[davismwfl]

I don't think you are to this point yet, but a RDBMS under heavy write load can run into a lot of headaches too, requiring a very carefully designed schema and proper disk sub-system (lots of IOPS), plus the need to have a solid DBA to maintain it. However, non of that is a vote against moving to the RDBMS, so I do think you should seriously consider Postgres or MySQL though as it seems like a good fit.

What I would consider though is keeping your Redis up front for accepting/processing the records in real time coming in and then batching them into your RDBMS. This provides you the ability to do reporting and other analytics through the RDBMS, but utilize Redis as a buffer for the writes. It also gives you the ability to massage the data into the specific schema that best fits the usage of the data in the RDBMS, but allowing the most efficient schema coming into Redis from the POS systems. It adds complexity though so that would have to be weighed.