On: Migration from Postgres to Datomic

[jarym]

Conceptually that is fine but there are complications (speaking based on recent and ongoing experience on a project I'm working on):

1. When you have multiple entity tables that are inter-related, snapshotting one in isolation is not sufficient.

2. When only certain changes on certain fields should result in a new snapshot.

Granted, both of these are solvable with built-in Postgres mechanisms (and a bit of co-operation from the application server) but simple it is not.

In our case we also move historic records to a second 'history' table.

[ComodoHacker → jarym]

To add to your list, with 1. referential integrity becomes a problem. Basically you move it up the stack into the application code and lose consistency guarantees RDBMS can provide.

I'm curious wether Datomic supports RE and how.