12.10 Specifying the suppress option
The option for omitting part of the data in a table in order to reduce the data length for storage is called the suppress option.
When the suppress option is specified, only the significant digits of the table's decimal data (excluding leading zeros) and the storage data length are stored when the data is stored.
- Organization of this section
- (1) Effects of specifying the suppress option
- (2) Criteria
- (3) Specification
- (4) Notes
(1) Effects of specifying the suppress option
The effects of specifying the suppress option are discussed as follows.
- Improved performance
- The amount of disk space that is required is reduced because the stored data is shorter than the actual data.
- Reducing the required amount of disk space results in a reduction in the input/output time for retrieval processing, such as retrieval of all entries.
(2) Criteria
The suppress option should be specified in the following cases:
- When a table contains much decimal data and there are many significant digits.
- When the table will be accessed by many retrieval applications, such as for retrieval of all entries, but few updating applications.
(3) Specification
To specify the suppress option, enter the SUPPRESS option in the CREATE TABLE definition SQL statement.
(4) Notes
- If the number of significant digits in decimal data equals the defined length or equals 1, the data is stored with a length of defined length + 1. In this case, the length of the stored data is greater than when the suppression option is not specified.
- The suppression option cannot be specified for a table with the FIX attribute.