The percentage of unused pages allocated in a segment when a table is defined is called the percentage of free pages in a segment. Free pages here refers to unused pages. Figure 15-2 provides an overview of the percentage of free pages in a segment.
Figure 15-2 Overview of percentage of free pages in a segment
To specify the percentage of free pages in a segment, use the PCTFREE operand of the CREATE TABLE definition SQL statement.
If the percentage of free pages in a segment is set to 0 for a table for which a cluster key is specified, it will not be possible to store added data close to the cluster key values. As a result, the data storage condition becomes poor and reduction in the number of data input/output operations can no longer be expected.