HP Integrity NonStop J-Series - Manual (Page 72)

DEVELOPING A DATA BASE
Increasing Block Size
When you determine the size of a file, estimate the number of
records that the file will store. To do this you will have to
find answers to such questions as, "How many people work for the
company?" You might want to include space for records that are
no longer active such as those that store information about
people who have left the company. Consider how many records will
be added to the file each month and leave some room for growth.
As a minimum, you will want to make the primary extent big enough
to hold all of the records that are to be initially stored in the
file. You can then let the system use the secondary extents for
growth.
Once you have determined the number of records that your file
will contain, add the following FUP statement to the FUP file-
creation commands:
SET EXT (xxx RECS, yyy RECS)
where xxx is the number of records that are to fit in the
primary extent and yyy is the number of records that are to fit
in the secondary extent. Insert this command before the FUP
CREATE commands that create the data file and the alternate key
file. The FUP SET EXT command is the only way that you can
define your file size.
When you include the SET EXT command, FUP uses the number of
records you specify, the record size, and the size of the file
block to calculate the number of pages required to hold your
data.
Refer to the ENSCRIBE Programming Manual for more information
about selecting an appropriate extent size.
Increasing Block Size
If you increase the size of the BLOCK parameter, you can enhance
the efficiency of any application that accesses records from the
file sequentially. Consider changing this parameter from BLOCK
512 to BLOCK 4096.
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