The Distribution Database and AGs

Andy Mallon looks at a wrinkle Availability Groups adds to replication:

This has always worked super, and has been a go-to query for me for years. But when looking at a SQL Server 2017 distributor with the distribution database in an Availability Group, that wasn’t working. All the publications had a publisher_id of 1, but in sys.servers, server_id 1 was some random linked server, and definitely not the publisher. But replication was working great. Maybe replication was set up on the other AG replica, and server_id 1 came from there.

Nope. On the other replica, it was the same story. Server_id 1 was a random linked server, and nothing to do with replication at all, let alone the publisher. But replication was working perfectly. A teammate fooling around with it in dev confirmed that if he updated the publisher_id to match the server_id we thought it should join to, replication stopped working. So, that publisher_id of 1 was correct. Or special. But also definitely different than what I’ve seen in prior versions of SQL Server.

Read on to see what Andy learned.