Can you point me at some? Because I've tried a few immutable data stores and been disappointed every time. Given about 10 GB of JSON structures, I keep finding things that can't outperform the boring combo of:

* Convert the versioned data to tab-separated values

* COPY it into Postgres every time

* Hope Postgres can act immutable enough even though it wasn't designed to be

The closest I've come to improving this situation was Kyoto Cabinet (unusable license) and rolling my own damn hashtable (it worked okay but adding new kinds of indexes was just unmaintainable, there's a reason databases should be made by experts).

(Disclaimer - I work at pachyderm)

http://pachyderm.io

Pachyderm is git for data. We work hard to make sure we can store data of different types (binary, text, json) efficiently. We also work hard to give you good mechanisms to read the data in a distributed way. I'd be curious how this suits your purposes.

Just started looking at Pachyderm.

While I can see how a git-based filesystem can help with some use cases, does it do any kind of indexing at all? I see that the FAQ recommends exporting the data from Pachyderm into PostgreSQL, which leaves me where I am now.

I was curious about Camlistore and Tahoe-LAFS at one point. I didn't investigate them very thoroughly, however. How do they compare?

Which ones are you thinking of?

The nice thing about git is that it doesn't really require much of the server. I run my own "git hosting" with linode, apt-get, and ssh.

Most of the solutions for immutable big data don't have that level of convenience, as far as I know. Anything which requires a lot of sysadmin and ops work will eventually become a commercial cloud service... git on the other hand is useful by itself, and good companies can obviously be built on top of it as well.

Most binary formats don't diff well.

No not really. CVS and git are basically the same thing but git is a lot better in many ways. I don't know if noms is really the git for data but those other tools are more like CVS in this analogy: clunky and slow.

They are so different it's hard to know what you mean by "basically the same thing"

Yes there are significant differences in terms of feature, implementation, etc but they have the same goal: manage source code versions.

That's how Git is used but I think that by design, it is foremost a userlevel append-only content-addressable file system.

The difference between this and a version control system is a major part of why the UI is so awful.