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Author: Kevin Feasel

Views Aren’t Tables

Published 2016-04-15 by Kevin Feasel

Grant Fritchey dives into the problem with nested views:

That’s a query against the XML stored in the ProductModel table. The view was created to mask the complexity of the necessary XPath code, while providing a mechanism for retrieving the data from the XML. This is a common use of views. However, when we then treat the view as a table, and join it to other tables and views, we present a problem for the optimizer. Because a view is not a table, but is instead a query, the optimizer has to resolve this query in combination with any other views or tables to arrive at an execution plan for the whole combined mess. While the optimizer is very good at what it does, because of the complexity caused by the additional unnecessary processing to figure out which parts of the view is not needed to satisfy the query, it can make poor choices. That can result in poor performance.

“Poor performance” can be an understatement.

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Azure Status Alerts

Published 2016-04-15 by Kevin Feasel

Ron Dameron has built Outlook rules for Azure status alerts:

I do have alerts set up on the Azure portal and in Application Insights to notify me when availability or performance thresholds are violated but I also need to know if there is a global or regional issue that might affect our app so that I can respond and notify the staff when appropriate. Azure status changes are reported on the Azure Status web page.

The following will describe how to use the Azure Status page RSS feeds and Outlook rules for notification if things go sideways in Microsoft Azure.

This is a good use of Outlook’s built-in RSS reader.

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DMVs

Published 2016-04-14 by Kevin Feasel

Andy Yun talks about his favorite SQL Server feature:

Much earlier in my SQL Server career, I never knew much about how SQL Server operated under the hood. I only had knowledge of the things I could do directly, but I never questioned what was really happening behind the scenes. Then I attended SQLskills IE1 training, which was a turning point in my career. Among other things, it was my first exposure & deep dive into SQL Server Internals. I became enamored with learning how things really worked under the hood and the DMVs/DMFs became one of my best friends.

This is a big part of SQL Server administration.  It boils down to asking the server where it hurts and understanding how it responds.  DMVs are extremely helpful in that regard.

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SQL Agent

Published 2016-04-14 by Kevin Feasel

Steve Jones picks his favorite SQL Server feature:

I’ve seen the platform grow and expand quite a bit. I’ve spoken on a number of topics over the years, as my jobs have changed and my emphasis has wandered. Of all the features available, however, if I have to choose one, it would be…

SQL Agent.

I’m a programmer at heart. I grew up admiring the power of computers to execute code over and over again. I appreciate the ability of computers to remember things and remind me, or to handle them on their own.

SQL Agent has quirks, but a fully-featured scheduling system integrated into the database engine is extremely powerful.

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DBCC Checking Memory-Optimized Tables

Published 2016-04-14 by Kevin Feasel

Brent Ozar shows us how to run a DBCC check against a memory-optimized table.  The answer is not trivial:

THE EASY FIX: RUN FULL NATIVE BACKUPS EVERY DAY, AND FREAK OUT WHEN THEY FAIL.

Backup failures aren’t normally a big deal, but if you use in-memory OLTP on a standalone server or a failover clustered instance, backup failures are all-out emergencies. You need to immediately find out if the backup just ran out of drive space or lost its network connection, or if you have game-over Hekaton corruption.

Note that you can’t use SAN snapshot backups here. SQL Server won’t read the In-Memory OLTP pages during a snapshot backup, which means they can still be totally corrupt.

This works fine for shops with relatively small databases, say under 500GB.

Brent also has a Connect item to fix this.  Upvote if you have memory-optimized, durable tables.

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Message Handling With Service Broker

Published 2016-04-14 by Kevin Feasel

Colleen Morrow shows how to send and receive messages using Service Broker:

If you’ve been following along in this series, you’ll have created the necessary components of the service architecture, namely the message types, contract, queues, and services.  You will also have started a conversation between your initiator and target services.  You’re finally ready to start sending and receiving messages in your Service Broker app.  Whoohoo!  Let’s get to it!

Here’s what we’ve been waiting for, and it’s a good example going through message handling.  I also hope Colleen handles poison pill messages and other Service Broker-related traps.

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Restraint

Published 2016-04-14 by Kevin Feasel

Andy Mallon comes out of left field with his favorite feature:

It’s really tempting to implement cool-sounding features. It’s really tempting to hyper-tune solutions to be the absolutely perfect, most-optimal solution. But it takes a real expert to realize when you’re over-engineering a solution.

Take a moment to appreciate your own restraint. Appreciate all the features that you didn’t implement because you didn’t have to. Be happy that you looked at the big picture and decided the best solution was the one you were able to support.

It’s definitely an interesting approach to the T-SQL Tuesday challenge, so full credit for that.

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Azure Transactional Replication

Published 2016-04-14 by Kevin Feasel

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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Change Management Template

Published 2016-04-14 by Kevin Feasel

Kendra Little walks through a fairly simple but very useful change management template:

Good Change Management makes your team smarter. When you change things a lot, things are going to break sometimes. If you’ve done a good change request, you’ll know exactly what to do when something breaks: either you’ll roll the change back, or have a Plan B to execute on. Good change requests also mean that business owners understand the risks of the changes and have approved them, and that teammates have reviewed them: good changes aren’t done in isolation.

Change Management isn’t just for IT. If you’re a developer who deploys changes to production, you need this as well.

Change management doesn’t need to be a complex endeavor.  It should, however, give you enough information to save yourself if things get crazy.

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Database Mirroring

Published 2016-04-13 by Kevin Feasel

Derik Hammer has chosen Database Mirroring as his favorite feature:

With the end of SQL Server 2005, we also will soon see the end of database mirroring. There is a new feature releasing with SQL Server 2016 called Basic Availability Groups. This is the replacement for database mirroring. The use cases and limitations will appear very similar to database mirroring but it will use the Availability Group technology. In theory this will be like a stim-pack for the database mirroring feature while leaving it available in Standard Edition. Let’s cross our fingers that the Windows Failover Cluster components don’t slow down the failovers like it did with AGs.

A bold choice, but that “available in standard edition” thing is huge for smaller organizations which can’t afford Enterprise (especially with The Licensing Changes of 2012).

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