SQL Agent’s 5 Second Rule

Ewald Cress uncovers a change in the way the SQL Agent scheduler works in SQL Server 2016 compared to prior versions:

Upon completion of a job, the next run time is calculated based on the last scheduled time plus the schedule interval. However, allowance is made for the edge cases where the completed invocation overruns into the next start time. In such a situation, there isn’t a “catch-up” run; instead, the schedule is advanced iteratively until it reaches a future point in time.

However, 2016 introduces a new twist. When applying the “is the proposed next schedule time after Now()?” check, it adds five seconds to Now(). In other words, the question becomes “Is the proposed next schedule time more than five seconds in the future?”

Ewald jumps into the debugger to understand this better, so click through for that.

Replacing SQL Agent In Azure

Bob Rubocki has some Q&A regarding automating in Azure the types of things you’d normally run SQL Agent jobs for:

Q: Is there any way to handle the execution of SSIS packages stored locally?

A: Azure Automation works on Azure resources.  It cannot be used for executing local SSIS packages.

In some cases, you may still need a scheduling tool (which might be a VM with SQL Agent).

Connecting To Linux SQL Agent Using Powershell

Slava Murygin shows how to connect to a SQL Agent running on Linux using the SqlServer Powershell module:

From this point we will work directly with SQL Server.
In order to establish connection you have to run following script.
The most important are 2nd and third lines:
– In second line you have to provide your SQL Server Instance address, by replacing “<your_server_instance>” by something like “192.168.58.11” or “192.168.58.11\MSSQLSERVER,1433”
– When second line runs it will ask you for SQL Server credentials !!! So, you have to enter SQL user name and it’s password.

Slava does note some limitations at present, but a lot of the functionality seems to be there.

PBM Schedule Failures

Dave Turpin diagnoses an issue where scheduled Policy-Based Management policy checks were failing:

While it is easy to build and test policies by executing them on demand (especially powerful when run through Central Management Server) I had some issues getting my policies to run in “on schedule” mode.

To be more specific, my policies that use the ExecuteSQL function have been an issue.  What I was finding was:

  • The policy would run fine “on demand” but…
  • When I run the policy through the PBM scheduler, the policy would fail.

Dealing with false positives is not a good start for any monitoring service, so getting to the root of the issue was critical.

Read on for the solution.

Indexing Woes

Shane O’Neill relates a tale of trying to create an index with a SQL Agent job.  Easy, right?

Now I’m angry too since I count these failures as personal and I don’t like failing, so I get cracking on the investigation.
Straight away, that error message doesn’t help my mood.
I’m not indexing a view!
I’m not including computed columns!
It’s not a filtered index!
The columns are not xml data types, or spatial operations!
And nowhere, nowhere am I using double quotes to justify needing to set QUOTED_IDENTIFIER on!

SO WTF SQL SERVER, WHY ARE YOU GIVING ME THESE ERRORS???

Read the whole thing.

Adding Powershell Job Steps To Existing SQL Agent Jobs

Rob Sewell uses Powershell to add a Powershell job step to a set of existing SQL Agent jobs:

I put all of our jobs that I required on the estate into a variable called $Jobs. (You will need to fill the $Servers variable with the names of your instances, maybe from a database or CMS or a text file and of course you can add more logic to filter those servers as required.

$Jobs = (Get-SQLAgentJob -ServerInstance $Servers).Where{$_.Name -like '*PartOfNameOfJob*' -and $_.IsEnabled -eq $true}

Of course to add a PowerShell Job step the target server needs to be SQL 2008 or higher. If you have an estate with older versions it is worth creating a SMO server object (you can use a snippet) and checking the version and then getting the jobs like this

Click through for the process.

Preventing Event Storms

Kenneth Fisher has some good advice when dealing with event notifications:

One of the most common ways to get an event notification is by email. So what happens when you get 500 emails in a day and only one or two are actionable? Do you read every single email? Spending quite literally hours to find those one or two gems? Or do you just ignore the whole lot and wait for some other notification that there is a problem. Say, by a user calling you?

Next, let’s say you have a job that runs every few minutes checking if an instance is down. When that instance goes down you get an immediate email. Which is awesome! Of course then while you are trying to fix the issue you get dozens more emails about the same outage. That is at best distracting and at worst makes it take longer for you to fix the issue.

Fun story time:  at one point during my work career, there was a person (not me!) who accidentally broke every single SQL Agent job on dozens of instances and nobody noticed it for hours.  These weren’t production instances so it wasn’t the end of the world or anything…except that included in the broken jobs were a bunch which ran every minute.  And alerted every minute.  Via e-mail.  The entire database team essentially lost e-mail access for 3 days as there were so many messages coming in that it overwhelmed our provider’s ability to serve messages to us.  This type of mistake can happen, and if we had put into place some of the things Kenneth talks about, the consequences would have been less severe.

Improving Agent Alerts

Chris Bell has a way of making SQL Agent error messages a lot better:

Not very helpful. Sure, I know the job failed, and what step it failed on, but now I have to connect to the agent and look up the history to determine if this is something I have to worry about.

It would be nice to receive the details seen in the history of the job showing up in the email alert received.

Recently I have been working with systems that had all the alert on failure configured so we knew when things failed and could jump on re-running them if needed. We even had them showing up into a data team slack channel, so we had a history as well as notification to everyone on the team at the same time. The problem is that there were not any details in the alerts we received so we had to be able to connect and figure out what to do next or hope that our paid monitoring service would act on something after reading the details of the failure.

Chris has provided a script and gives some recommendations on job configuration which might reduce the number of alerts you get.

Using Powershell To Add SQL Agent Job Steps

Rob Sewell gives a detailed walkthrough of a small Powershell script which adds a job step to every SQL Server Agent job:

This code was run on PowerShell version 5 and will not run on PowerShell version 3 or earlier as it uses the where method
I put all of our jobs that I required on the estate into a variable called $Jobs. (You will need to fill the $Servers variable with the names of your instances, maybe from a database or CMS or a text file

Click through for the script and line-by-line explanation.

Altering Job Steps With Powershell

Rob Sewell uses Powershell to modify hundreds SQL Agent job steps on hundreds of SQL Server instances:

We will use the sqlserver module, so you will need to have installed the latest version of SSMS from https://sqlps.io/dl

This code was run using PowerShell version 5 and will not work on Powershell version 3 or lower as it uses the where method.

Lets grab all of our jobs on the estate. (You will need to fill the $Servers variable with the names of your instances, maybe from a database or CMS or a text file)

One oddity with SQL Agent jobs is that you absolutely need to call the Alter() method at the end or else the changes will not actually take effect.

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April 2017
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