Trimming unused area memory

Database Administration

Maintaining and Monitoring Your Database : Maintaining Database Structure : Area numbers : Trimming unused area memory

If you know that you will never need to add areas beyond your current maximum area number while the database is online, you can trim the area array with the -maxAreas server startup parameter. Trimming the area array saves memory within the server process. For a complete description of the -maxAreas syntax, see Maximumarea number (-maxAreas).

If you have a database with the following structure description file, trimming the area array with -maxAreas 2000 results in the allocation of a smaller area array:

#
b . f 1024
b .
#
d "Schema Area":6,32;64 .
#
#
d "First user data area":7,32;64 . f 4096
d "First user data area":7,32;64 .
#
.
.
.
#
d "Last user data area":2000,32;64 . f 4096
d "Last user data area":2000,32;64 .
#

The following figure shows the layout of areas array in memory for a database created from this structure file, and trimmed by including -maxAreas 2000 on the server startup.

Figure 43. Area array trimmed by -maxAreas startup parameter

Setting -maxAreas equal to your largest area number leaves no room for potential growth beyond that area number. You can save unused memory, and provide room for growth, by setting -maxAreas slightly higher than your maximum area number.

If during the time your database is online, you need to add areas beyond the current maximum area number specified by -maxAreas, you must shutdown and restart your database. Your options are:

Shutdown your database and restart with a larger -maxAreas setting.

Shutdown your database and remove the -maxAreas parameter from the startup command. This will allow the maximum area number, 32,000.