The log files are as follows:
The transaction log stores the changes made to the database since it was last backed up.
There is normally one transaction log for each backup interval. The log stores the time and the full details of each database transaction. Should data loss occur, the Database Recovery utility uses the transaction log to roll-forward the database.
If transaction logging is disabled but rollback lofgging is enabled a temporary transaction log is created using the .RLL file extension. This uses the same format file format as an ordinary transaction log but it will only contain the most recent transactions (those completed since the rollback log was last re-started).
Files with .LBK extension are backup transaction log files created by DYNABACK.
The information in the transaction log can be viewed using the Transaction Log Auditing utility, as described in Auditing the Transaction Log.
The roll-back log stores images of data before changes are made.
Whenever a change is made to the index file or to the data file, the pre-image of the record being changed is written to the roll-back file. Following a system failure, the database recovery mechanism reads the roll-back file backwards and applies its contents. This allows the data and index files to be recovered as they were at the time the roll-back file was opened.
The database is brought fully up to date and the roll-back file is deleted from time to time, and a new roll-back file is created as described in Updating the Database.
The console log records all access to DP4 programs, and also all system and fail errors.
DP4 maintains the console log in the location specified in the Directory Assignment option of DFSETUP. Each time a program is run, a record is written to the file in this format:
<user> <read/write authority> <time> <date> <program name>
You can specify separate log files for each user, by making sure each user works from a separate directory ansd leaving the location for SYSLOG.PRN blank. Alternatively, you can have a single console log for the system, by specifying a location such as c:\dp4. The latter option is usually preferable.
This is an excerpt from a console log:
255 255 13:42:09 02 Mar 2001 [MAKEDB ]. Program running without login.
255 255 13:42:14 02 Mar 2001 System error 68
DP4 System error 68. Origin: Operator error
Correct transaction log file not found.
A frequent cause of this problem is that a log file for
a previous session of the database has not been deleted.
255 255 13:42:30 02 Mar 2001 [MAKEDB ]. Program running without login.
255 255 18:19:49 02 Mar 2001 [TCPMGR ]. Program running without login.
255 255 18:20:00 02 Mar 2001 [PROGDATE]. Program running without login.
255 255 18:20:03 02 Mar 2001 [PROGDATE]. Program running without login.
255 255 18:18:37 06 Mar 2001 [IMPSETUP]. Program running without login.
255 255 10:39:55 07 Mar 2001 [COLLATE ]. Program running without login.
255 255 11:12:43 07 Mar 2001 [DFSETUP ]. Program running without login.
255 255 11:13:00 07 Mar 2001 [DP4 ]. Program running without login.
dp4 99 99 11:13:14 07 Mar 2001 DFSETUP
dp4 99 99 11:13:31 07 Mar 2001 DBCHECK
dp4 99 99 11:13:37 07 Mar 2001 %SYSTEM
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