Wow, that sounds like a really nice open-source company.

They offer sources, repos for both apt and yum as well as this:

> Need more help?

> Click here for pglogical's documentation.

> Click here to look at answers to some of the most frequently asked questions.

> Want to know even more? Need some help to implement pglogical? As the developers we're probably the best people in the world to help you get up and running with pglogical. We have consultants available to provide assistance, plus our unique 24/7 Production Support subscription service also covers pglogical.

That's a company I'd want to deal with. (Not using postgres at the moment, but hired Tomitribe for some minor work and the whole experience of dealing with the people who actually write and maintain stuff instead of marketing drones etc is totally awesome.)

Thanks for pointing out pglogical. I've never heard of it before, and it's exactly what we need to support online upgrade.

How does pglogical differ from PostgreSQL's built-in streaming or log-shipping replication?

PostgreSQL streaming : send disk diffs over network, raw binary, absolutely unusable if you don't have the same postgresql version on the other side Logical : send data diffs over network. Could be used for replication, but also audit or sending to different databases...

pglogical works over the logical decoding code introduced in 9.4, so instead of sending over binary changes of the data files (SR just sends a change that says change these bytes on page X -- well, not super exact, but it gives you a picture of whats done), while logical decoding will read the WAL log, decode the changes so you can apply them else were by some plugin (pglogical would serve as a plugin in this case). I think the best way to show how it would work (and this is not what pglogical does as it would be inefficient) is by writing a plugin that feeds the logical decoded changes from the WAL and builds SQL statements from them UPDATE, INSERT, DELETE, etc. You could easily apply those on any other PostgreSQL server, or maybe even some other SQL server. Very handy for online upgrades.