How to recover deleted/updated records in Informix?

In Informix, recovering deleted or updated records depends on whether you have enabled logging and have access to the necessary log files. If you have not enabled logging or the log files have been purged, the recovery options may be limited. Here are some steps you can take to attempt to recover deleted or updated records in Informix:

1. Enable Logging: Ensure that the Informix database is set up with appropriate logging. Informix provides transaction logging, which logs changes made to the database, including deletes and updates. If logging is not enabled, there will be no record of the changes, and recovery becomes challenging.

2. Identify the Affected Tables and Timeframe: Determine the tables and the timeframe when the records were deleted or updated. This information will help narrow down the scope of the recovery.

3. Check Transaction Logs: If logging is enabled, you can check the transaction logs to find the changes made to the tables during the specified timeframe. The transaction logs are typically stored in the $INFORMIXDIR/tmp directory and have filenames with ".dat" and ".idx" extensions. You can use the onstat -l command to view the logical log files.

4. Use Informix Utilities: Informix provides utilities like onbar and ontape to back up and restore data. If you have a backup of the database taken before the records were deleted or updated, you can use the restore utility to recover the data to a point before the changes were made.

5. Check Archive Logs (if available): If you have set up archiving of the transaction logs, you might find additional historical logs that could help with recovery. Archived logs are typically stored in a separate directory, and you can use the onstat -m command to view information about the archived logs.

6. Consult Database Administrators: If you are not familiar with Informix database administration, consider involving experienced Informix database administrators or support to assist with the recovery process. They might have better insights into your specific database setup and can provide guidance on recovery options.

Please note that successful recovery of deleted or updated records depends on several factors, including the database's logging settings, the availability of transaction logs and backups, and the timeframe in which the changes occurred. It's essential to have a robust backup and recovery strategy in place to mitigate the risk of data loss in the future.