times index update processing is executed increases proportionally to the number of indexes defined for the table, resulting in a commensurate increase in the SQL processing time.
- When an index is updated, update information is collected in the system log file. Therefore, if the number of indexes increases, the amount of data to be output to the system log file also increases commensurately.
- If a shortage occurs in an index page for storing updated key values, an index page split occurs. When index page split occurs, system log information on the split is collected, thereby increasing the amount of data to be stored in the system log file.
- Information to be collected
- Index statistical information is collected by the statistics analysis utility.
- Organization of this section
- (1) Splits count (SP_NM)