The following is the procedure for setting automatic extension.

Procedure

1. Modify the HiRDB system definition if necessary.
   Use the pd_rdarea_extension_timing operand to specify automatic extension triggers. For details about automatic extension triggers, see 15.8.1(2) Automatic extension triggers.
   Use the pd_rdarea_expand_format operand to specify whether to initialize the HiRDB file system area to be expanded during automatic extension. For details about initialization, see (2) Initializing a HiRDB file system area to be expanded during automatic extension.
   For details about how to modify the HiRDB system definition, see 9.1 Modifying HiRDB system definitions or 9.2 Modifying HiRDB system definitions while HiRDB is running (system reconfiguration command).
   
2. If you use the pdfmkfs command to create a HiRDB file system area, specify the -a option. During this process, we recommend that you specify the -i option to initialize the HiRDB file system area.
3. When you create an RDAREA, specify an extended segment count in the utility's control statement^#.

#

This can be specified in the CREATE RDAREA, EXPAND RDAREA, INITIALIZE RDAREA, or ALTER RDAREA statement of the database initialization utility, database structure modification utility, or registry facility initialization utility.

When a HiRDB file system area of an RDAREA to which automatic extension is applied is created in a regular file, that HiRDB file system area might become a sparse file in some cases. A sparse file is a file that has areas that are not assigned to data blocks, and only the areas that are written in the file are assigned. In this case, because no HiRDB file system area is secured in advance, when deferred write processing is used to write data to a disk, a disk space shortage might occur. If a disk space shortage occurs during RDAREA automatic extension, an error shutdown occurs in the RDAREA. In this case, if the setting that initializes the HiRDB file system area during automatic extension is used (if Y is specified for the pd_rdarea_expand_format operand in the system common definition), no error shutdown of RDAREA occurs. However, because input/output operations occur during the initialization process, processing of the following transactions might take longer:

• The transaction that updates the segment being initialized
• The transaction that is assigned a new segment by automatic extension

Therefore, we recommend that you do not initialize the HiRDB file system area (default value). We do recommend that you initialize the HiRDB system area for the case described in When size cannot be monitored under 15.8.1(4) Applying RDAREA automatic extension.

If the HiRDB file system area is to be initialized during automatic extension, determine the extended segment count, taking into consideration the fact that a delay will occur.