MAX_FILL_DATA_PAGES configuration parameter

Use the MAX_FILL_DATA_PAGES configuration parameter to control inserting more rows to pages that have variable-length rows.

onconfig.std value
MAX_FILL_DATA_PAGES 0
values
0 or 1
units
Integer
takes effect
After you edit your onconfig file and restart the database server.

Usage

Set the MAX_FILL_DATA_PAGES value to 1 to allow more rows to be inserted per page in tables that have variable-length rows. This setting can reduce disk space, make more efficient use of the buffer pool, and reduce table scan times.

If MAX_FILL_DATA_PAGES is enabled, the server will add a new row to a recently modified page with existing rows if adding the row leaves at least 10 percent of the page free for future expansion of all the rows in the page. If MAX_FILL_DATA_PAGES is not set, the server will add the row only if there is sufficient room on the page to allow the new row to grow to its maximum length.

A possible disadvantage of enabling MAX_FILL_DATA_PAGES and allowing more variable-length rows per page is that the server might store rows in a different physical order. Also, as the page fills, updates made to the variable-length columns in a row could cause the row to expand so it no longer completely fits on the page. This causes the server to split the row onto two pages, increasing the access time for the row.

To take advantage of this setting, existing tables with variable-length rows must be reloaded or existing pages must be modified, followed by further inserts.


Copyright© 2019 HCL Technologies Limited