6.12.1 Determining the size of the master log file

Event log data is output to the master log file. Because event log data is output continuously while the HADB server is running, the size of the master log file will increase over time. However, the size of the master log file will be automatically reduced if both of the following conditions are met during operation of the HADB server:

• The size of the master log file exceeds 2 MB

• An update transaction is committed while there are no other pending update transactions

When the HADB server is restarted, the event log data that was output the last time the HADB server was running is deleted from the master log file.

Important

If there is insufficient free space on the disk where the master log file is created, issues such as an inability to commit or recover a transaction resulting in abnormal termination of the HADB server might occur. Therefore, take care to estimate the size required for the master log file accurately, and make sure that enough disk space is allocated.

Use the following formula to determine the size of the master log file.

Tip

Determine the estimation period that appears in the explanation of the variables based on one of the following:

• The time period during which the HADB server is running

• The time period after which the master log file is automatically reduced in size

For example, if the HADB server is stopped once every six months for server maintenance or other reasons, use six months as the estimation period. If a scenario in which the master log file can be automatically reduced in size occurs every day, use one day as the estimation period.

Formula (kilobytes)

Explanation of variables

tran_count

Number of times update transactions are executed during the estimation period

arcdir_remove_count

Number of times the files in the archive directory are deleted during the estimation period

Substitute the number of times an archive directory is deleted by executing a relevant SQL statement or command is executed for an archivable multi-chunk table. The following table shows the number of times an archive directory is deleted.

Table 6‒21: Number of times an archive directory is deleted

No.	SQL statement or command to be executed	Number of times an archive directory is deleted
1	DROP SCHEMA statement REVOKE statement with SCHEMA specified	Substitute the number of archivable multi-chunk tables that exist in the schema to be deleted.
2	ALTER TABLE statement (when executed to change an archivable multi-chunk table to a regular multi-chunk table) DROP TABLE statement TRUNCATE TABLE statement	Substitute 1.
3	PURGE CHUNK statement	Substitute the number of chunks to be deleted.
4	adbunarchivechunk command	Substitute the number of chunks to be processed.

utlexec_count

Number of times commands are executed during the estimation period

This is the sum total of the number of times the following commands are executed:

• adbimport command

• adbidxrebuild command

• adbmodarea command

• adbmergechunk command

• adbgetcst command

• adbchgchunkcomment command

• adbchgchunkstatus command

• adbarchivechunk command

• adbunarchivechunk command

• adbreorgsystemdata command

• adbsyndict command

UTi

Number of database-updating threads for each command that is executed during the estimation period

Use the following formula to determine the number of database-updating threads for each command.

• Formula (when the adbimport command is executed)

• Formula (when the adbidxrebuild command is executed)

• Formula (when the adbmodarea command is executed)

• Formula (when the adbmergechunk command is executed)

• Formula (when the adbgetcst command is executed)

• Formula (when the adbchgchunkcomment command is executed)

• Formula (when the adbchgchunkstatus command is executed)

• Formula (when the adbarchivechunk command is executed)

• Formula (when the adbunarchivechunk command is executed)

• Formula (when the adbreorgsystemdata command is executed)

• Formula (when the adbsyndict command is executed)

Note

For details about each of these commands, see the manual HADB Command Reference.

To Page Top