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Category: Administration

Feature Toggles for Databases

Published 2024-02-20 by Kevin Feasel

Phil Factor discusses feature toggles for the database:

In software development the concept of feature toggles are used to selectively turn on and off features. They are, for example, used to restrict some newly introduced features to a select group to see how these features work. While this concept has been long used for user-facing application code, it is also a practice that is useful for database code.

In databases, feature toggles are used for several loosely related purposes. One common use is to separate, or decouple, rollout of database features from deployment of new versions of the application code. This allows developers to release software faster and with less risk.

The idea of using roles to determine whether a given user should see a particular feature makes sense, though I was a bit confused at first because I was thinking about feature flags: behavioral changes you slowly turn on for groups of people. This is a bit different.

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Enabling SQL Agent after Upgrading from Express Edition

Published 2024-02-19 by Kevin Feasel

Warwick Rudd ponies up the cash:

With the above limitations, this product can provide all of the functionality for your application to operate as required. Because there is no SQL Agent service in this edition this makes it more difficult for you to implement scheduled database maintenance. We are not going to discuss ways to implement database maintenance on an Express edition of SQL Server in this post.

But at some point in time you may find yourself in the position that you need to perform an upgrade of editions. This may or may not include and upgrade of versions. An upgrade to the version can be achieved and can bring benefits of its own. Normally, I would not be writing about and recommending performing in-place upgrades. However, sometimes due to restrictions of vendor applications it is a requirement to perform an in-place upgrade. 

Read on to see what you’d need to do, knowing that Express Edition does not come with a SQL Server Agent and does not perform the appropriate setup for one.

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Checking SQL Server Connectivity with Powershell in Parallel

Published 2024-02-16 by Kevin Feasel

Rod Edwards builds a script:

The chances are that you have other systems monitoring your SQL servers already, so this task isn’t required at all. However, sometimes a quick ‘knock on the door of SQL’ to confirm a response isn’t a bad thing as a sanity check.

So, building on that, we’re going to use the same technique to essentially perform a sweep of our estate (with a few bells and whistles added) to give us a colour coded quick view of service status like below, with a little bit of additional info.

Click through for the script and explanation.

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Troubleshooting a Problem with sp_send_dbmail

Published 2024-02-16 by Kevin Feasel

Shane O’Neill applies the Sgt. Schultz defense:

I don’t like posting about issues unless I fundamentally understand the root cause. That’s not the case here. A lot of the explanation here will be hand-waving while spouting “here be dragons, and giants, and three-headed dogs”, but I know enough to give you the gist of the issue.

Click through for a fun story about Kerberos and behavioral changes after absolutely nothing happened.

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Horizontal Scale in Postgres with PL/Proxy

Published 2024-02-14 by Kevin Feasel

Umair Shahid gives us the rundown on one mechanism to scale out Postgres:

As databases scale and user demands intensify, the challenge of maintaining performance increases. While PostgreSQL was originally designed (40 years ago!) to scale up, but increasing demands on the database have created the need to enable it to scale horizontally. PL/Proxy is a database partitioning system designed to simplify the process of distributing database loads across multiple servers. It acts as a transparent layer between the application and the database, enabling queries to be directed to the appropriate shard or partition based on predefined rules.

This article will dive into PL/Proxy, taking a look at its benefits, use cases, and best practices to enhance PostgreSQL’s performance through effective scaling.

Click through to learn more about this product.

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Troubleshooting Performance around a Data Purge Process

Published 2024-02-14 by Kevin Feasel

Andy Mallon troubleshoots an issue:

In January, one of our Staff Engineers sent the following message to the DBRE help channel in Slack:

Morning folks, we had a pretty significant wait spike on the [database]. Circuit breakers closed and reopened quickly. Is anyone immediately aware of a reason why this could’ve happened?

Read on for Andy’s quick analysis and then the root cause and solution.

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Forced Quorum Failures with WSFC

Published 2024-02-13 by Kevin Feasel

Eitan Blumin can’t reach quorum:

The incident started with a late-night phone call from one of our customers (it’s always a late-night phone call, isn’t it?).

They reported that during a DR exercise on their production environment (Chaos Engineering, anyone?) their entire cluster failed and they weren’t able to bring any of the replicas back online.

Click through for the full story, including what happened, why it happened, and what you can do to prevent similar problems in the future.

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Automating Microsoft Fabric Capacity Scaling via Logic App

Published 2024-02-12 by Kevin Feasel

Soheil Bakhshi does some scaling:

In a previous post I explained how to manage the capacity costs of a Fabric F capacity (under Pay-As-You-Go pricing model) using Logic Apps to Suspend and Resume it.

A customer who read my previous blog asked me “Can we use a similar method to scale up and down before and after specific workloads?”. This blog post is to answer exactly that.

This is pretty neat, though I wonder how long it takes and how much downtime it produces.

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Monitoring if an Azure Server Goes Offline

Published 2024-02-06 by Kevin Feasel

Paul Bergson builds an alert:

My miniature schnauzer, Raven, is a smart and lively dog who loves to hunt for rodents in the yard. She has a keen sense of smell and can detect the slightest movement of her prey. She barks loudly to alert me whenever she finds a potential target and chases after it with all her speed. However, the rodents are too cunning and often escape to a tree or a hole in the ground before she can catch them. She then returns to me with a disappointed look on her face, hoping for a treat or a pat on the head.

Azure Monitor is like Raven, but much more efficient and reliable. It can monitor your Azure servers and detect when they go offline in ~1 minute. It can also alert you via email, SMS, or webhook when something goes wrong, so you can take action to fix it. With Azure Monitor, you can stay on top of your server’s health and performance.

Read on to see how you can use Azure Monitor and build policies, with much less cleanup requirement than a dog.

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Purging Lots of Backup History

Published 2024-02-05 by Kevin Feasel

David Wiseman needs to clear out a significant amount of backup history:

Recently, I encountered an issue running sp_delete_backuphistory on servers that hosted a large number of databases with frequent log backup & restore operations. The clean up task hadn’t been scheduled and the history tables had grown very large over several months. The msdb databases was also hosted on a volume with limited IOPs.

Attempting to run sp_delete_backuphistory under these conditions you will likely encounter these issues:

Click through for that list of issues, as well as a way of mitigating the problem. I’ve noticed this kind of pattern appears fairly often in Microsoft-provided cleanup procedures: the code works well until you reach a certain scale, at which point it falls over. It’d be great if the original sp_delete_backuphistory performed batch deletion from the get-go, but David shows us a way to get around the issue.

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