martinmarques

UDR has been deprecated in favor of pglogical, which is based on better code already available on PostgreSQL (and production ready... actually we are using it with customers on production systems).

There will not be any BDR release for 9.5. That has been commented may many times on the pgsql-general list.

There will most likely be a 9.6 version, but it won't run on stock postgres (you'll still need to have a patched version of postgres).

If the rest of the features BDR relies on get in for the PG 10 release, then there will be only a BDR extension which you'd have to install (no patching postgres)

Actually with two nodes, if one node goes down, you don't have a BDR cluster anymore ;-)

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.