When a table is defined, pages are not allocated. Pages are allocated as needed when data is to be stored in the table. Once a page has been allocated (once a page has been used), the page cannot be reused until it has been released.

If an index is defined, the system allocates pages according to the number of data items. If there is no data item, the system allocates only one page (root page). If you specify the EMPTY option in the CREATE INDEX statement (so as not to create the index entity), the system does not allocate any page.

Notes

1. If you update data in such a manner that the row length of a non-FIX table changes, the space created by the reduced row length cannot be reused.
2. An index page cannot be reused until a key value that is identical to a key value that was stored in the deleted page is added.
3. Reusing a page freed up by deletion of data is subject to the following restrictions:

• The page cannot be used for rows that contain a repetition column or a column whose type is VARCHAR of at least 256 bytes, BINARY type, or abstract data type.
• Until a segment's usage reaches 100%, the page cannot be used for insertion of data.
• Until a transaction that issued a DELETE has been committed, the free space generated by the deletion cannot be used.

• When a segment is released, the pages in the segment are also released.
• When a table has been locked with the LOCK statement with EXCLUSIVE specified, pages will be released when the UAP deletes all rows on the pages. The index pages are not released.
• When the PURGE TABLE statement is executed, the pages and segments of the tables and indexes are released. However, the root pages of the indexes remain.
• You release used free pages with the free page release utility (pdreclaim command). For details about releasing used free pages, see the manual HiRDB Version 8 System Operation Guide.