Enabling RavenDB’s revisions allows you to ask RavenDB to keep immutable copies of a document. We originally envisioned this feature as a way to have easy audit trails and a time travel feature. Revisions were meant to be something that you’ll typically access as the administrator, not something that we expected to be used in normal course of events.
Usage in the field showed that users often want to make revisions a core part of the domain model. We have a user that uses revisions to mark the Approved (and thus, locked) version of a Plan document, for example. Another example is a payroll processing system where the Contract for a particular employee isn’t pointing to a document, but to a specific revision of that contract. Modifications to the contract have no impact on the employee unless they are explicitly moved to a new version of the contract.
Seeing all those use cases popping up for revisions, we added more features around revisions to make it easier to work with them (such as allowing to explicitly create a revision on command or enforcing revisions policies after the fact).
In RavenDB 5.3 we have added the ability to include revisions as part of the query, so you get the same benefit of reduction in the number of remote calls as you get when working with document references. Let’s say that I want to calculate payroll for a set of employees, here is how I can do that (the Contract property contains the change vector of the specific version of the contract):
In terms of API, this is how you use it:
This smooths out a scenario where you had to deal with making multiple remote calls into a single one for the whole process. Just the kind of improvement that I like to see.
More posts in "RavenDB 5.3 New Features" series:
- (26 Nov 2021) Revisions includes
- (25 Nov 2021) JSON Patch
- (24 Nov 2021) Studio & Query improvements
- (23 Nov 2021) TCP Compression
- (18 Nov 2021) Experimental PostgreSQL wire protocol
- (17 Nov 2021) Elasticsearch ETL
- (15 Nov 2021) Incremental time series & implementing lambda based accounting
- (12 Nov 2021) Incremental time series
- (11 Nov 2021) Concurrent Subscriptions & Serial operations
- (10 Nov 2021) Concurrent subscriptions