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Only modified pages go into a version data file [1]

[1] https://github.com/sudeep9/mojo/blob/main/design.md

don't you get the same benefit if you version controlled the db file with git? with git, each commit saves a diff from the previous one as a blob. the difference is that in git, in addition to the diffs, you also have to create a working copy of the db, which means you use up at least 2x the storage your system uses. in your implementation, the diff blobs are the live db, which saves you ~2x storage. is that the main benefit?

In git, each version of the database will be a full copy. The git has to perform diff i.e. scan the database file. Imagine doing commits & creating snapshots very frequently.

Have a look at https://github.com/sudeep9/mojo/blob/main/design.md#index

sorry, yes, you mention in another comment the use case of multiple readers operating on different versions of the db simultaneously. that'd be difficult to do with git for the reason you mention.

Could you achieve the same by using BTRFS to store the db file?

Yes. But you need to have such a filesystem installed at the first place.

Mojo can run on any filesystem which does not support snapshots/versions. This makes it portable not only across different fs but also across OS.

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