I guess I was more interested in finding out whether questDB is mature for production use.

The product is impressive, but it looks like the documentation has some way to go. This is often indicative of the maturity of the product itself.

I was very interested in the Postgres wire protocol and its usage.

This part does not seem to be very mature.

Examples:

* The documentation doesn't mention a word of the default username/password on port 8812. I had to find this on a mailing list somewhere after 10 minutes of googling. Has this been hardcoded into the code?

* If you were to connect a typical Postgres tool this port, you'd be able to do selects but not even see the tables. If using psql and doing \d I get:

  ERROR:  Invalid column: oid

Any performance metric comparisons available?

We ran this experiment Vs influx some time ago for ingestion here https://medium.com/questdb/speeding-up-influx-line-protocol-...

In terms of queries, see our previous post on HN to get a sense https://news.ycombinator.com/item?id=22803504

Ingestion rate is pretty good in Influx and we are happy with that for now. If QuestDB is better I definitely won't complain. The issues with Influx is data integrity and also the difficulty in manipulating time series data if that becomes an issue (e.g turning all "0" string values into a 0i). How does QuestDB fare in this regard?

We take data integrity very seriously. This is one of the reasons QuestDB actually exists. We haven't had reports of data corruption or loss yet. We can commit durably if needed too.

To manipulate data we support "add" and "delete" column on the fly. We can also add column replace and type change if needed. This is pretty easy to do.

PostgreSQL wire is in beta. It works with JDBC driver and we will add metadata support quite soon.