DBA Database on Andy M Mallon - AM²

Consuming SQL Agent dates & durations

Fri, 07 Mar 2025 16:17:43 -0500

SQL Agent’s schema is older than me. It handles dates, times, and durations like it’s 1980 by using integers instead of date/time data types. My buddy Aaron Bertrand talks more about Dating Responsibly so that you can have a good datetime with your own database.

I was writing a query to pull recent job failures from SQL Agent’s msdb job history, and knew that I didn’t want to deal with the wonky date/time formats. Specifically, I was querying msdb.dbo.sysjobhistory to find the Start Time, End Time, and Duration of job runs that failed. If you aren’t familiar with that table, you can look at it over in the docs.

Not all stats should be auto-updated

Thu, 29 Aug 2024 11:19:07 -0400

Statistics auto-updates are generally a good thing–auto-update of statistics is the default behavior in SQL Server. Having the freshest information about the data “shape” helps to inform the best selection of an execution plan for queries.

Except for when it doesn’t.

Because It Depends™️

Let’s talk about the trade-offs.

AG secondary is out of sync for hours after index maintenance

Tue, 21 Feb 2023 13:17:04 -0500

Question

We have a 3TB OLTP database running Siemens Opcenter MES software at one of our manufacturing plants in China. This is setup in an Always-On Availability group with one secondary node. As this is a manufacturing plant, we are only provided 11 1/2 hours every two weeks to run index maintenance when the plant is not running production. We use Hallengren scripts to run this index maintenance.

Querying SERVERPROPERTY() and DATABASEPROPERTYEX() from a view (without knowing magic)

Fri, 17 Dec 2021 11:11:50 -0500

I’m not going to beat around the bush. I hate the SERVERPROPERTY() and DATABASEPROPERTYEX() system functions.

Loathing

The thing I hate the most about these two functions is that you need to know the right magic spells to make them work. Let’s look at SERVERPROPERTY() first. The syntax for the function is SERVERPROPERTY( ‘propertyname’ ), which is easy enough syntax, but the list of values for propertyname isn’t discoverable from SQL Server metadata, DMVs, or even IntelliSense. Instead, I need to check the docs for the list of allowable values. These property names are essentially magic words, and I need to check my spell book to make sure I get it right.

log_reuse_wait_desc = AVAILABILITY_REPLICA, log is 100% full but AG is all fine

Sun, 28 Nov 2021 18:58:02 -0500

Question

That's a weird scenario. The transaction log is full. It waits on AG. AG is all good. No latency, last commit/hardened time is almost real-time on all the nodes. The Estimated Recovery Time is zero. I checked this from the primary node and secondaries as well (in case if Dashboard is not updating). This page lists only two reasons for this error, a delivery latency and redo latency. Nothing applies to my system. How to troubleshoot this further?

T-SQL Tuesday #143: My favorite short scripts

Tue, 12 Oct 2021 10:00:22 -0400

For this month's T-SQL Tuesday, John McCormack (blog) asks us: “What are your go-to short, handy scripts”? I've got so many handy dandy scripts, it was hard to choose.

Where to start?

I have so many go-to scripts that are short, amazing, and I use all the time. I’ve been using SQL Server since the turn of the century, and over the last two decades, I’ve found and written a lot of helpful things. And I have a terrible memory, so even if it’s just a few lines, I often keep it bookmarked or saved for when I need it. As an aside–remember that having a folder of utility scripts isn’t a sign of weakness or incompetence. If anything, it’s the opposite–those utility scripts are basically all battle scars for the database battles you’ve fought over your career. As we become senior, we just fine-tune our collection. With seniority, you don’t stop having that collection of scripts–you just get better at curating them, at making them generic & reusable.

What time is it in Oz?

Tue, 05 Oct 2021 15:54:03 -0400

There was a recent post on Database Administrators, where there was some confusion over Daylight Saving Time(DST) in Australian timezones. Let’s be honest though–timezones are confusing, especially when DST comes into play. Arizona Time doesn’t observe Daylight Saving Time, so sometimes it’s the same as Mountain Time, and sometimes it’s Pacific Time.

Stop using sp_hexadecimal & sp_help_revlogin

Tue, 06 Jul 2021 09:00:52 -0400

Since I started at Stack Overflow (read archived tweet) , I’ve had the chance to see some of the interesting challenges with running our databases at our scale.

My coworker Taryn Pratt (blog) recently blogged about fighting with deadlocks related to Stack Overflow for Teams.

Lots of logins

Taryn mentions in her post that each team gets their own login, user, schema, etc. This means we have a lot of logins. Additionally, we use Availability Groups for our High Availability, which means we need to keep those logins in sync across AG Replicas.

Blocking with OBJECT_NAME()

Tue, 24 Dec 2019 10:38:36 -0500

As a DBA, you probably use the OBJECT_NAME() function quite a bit. I know I do. If you aren’t familiar with it, you can read the documentation if you want, but it’s a pretty straightforward function that converts object IDs into object names.

I ran into a scenario where one of my scripts in my stored procedures in my DBA Database was being blocked, and it turned out that using OBJECT_NAME() was the culprit.

Code to purge data based on creation date

Thu, 04 Apr 2019 08:30:16 -0400

Yesterday, I talked about batching deletes, and the day before I talked about how much I like to delete data, and why it’s necessary to do it, despite being a data packrat.

