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Category: Administration

Switching Object Schemas

Published 2018-09-24 by Kevin Feasel

Steve Jones show you a quick way of switching a database object’s schema:

I haven’t had the need to move an object from one schema to another in years. Really since SQL Server 2000. I wrote about deleting a user that owns a schema recently, but that’s often a first step. The next thing I might need to do is actually move objects from that schema to a new one.

I actually ran across this command when I was looking how to move the schema to a new user. There’s actually a parameter for ALTER SCHEMA that will move objects.

This doesn’t pop up too often for me at least, but it’s good to remember if you’re using schemas as a method of categorizing data.

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Thoughts On Max Memory Settings

Published 2018-09-24 by Kevin Feasel

Monica Rathbun shares some thoughts on SQL Server’s max memory settings:

Quite often I see database administrators set SQL Server max server memory thinking everything related to SQL Server uses this shared memory pool. This is a mistake. There are many things that rely on memory that are not part of SQL Server. Best practices state that you should leave memory allotted for the operating system. However, did you know that if you are running services like SSIS, SSAS or SSRS on the same server as the database engine that it does not use the same memory you have allocated for SQL Server? If the Max Memory setting is not configured correctly, these other serves could incur memory pressure.  While the memory consumed by SSAS and SSRS can be configured, SSIS can be a little bit more challenging. Beyond this, there are even scenarios where SQL Server max memory consumed can exceed the setting, like with CLR in versions earlier than 2012 and some other bugs in SQL Server.

As a consultant, I have seen memory pressure and memory exhausted too many times to count because the DBA was unaware of this. I applaud those that take the time to properly configure this setting according to what the database engine requires. Let’s take it a step further and take the time to look at what additional services you are using and allot memory accordingly.

Read on for more.

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Undeleting A Deleted Azure SQL Database

Published 2018-09-24 by Kevin Feasel

Arun Sirpal shows us the “undoing a big mistake” button:

Okay honestly I have done this once. I have deleted Azure SQL Databases and then try and find the quickest way to recover. The Azure portal is actually pretty good when it comes to deleting resources, for example it will usually ask you to re-type the name of the resource to confirm deletion, so you can tell what a bad mistake I made.

Let’s look at how to delete a database then recover it.

I’m curious how long it stays there before dropping off into the abyss.

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Sending SQL Server Notifications To Slack

Published 2018-09-21 by Kevin Feasel

Alessandro Alpi shows how to integrate SQL Server notifications with Slack:

Now, how can we send notifications from SQL Server in an easier way than using custom code or a Slack incoming webhook? Is there any integration or a Slack app?  Yes. And guess what? I think you’ll like it because you don’t need to write a single line of code, and you don’t need to choose between CLR, PowerShell or any other language. It’s ironic, but the integration is called “Email”.

Speaking of CLR, I’ve had success with the SqlServerSlackAPI in the past.

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Running SQL Server On Cluster Shared Volumes

Published 2018-09-21 by Kevin Feasel

Sreekanth Bandarla continues a series on clustered shared volumes:

In the previous part of this series, we have seen what a cluster shared volume is and what are the advantages and other considerations to keep in mind when deploying CSVs for SQL Server workloads. In this article, I will walk though actual installation of a failover cluster Instance leveraging CSVs.

To begin with, I will walk you through my cluster setup from 20,000 foot view. I created two brand new VMs running windows server 2012 R2 and renamed them accordingly. Nothing special w.r.t disk drives at this point, Just basic VMs with a system drive(C$).

The rest of the story is over at SQLShack.

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New(ish) VLF Status: 4

Published 2018-09-20 by Kevin Feasel

Paul Randal points out a new VLF status which can appear if you’re using an Availability Group:

At least since I started working on the SQL Server team (just after 7.0 shipped) and since then there have only been two VLF status codes:

  • 0 = the VLF is not active (i.e. it can be (re)activated and overwritten)
  • (1 = not used and no-one seems to remember what it used to mean)
  • 2 = the VLF is active because at least one log record in it is ‘required’ by SQL Server for some reason (e.g. hasn’t been backed up by a log backup or scanned by replication)

A few weeks ago I learned about a new VLF status code that was added back in SQL Server 2012 but hasn’t come to light until recently (at least I’ve never encountered it in the wild). I went back-and-forth with a friend from Microsoft (Sean Gallardy, a PFE and MCM down in Tampa) who was able to dig around in the code to figure out when it’s used.

Read on to uncover the mysteries of the VLF status of 4.

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What sys.dm_exec_query_stats Can Miss

Published 2018-09-19 by Kevin Feasel

Matthew McGiffen takes us through a scenario where sys.dm_exec_query_stats did not give a complete view of what was running on SQL Server:

I got less than 50 rows back so figured I had everything covered, but the total elapsed time across all the queries was less than ten minutes, I knew the server hadn’t been rebooted for about a month so potentially that could be as little as 20 seconds of query execution a night. Even if the full 10 minutes was from the last 24 hours that still didn’t account for the long run times.

So, I convinced myself it wasn’t the queries and started looking at other things they could check. It was a long list. Lots of theories revolved around the idea that something else was running on the host at the same time.

Click through for the rest of the story.

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Forcing MAXDOP In Azure SQL DB

Published 2018-09-17 by Kevin Feasel

Arun Sirpal shows us that you can change MAXDOP in Azure SQL Database:

In this quick post I will show you my parallel plan and how I use MAXDOP = 1 to suppress parallel plan generation so the operation will be executed serially. (Disclaimer – I am not saying this is the right thing to do, merely using it as an example of tweaking this setting, to be honest in 10 years I have changed MAXDOP = 1 twice). I executed a query in Azure. You can see the classic operators such as gather streams and repartition streams.

This change will affect all queries hitting that database, so it’s a coarser tool than changing cost threshold for parallelism (not allowed) or setting MAXDOP per-query (allowed).

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Comparing Instance Configurations With sys.configurations

Published 2018-09-17 by Kevin Feasel

Jana Sattainathan has a script to compare two SQL Server instances’ configuration settings:

Steps:

1. Create a Linked Server to 2nd instance on 1st Instance
2. Create an empty table to hold the comparison data
3. Insert the 1st instance sys.configurations data into the table
4. Insert the 2nd instance sys.configurations data into the table using Linked Server
5. Compare to get the differences
6. Cleanup – Drop Linked Server and the temporary comparison table

Click through for the script.

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Table Swaps With Triggers

Published 2018-09-12 by Kevin Feasel

Jay Robinson walks through the process of making a breaking change to a large, active table with limited downtime:

I can only recall one time in the past several years (at least a decade) that I’ve found triggers to be useful. It involves data migration.

The problem: You have a massive, high-activity table. Let’s call this Table_A. You need to make significant changes to it. For example, the clustered index needs to change. How do you accomplish this?

I’ve used a similar process with good success in the past.

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