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Category: Administration

When Shrinking Makes Sense

Published 2023-01-10 by Kevin Feasel

Eitan Blumin reminds us that database shrinking isn’t always bad:

Shrinking databases and database files in SQL Server is a widely known “worst practice”.

Usually, it’s because it’s assumed that the database files are expected to auto-grow again after the shrink.
So, in truth, it’s not the shrink itself that’s the problem… It’s the auto-growth!

But… What if you DON’T expect the database file to auto-grow back to what it was before?
For example, what if you truncated/deleted/migrated/archived huge chunks of data from your database, which you don’t expect to be returned later? Or what if you performed a massive data compression or migrated to clustered columnstore indexes, which reduced your data size significantly?

Read on for more thoughts along these lines, problems you might run into, and scripts to help you along the way.

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Creating an Instance Alias in SQL Server 2022

Published 2023-01-10 by Kevin Feasel

Marco Russo asks, what’s in a name?

If you create server aliases for SQL Server connections, you should be aware of the changes introduced in SQL Server 2022. At SQLBI we use aliases to identify the server’s name in the connection of our samples (Power BI files and Analysis Services model), so this short article should help those who face similar requirements.

Read on to learn what that change is and how you can work around it.

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A Review of Prometheus Changes at PromCon

Published 2023-01-03 by Kevin Feasel

B.C. Gain reports on sessions from PromCon EU 2022:

Prometheus’ installations are now in the hundreds of thousands range with millions of users, Richard (RichiH) Hartmann, director of community at Grafana Labs and a CNCF Technical Advisory Group Observability chair, said during his talk “I don’t have to convince this room that Prometheus is a de facto standard in cloud native metric based monitoring.”

But as Prometheus’ maintainers celebrate its 10-year anniversary, the community’s needs for monitoring Kubernetes are evolving quickly. Users are also becoming smarter about what they want and need. PromCon EU 2022, held in Munich in November, the Prometheus annual user’s conference, served as a forum about how and why Prometheus must evolve and what Prometheus maintainers must do.

Prometheus is a critical part of the modern service monitoring stack; read on to learn more about histogram updates and work at the core which should help Prometheus users along the way.

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Alert Setup with Azure Monitor

Published 2022-12-30 by Kevin Feasel

Sunil Verma sounds the alarm:

For this instance, we will setup an alert and action to determine and send out a notification when a Virtual machine has been stopped and also could be restarted whenever such conditions has met.

1. Firstly, Go to search pane on the Azure portal search monitor, click on alert inside monitor and create an alert rule. Further, specify a scope for what you want to setup alert. On this occasion, I am setting it for virtual machine.

Read on to learn more about what Azure Monitor does, as well as the steps to set up an alert and an action.

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Moving Stack Overflow to Azure

Published 2022-12-28 by Kevin Feasel

Aaron Bertrand gets into the whats and wherefores:

Like many companies, Stack Overflow is trying to get out of the business of running our architecture in our own data centers; instead, we want to offload some of the more mundane parts of system administration to a cloud service offering like Azure.

I’m going to cut to the chase for the purpose of this article and concede we’ve already decided on Azure for the majority of our infrastructure and, most importantly to me, our databases.

Click through to learn what their plan is and why Aaron & co went that particular route.

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Troubleshooting Memory Constraints in SQL Server

Published 2022-12-27 by Kevin Feasel

Ajay Dwivedi is running low on memory:

Memory Pressure on SQL Server is very common and is presented as Memory Grant Pending metric in the above dashboard screenshot. In my previous blog Troubleshooting SQL Server With High Memory Grants, I discussed what actions should be taken in order to get the server out of constant memory grant issues in real-time.

For long-term resolution, there are various metrics to be validated before making any decision.

Read on for several tips to help you decide the best course of action.

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From SQL Server to Cassandra

Published 2022-12-22 by Kevin Feasel

Lewis DiFelice shares some lessons learned:

The first 6 months were rough. The cluster had been in operation for more than 6 months but was not doing too well. Performance was poor and, worse, it frequently crashed. It was not a fun time. But eventually, the problems got fixed. 

There were several issues (including my inexperience) that caused these problems, but the core one was that the original developer had treated it like another relational database. 

Read on for a few tips to make learning (and managing) Apache Cassandra a little easier.

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Breaking the World with auto_explain

Published 2022-12-21 by Kevin Feasel

Ryan Lambert gets a lot of explanation:

Postgres has a handy module called auto_explain. The auto_explain module lives up to its name: it runs EXPLAIN automatically for you. The intent for this module is to automatically provide information useful for troubleshooting about your slow queries as they happen. This post outlines a pitfall I recently discovered with auto_explain. Luckily for us, it’s an easy thing to avoid.

I discovered this by running CREATE EXTENSION postgis; and watching it run for quite a while before failing with an out of disk space error. That is not my typical experience with a simple CREATE EXTENSION command!

Read on to learn what happened and how you can prevent making a similar mistake.

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Checking if Cross-Database Ownership Chaining is On

Published 2022-12-16 by Kevin Feasel

Tom Collins performs a check:

Cross-database ownership chaining is a SQL Server  security feature allowing database users  access to other database objects hosted on the same SQL server instance, in the case where database  users don’t have access granted explicitly

Tom shows us whether it is on as well as how to enable it. I’d recommend not enabling it at all and using module signing instead.

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Identifying Rows in sp_wait_for_database_copy)_sync

Published 2022-12-14 by Kevin Feasel

Jose Manuel Jurado Diaz troubleshoots a problem:

As you could see in this public documentation Auto-failover groups overview & best practices – Azure SQL Database | Microsoft Learn about sp_wait_for_database_copy_sync “sp_wait_for_database_copy_sync prevents data loss after geo-failover for specific transactions, but does not guarantee full synchronization for read access. The delay caused by a sp_wait_for_database_copy_sync procedure call can be significant and depends on the size of the not yet transmitted transaction log on the primary at the time of the call.”

Our customer asked about several scenarios to understand this behaviour and also, verify if there is possible to identify the rows that have not been synced. For this, I developed a POC to test it:

Read on to see what you’d need to do.

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