Add gokv.Store implementation for ArangoDB

[philippgille]

ArangoDB seems popular due to its multi-model approach, although key-value pairs are currently only implemented as documents with single values and no secondary indexes (see arangodb/arangodb#663 and https://docs.arangodb.com/3.4/Manual/Architecture/DeploymentModes/Cluster/DataModels.html#keyvalue-pairs).

• https://github.com/arangodb/arangodb
• https://godoc.org/github.com/arangodb/go-driver

[gfxlabs]

hi there! i made this for arangodb. https://github.com/gfxlabs/gokv/tree/arangodb/arangodb

not sure exactly what features you would want in it so i kept it simple . we can add index on the key for a more advanced store, but honestly if it is only key->value lookup that is being done, the K field should be removed. I copied the mongodb test suite and it seems to pass, so that's good at least.

arangodb is a bit weird in its rules for byte arrays and keys. this is explained at the top of arangodb.go. tl;dr keys need to be a subset of ascii, and there is no 1 byte numeric type (only 8).

as for connecting, it creates the database + collection on connection if they do not exist, and so it would be up to user to either use a user with permissions to do so, or to pre-populate their database.

let me know if there is anything else that would be needed, or if you have any questions.

arangodb is just a nosql database layer on top of rocksdb, so performance wise, raw rocksdb will of course always be better.

[philippgille]

Hello 👋 , Wow thank you for working on this! I had a quick look just now and it looks pretty good 👍 . You can open a PR, then I will dig into the details and maybe ask some questions around individual lines.