When a table from which optimizing information has been collected is modified, or when the related index definitions are modified, a parameter file that contains optimized information that was created before the definition modification might become unusable. When a parameter file that contains optimized information cannot be used, optimizing information can no longer be restored, and optimizing information can no longer be registered using the parameter file that contains optimized information. Therefore, you must delete the saved parameter file that contains optimized information.

The following table describes definition modification, and shows whether it is possible to use a parameter file that contains optimized information that was created before the definition modification.

Table 19-1 Description of definition modification and whether it is possible to use a parameter file that contains optimized information created before the definition modification

Targeted resource	Definition modification description	Can the parameter file that contains optimized information be used?	Remarks
Table	Table deletion (DROP TABLE)	N	None
	Table name modification (ALTER TABLE)	Y	If the pdgetcst command is to be executed, you must specify the post-modification table identifier for the -t option.
Column	Column addition (ALTER TABLE)	Y	None
	Column deletion (ALTER TABLE)	N	None
	Column attribute modification (ALTER TABLE)	Y	None
	Column name modification (ALTER TABLE)	E	Can be used if the pre-modification column name in the parameter file that contains optimized information is corrected to the post-modification column name.
Index	Index addition (CREATE INDEX) Primary key addition (ALTER TABLE)	N	None
	Index deletion (DROP INDEX) Primary key deletion (ALTER TABLE)	N	None
	Index name modification (ALTER INDEX)	E	Can be used if the pre-modification index name in the parameter file that contains optimized information is corrected to the post-modification index name.

Legend:

Y: Can be used.

E: Can be used if the content is edited.

N: An error occurs if the parameter file that contains optimized information also contains information on the deleted table or index. In all other cases, no error will occur if the parameter file is used, but search performance might decrease.