lichtenberger

I hope you're fine

Oh, and Sirix optionally already stores a rolling merkle hash over the data.

It's first and foremost a document store / so for JSON or XML currently, that's why it's not SQL compliant. I think other query languages as JSONiq are much more tailored to this, albeit a niche of course (based on XQuery).

Regarding tamper proof audit logs not much is missing. Cryptographic hashes instead of XXH3, a commit hash chain and signed commits. Actually, I think that's a great addition with minimal changes needed.

What you can audit currently is "who changed what" for instance.

Besides, documents are split into fine granular nodes, so we have "no" upper limit besides running out of 48bit nodeKeys/node identifiers at some point maybe.

Furthermore, a (versioned, as always) path summary keeps track of all distinct paths, which is a key ingredient for the optional secondary indexes, which can index paths or paths and content among other stuff as simply indexing fields. Optionally you can also add indexes to speed up aggregate queries (which are basically column projections).

Furthermore, the whole storage can self-validate through checksums stored in parent pages up to the root as in ZFS for instance.

DeweyIDs can be optionally stored for each node, which can speed up the comparison of subtrees between revisions (in order to detect simply which changesets belong to a certain subtree without having to traverse ancestor chains). They lend themselves well for compression.

We even have importers which can identify based on heuristics minimal edit operations to import existing revisions of XML or JSON documents and to commit these with hopefully a minimal or close to minimal set of update operations, but it depends heavily on the data.

I'm working on a side-project in my spare time since the end of 2012 (before at the university) with some gaps, which is an append-only DBS with time travel capabilities using a custom storage engine based on COW tries and a (still I think) novel page versioning strategy called Sliding Snapshot. Recently I began work on pooling pages for reuse and a custom allocator for variable page sizes. Before, I had created new instances whenever a page was read from disk instead of reusing instances, so the allocation rate was really high for parallel transactions.

https://sirix.io | https://github.com/sirixdb/sirix | http://brackit.io