With 4D v20 R3, a new feature has been introduced to enable better journal management. This feature concerns the “Use log file” option, which can now be overridden like other backup parameters.
In this blog post, we’ll explain why this is useful and show you how to use it.
As developers and database administrators, you know the importance of quickly recovering from data corruption. Backups and journals help you with the task. But sometimes, a backup may be corrupted, and you need to come back from an older backup and integrate multiple journals consecutively. Or maybe your journal file is growing big too quickly, and you prefer to regularly create a new one to avoid cluttering your server hard drive. Or you are just using your own way of backing up your database. In all these cases, you must integrate multiple journals, which is only manually possible through the Maintenance and Security Center.
With 4D v20, you can automatically integrate multiple journals at database startup. Let me explain to you how it works.
4D provides you with multiple built-in ways to backup your data: 4D backup and the use of a mirror server. With 4D v20, 4D exposes internal commands to lock the datastore, allowing you to copy your data while 4D is running.
First, let’s speak about the different means to backup your data with 4D.
By now, you’ve surely discovered the new ability to identify your users thanks to the SET USER ALIAS command. In 4D v18 R2, the command’s behavior has been extended. How? Keep reading!
When integrating the log file, 4D stops at the first error and doesn’t return any error message. Reasons for integration errors could be a damaged log, by example because of a bad hard disk or software error during writing. If that error happens at the end, no problem; but it could also be at the start or in the middle of the log. In this case, the data after the error might be useful.
Now, when the integration fails in standard mode, you can try integration in auto-repair mode. In this case, 4D tries to resolve the error encountered, doesn’t stop the integration, and returns the error list.
In 4D applications, the data file is important, so all the activity of the database is stored in the log file. As you all know, the log file is a vital element for the restoration of your database following an unfortunate contingency. However all the information on the database activity may also be useful for analysis. For example, to check the activity on a table, to see the changes made by a user, and to follow a record’s history.