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Category: Replication

Testing Transactional Replication

Jes Borland wraps up her series on transactional replication from an on-prem Availability Group to Azure SQL Database:

Congratulations, you’ve configured a remote distributor, configured all of your AG replicas as publishers, and configured your SQL Database as a subscriber! Now you want to ensure that transactions are replicating to the database, and that they continue to do so if there is a failover in the AG.

Read on for the two testing scenarios.

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Replication Subscriber To Azure SQL DB

Jes Borland continues her series on setting up transactional replication between an on-prem SQL Server Availability Group and Azure SQL Database:

This subscription is going to use an Azure SQL Database.

Go to the AG primary replica. (In this demo, this is SQL2014AG2.)

Expand Replication. Expand Local Publications. Right-click the publication and select New Subscription.

It turns out that this is a basic push subscription.  Jes’s post is full of screenshots, making it even easier to follow.

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Replication Publisher To Azure SQL DB

Jes Borland continues her series on transactional replication from on-prem SQL Server + Availability Groups into Azure SQL Database:

After initializing, check the Snapshot Agent and Log Reader Agent for success. (To do so, go to Replication, right-click the publication name, and select Snapshot Agent Status and Log Reader Agent Status.) I ran into problems with the Snapshot account not having high enough permissions in the databases (it needs db_owner), and then not having enough permissions on the snapshot folder (it needs Full). (This forum post, answered by Hilary Cotter, helped: https://social.msdn.microsoft.com/Forums/sqlserver/en-US/899857db-e38e-4026-a34c-2a8c2628c6fc/access-denied-to-sql-replication-snapshot-folder?forum=sqlreplication.)

Except for the final section, it’s pretty much the same as dealing with on-prem SQL Server sans Availability Groups.

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Transactional Replication To Azure SQL Database

Jes Borland has a five-part series on replicating a series of databases in an Availability Group to Azure SQL Database.  Part 1 involves planning:

There are tasks you’ll need to take care of in SQL Server, the AG, and the SQL DB before you can begin.

This blog series assumes you already have an AG set up – it won’t go through the setup of that. It also assumes you have an Azure SQL server and a SQL Database created – it won’t go through that setup either.

Ideally, the publishers, distributor, and subscribers will all be the same version and edition of SQL Server. If not, you have to configure from the highest-version server, or you will get errors.

Part 2 prepares the replication distributor:

The first step in this process is to set up the remote distributor. As I mentioned in the first blog, you do not want your distribution database on one of the AG replicas. You need to set this up on a server that is not part of the AG.

Start by logging on to the distributor server – in this demo, SQL2014demo.

Stay tuned for the remainder of the series.

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Replicating To Azure SQL DB

Jeffrey Verheul shows how to enable replication from your on-prem SQL Server up to Azure SQL DB:

Replication to another on-premise instance is easy. You just follow the steps in the wizard, it works out-of-the-box, and the chances of this process failing are small. With replicating data to an Azure SQL database it’s a bit more of a struggle. Just one single word took me a few HOURS of investigation and a lot of swearing…

The magic word is “secure.”  Read the whole thing if you’re thinking of migrating an app to use Azure SQL DB and want to minimize downtime, or if you just want that extra level of protection that having a copy of your database out of the data center can give you.

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Replication Raiserror Procedure Change

Matt Slocum documents a change to a replication stored procedure in SQL Server 2014 SP2:

I ran into this replication error the other day and I was completely stumped.
Procedure or function sp_MSreplraiserror has too many arguments specified.
 
We started getting that error message shortly after we had applied SP2 for SQL Server 2014 to a server that is a replication Publisher (source of replicated data).

We dug into the commands that were being replicated and found that there were missing rows in the table on the replication Subscriber (destination for replicated data).  Once the rows were populated the errors stopped.  However, after digging in a bit more, we found that this error has an explainable source.

Read on for Matt’s solution to the issue.

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Azure Transactional Replication

John Sterrett names transactional replication into Azure as his favorite feature:

In the field, I see a lot of people using Availability Groups to have a near real-time replica for reporting.  I talked a little bit about this above.  What isn’t mentioned here is you have to maintain a Windows Failover Cluster, Quorum, Active Directory (Unless using Windows 2016 Preview) and more. This gets you a replica that is just a copy of the database. What does this mean? You cannot change database objects like security, indexes, etc. Also, what if you don’t need the whole database(s) for reporting? If not, you can replicate only the data you truly need.

So, let’s recap here.  You only have to replicate the data that you need.  You can have different security and indexes on your reporting subscriber database(s).  The reporting subscriber database can be scaled up or down as needed based on your needs.  The reporting database can now be an Azure Database. Folks, I call this a huge win!

There’s a lot more replication love out there than I’d expect.  John promises to follow up with a guide on how to implement this, so keep an eye out for that.

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Replication

Jon Morisi loves him some replication:

Seriously though, replication has been around since the beginning and it’s not going anywhere.  I can’t think of any other feature more prolific than replication.  Name another SQL Server HA/DR technology that is as extensible as replication.  Replication has gotten a bad rap over the years mostly on anecdotal comments that it “breaks all the time” or “it takes too much time to manage”.  I’ve worked in many environments and have setup dozens and dozens of instances of log shipping, mirroring, clusters, availability groups, and replication.  From my anecdotal experience, I can tell you I’ve had more trouble with availability groups than I have with replication.  If you have a good DBA that understands replication, uses it correctly, and is provided the correct tools (read $ for hardware/infrastructure) replication works just fine.  I have setup replication in a global environment in which multiple databases, publications, subscriptions, and agents ran around the clock and without issue.

Replication is very powerful, I agree…but it still breaks.  A lot.  I’m grateful for its existence and also for the fact that I’m not the one maintaining it…

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