We[0] just recently moved from Hbase to Postgres w/ Citus. Still not fully settled in, but got incredible support from the Citus team (seriously amazing guys) and things are looking much brighter than before.
On a 8 worker nodes (16 cores, 80GB ram, 3TB SSD), we're at around 20k inserts/second, while most of the selects are running at around 100ms (besides some counts and complex queries).
If you have a lot of data and know Postgres, give it a chance.
> On a 8 worker nodes (16 cores, 80GB ram, 3TB SSD), we're at around 20k inserts/second, while most of the selects are running at around 100ms (besides some counts and complex queries).
Is that 20K separate transactions or are some of the 20K inserts grouped together?
For anyone with questions about how to properly shard a table, how to fit a problem to a distribution strategy, or general questions about deployment, Citus has a Slack channel which is active and extremely welcoming. You can request an invite here: https://slack.citusdata.com/
Disclaimer: don't work there, but on the Slack and the Citus team is nothing short of awesome.
I had a look at Citus when evaluating time series databases and the documents said that work was still under way on masterless setup for faster ingestion (up to 500k metrics /sec).
https://www.youtube.com/watch?v=NVl9_6J1G60