In IBM jargon (as long as UDB is concerned), a block is referred to as
a page. The following information are some abstracts from the
Administration (Planning) document of UDB.
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By default, table data is stored on 4 KB pages. Each page (regardless
of page size) contains 68 bytes of overhead for the database manager.
This leaves 4028 bytes to hold user data (or rows), although no row on
a 4 KB page can exceed 4005 bytes in length. A row will not span
multiple pages.
Rows are usually inserted into a table in first-fit order. The file is
searched (using a free space map) for the first available space that is
large enough to hold the new row. When a row is updated, it is updated
in place, unless there is insufficient space left on the page to
contain it. If this is the case, a record is created in the original
row location that points to the new location in the table file of the
updated row.
If the ALTER TABLE APPEND ON statement is invoked, data is always
appended, and information about any free space on the data pages is not
kept.
There is a maximum of only 255 rows per page.
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I don't know whether this answers your query or not, but I suggest in
order to dig further, you refer to the UDB documentation. The URL for
the same is:
http://publib.boulder.ibm.com/infoce...help/index.jsp
regards,
dotyet
