page utilization percent

page utilization percent is used during page allocations to control whether SAP ASE scans a table’s object allocation map (OAM) to find unused pages or simply allocates a new extent to the table.

Summary Information
Default value	95
Range of values	1–100
Status	Dynamic
Display level	Comprehensive
Required role	System administrator
Configuration group	Disk I/O

The page utilization percent parameter is a performance optimization for servers with very large tables; it reduces the time needed to add new space.

If you set page utilization percent to 100, SAP ASE scans through all OAM pages to find unused pages allocated to the object before allocating a new extent. When this parameter is set lower than 100, SAP ASE compares the page utilization percent setting to the ratio of used and unused pages allocated to the table, as follows:

100 * used pages/(used pages + unused pages)

If page utilization percent is lower than the ratio, SAP ASE allocates a new extent instead of searching for the unused pages.

For example, when inserting data into a 10GB table that has 120 OAM pages and only 1 unused data page:

A page utilization percent of 100 tells SAP ASE to scan through all 120 OAM pages to locate an unused data page.
A page utilization percent of 95 allows SAP ASE to allocate a new extent to the object, because 95 is lower than the ratio of used pages to used and unused pages.

A low page utilization percent value results in more unused pages. A high page utilization percent value slows page allocations in very large tables, as SAP ASE performs an OAM scan to locate each unused page before allocating a new extent. This increases logical and physical I/O.

If page allocations (especially in the case of large inserts) seem to be slow, lower the value of page utilization percent, but reset it after inserting the data. A lower setting affects all tables on the server and results in unused pages in all tables.

Fast bulk copy ignores the page utilization percent setting and always allocates new extents until there are no more extents available in the database.