As data is added or deleted repeatedly, the data storage efficiency becomes poor, which has an adverse effect on data retrieval performance. To avoid this, tables should be reorganized periodically with the pdrorg command (database reorganization utility). The following figure provides an overview of table reorganization processing.

Figure 13-1 Overview of table reorganization processing

Explanation

• The table data is copied into an unload data file; this is called table data unloading. The data is then stored back into the table; this is called reloading. This entire process is called table reorganization.
• If an index is defined for the table, the index information is output to an index information file when the data is reloaded. HiRDB uses that information to create the index in the batch mode, thus also reorganizing the index.