Today, let’s look at just one scenario, and how I like to handle it. In my experience, this is one of the most common purge requirements (and probably the easiest), so first, let’s look at the business requirements.

TSQL Tuesday #104: dbo.Check_FileSize

Mon, 09 Jul 2018 23:18:12 -0400

It’s T-SQL Tuesday, the blog party that SQL Server expert Adam Machanic (blog) started. This month’s episode is hosted by Bert Wagner (blog | vlog). The topic: Code You Would Hate To Live Without

It’s been a little bit since the last T-SQL Tuesday I joined, when I blogged about religion & politics (aka, Tabs vs Spaces). When I saw Bert’s excellent topic this month, I decided I’d try to get back on the horse again and do join the blog party again this month.

Parsing file names from paths using T-SQL

Wed, 17 Jan 2018 07:00:40 -0500

SQL Server is great at a lot of things. I spend a lot of time blogging about all the cool things that SQL Server does. But (you knew there was a “but”, didn’t you) SQL Server isn’t great at everything. Lets write about something that SQL Server is bad at.

Finding active transactions

Tue, 02 Jan 2018 09:04:07 -0500

Have you ever forgot to commit a transaction? Maybe you’ve even left for lunch and caused a problem while you were gone. Uncommitted transactions can cause all sorts of problems–not just blocking, but it can affect your Availability Groups & Mirroring, your TempDB version store if you’re using one of the snapshot isolation levels.

Alerting on SQL Server Blocking

Mon, 18 Dec 2017 09:00:02 -0500

Identifying blocking is one of the most basic things that a DBA should be monitoring for. I previously wrote about how to identify blocking in SQL Server and find the leading blocker. Recently, my friend Jim Donahoe (blog) asked me about setting up email alerts related to blocking, which prompted me to clean up some additional code I have that does just this. If you haven’t already read my previous post, you should probably do that now.

Finding the Leader Blocker

Thu, 26 Oct 2017 23:55:09 -0400

During the course of normal processing in a database, blocking happens. Blocking is “by design” because your database is on ACID. In an OLTP database, most of your transactions are short in duration, so we expect blocking to also be short in duration. If blocking occurs for a long time, this can cause problems.

xp_sqlagent_enum_jobs alternative

Thu, 18 Feb 2016 10:00:21 -0500

What's `xp_sqlagent_enum_jobs`?

If you landed on this post, I'm guessing you know the answer to this, so I'll be quick. `xp_sqlagent_enum_jobs` is an undocumented (and thus, unsupported) extended procedure that gives information on whether a job is currently running, when it last ran, when it runs next, etc.

The supported alternative is to use sp_help_job (which calls xp_sqlagent_enum_jobs), but sp_help_job is difficult to use in automation because trying to do INSERT #temp EXEC sp_help_job; will result in an error due to nested INSERT...EXEC statements (Error 8164: “An INSERT EXEC statement cannot be nested.”). As a result, people often turn to calling the unsupported xp directly.

Planning for an outage: Phone numbers

Tue, 15 Sep 2015 13:29:00 -0400

Who ya gonna call?

If there's somethin' strange in your neighborhood Who ya gonna call? If it's something weird and it won't look good Who ya gonna call?

This summer, they've been taping the new Ghostbusters movie in Boston. It's pretty cool to see the Ghostbusters car rolling through the city.

Unfortunately, the Ghostbusters aren’t the right person to call when something goes boom in your data center. I’m not saying I haven’t used ghosts and gremlins as part of a root cause analysis before–but even Dan Aykroyd and Bill Murray can’t help you when there’s a storage or network issue. I’m skeptical that Kristen Wiig will be much better.

Formatting HTML emails in SQL

Wed, 26 Nov 2014 15:34:00 -0500

When I am writing monitoring/alerting stored procedures for my SQL Servers, its important to have those alerts be well-formatted. I like to minimize the amount of time I spend sorting through emails & alerts, and part of that is making sure that I can determine the urgency & priority of an email alert at a mere glance. More importantly, it has to be equally useful to me at my desk & on my mobile.

DBA Database on Andy M Mallon - AM²

Consuming SQL Agent dates & durations

Not all stats should be auto-updated

Except for when it doesn’t.

Because It Depends™️

AG secondary is out of sync for hours after index maintenance

Question

Querying SERVERPROPERTY() and DATABASEPROPERTYEX() from a view (without knowing magic)

Loathing

log_reuse_wait_desc = AVAILABILITY_REPLICA, log is 100% full but AG is all fine

Question

T-SQL Tuesday #143: My favorite short scripts

Where to start?

What time is it in Oz?

Stop using sp_hexadecimal & sp_help_revlogin

Lots of logins

Blocking with OBJECT_NAME()

Code to purge data based on creation date

TSQL Tuesday #104: dbo.Check_FileSize

Parsing file names from paths using T-SQL

Finding active transactions

Alerting on SQL Server Blocking

Finding the Leader Blocker

xp_sqlagent_enum_jobs alternative

What's xp_sqlagent_enum_jobs?

Planning for an outage: Phone numbers

Who ya gonna call?

Formatting HTML emails in SQL

What's `xp_sqlagent_enum_jobs`?