use a different backend database

[braid-sync]

Reasons to Consider an Alternative to Datomic:

• it's not open source, and so, is a chink in the 'Braid is an open-source system' angle
• high resource usage, even for small set-ups (minimum of ~4gb of RAM)
• not making much use of datomic's key advantages (history, immutability)
• vertical scaling will cost $
• potential contributors may have more exposure with other DBs

Reasons to Keep Datomic

• closely tied to clojure ecosystem
• datalog is awesome
• not worth effort of rewriting existing code
• very flexible data model

Potential Alternatives:

Postgres

• tried and true, well known
• lots of managed hosting available

RethinkDB

• "mongo but better"
• change feed API (although other DBs have that too)
• built in scale / shard / replication management UI

CouchDb http://couchdb.apache.org/

• change feed
• replication
• still active? (given couchbase using a different core?)

Cassandra? http://cassandra.apache.org/

H2 http://www.h2database.com/html/main.html

• could be bundled as a java dependency

Other?

Factors to consider:

• ease of set-up for contributors
• overhead for small set-ups (think: 1 team of 5 people)
• performance / ability to scale
• ease of developing for (how well does API match our needs)
• ease of on-boarding new contributors
• change feed support
• full-text search performance (or perhaps just use lucene)
• managed hosting availability