It sounds like Nubank might have the biggest Datomic installation in the world (2000 servers). This is exciting news for people like me who think Datomic is the most interesting database out there. Putting more resources behind Datomic might finally allow it to go mainstream.
I was unable to bring Datomic in-house. Mainly because our organization has a huge agreement with Oracle and all our database servers are essentially "free" to teams.
So I cheated. I created some schema designs that were immutable. I added a GUID, timestamp, and a deleted flag (value of 'Y' or 'N') to tables. Basically, all selects are against views that are defined over the tables to select the tuple associated with the max(timestamp) for that tuple along with the tuple having a deleted flag value of 'N'. This means that any select only sees the most recent tuple value for a GUID if it hasn't been "deleted".
There was a little bit more hiding in there to handle dirty writes.
But this worked very well for my requirements. By really only doing inserts, I was able to do similar "point in time" looks at the db as an immutable value.
Would you be willing to have an email chat about that? I'm thinking about doing a similar strategy with our relational database and wanted to get your experiences with that.
