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#Journaling

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Global journaling records all global update operations performed on a database, and used in conjunction with backup makes it possible to restore a database to its state immediately before a failure or crash.

While backup is the cornerstone of physical recovery, it is not the complete answer. Restoring a database from backup does not recover global updates made since that backup, which may have been created a number of hours before the point at which physical integrity was lost. These post-backup updates can be restored to the database from journal files after the database is restored from backup, bringing the database up to date. Any transactions open at the time of the failure are rolled back to ensure transaction integrity.

Documentation.

What is Journaling?

Journaling is a critical IRIS feature and a part of what makes IRIS a reliable database. While journaling is fundamental to IRIS, there are nuances, so I wrote this article to summarize (more briefly than our documentation which has all the details) what you need to know. I realize the irony of saying the 27 minute read is brief.

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Article
· Nov 24, 2023 4m read
Journal File Indexer

Hi community!

In this article, I'm excited to introduce my latest application, Journal File Indexer. The development of this application is rooted in the portal idea DPI-I-270.

In short, this application lets you load and index a log file in a database.

Why?

If you've ever used the log file search function in the management portal, you may have encountered a timeout error or even a blank page. This problem usually occurs when searching a large journal file. Journal File Indexer solves this problem by considerably increasing the speed of searches once the file has been loaded into the database.

Another problem arises during the restoration process. When searching for global entries in a log file to restore old or new values, the management portal doesn't have this specific functionality. A routine must therefore be coded to achieve this. Journal File Indexer comes to the rescue, incorporating a restore function!

Open Exchange app
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InterSystems FAQ rubric

If the system does not stop for 24 hours, old journal files will be deleted at 0:30 according to the "Journal file deletion settings".

A possible cause of journal files remaining that are older than the "Journal file deletion settings" is that there are transactions that remain open.

In that case, you will be able to delete the journal file by searching for processes executing transactions and finalizing the transactions.

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Recently I needed to restore a version of a production class, which was overwritten by compilation and running UpdateProduction. As the correct version was unavailable in the source control, I used journals to restore the data. Journals store a plethora of information about what's happening in the system and are quite a powerful tool. This article explains how to work with journals to extract the data you require.

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