Minimum Compression Factor

Compression can provide significant storage savings and improves the performance of queries that scan large volumes of data. However, it introduces additional overhead for DML operations.

As a result, table compression is generally recommended only when the resulting storage savings are deemed worthwhile. One way to control this is by specifying a minimum required compression factor. If compressing a table does not achieve a factor less than or equal to the specified value, the table is not considered eligible for compression.

You can specify a minimum required compression factor using the cfactor field of the compression command-line option. This field accepts an integer value in the range 1 to 100. It represents the percentage compression computed as:

((storage used by compressed table)/(storage used by uncompressed table)) * 100	 

For example, a compression factor of 30 (30%) indicates that the compressed table requires approximately 1/3 of the storage space needed by the uncompressed table.

The default value for cfactor is 70 (i.e. 70%).