Press "Enter" to skip to content

Month: July 2024

Database Snapshots for Deployment and Rollback

Published 2024-07-19 by Kevin Feasel

Andy Brownsword hits upon an underrated feature in SQL Server:

Deploying database changes are relatively easy. Where things get complicated is the rollback. Sure, it’s easy to script out and revert a procedure to a previous version, but what about destructive changes?

In this post we’ll look at how we can use Database Snapshots to remove some of the headache that comes with rolling back changes.

Read on to learn more. The most exciting thing I did with database snapshots was to create a simple app for my developers to take a snapshot (without needing to know the T-SQL behind it), make whatever changes they needed to, and then roll back or roll forward the changes.

Comments closed

Dealing with AG Secondaries Falling Behind

Published 2024-07-18 by Kevin Feasel

David Fowler troubleshoots a wait type:

Are you struggling with a laggy redo and a build up in the redo queue on your readonly secondaries? Are you suffering with high PARALLEL_REDO_TRAN_TURN waits? Then this magic remedy could cure your ailments.

Read on to learn more about the parallel redo process and one thing you can do if it’s falling too far behind. I wouldn’t permanently switch back to serial redo, but maybe make that switch if there’s some consistent pattern to when the process falls behind.

Comments closed

Type 2 SCDs in Microsoft Fabric

Published 2024-07-18 by Kevin Feasel

Reza Rad has changes to make:

In the previous article, I explained SCD (Slowly Changing Dimension) and its different types. In this article, I’ll show you how to implement SCD Type 2 (one of the most common types) using Microsoft Fabric and Power BI. This article includes using Lakehouse, Dataflow, Warehouse, Data Pipeline, SQL Stored Procedures, Power BI Semantic model, and report in Microsoft Fabric.

Click through to learn more about the structure of a type-2 slowly changing dimension, as well as how you can store and load this information to track changes over time.

Comments closed

Viewing the File System of an ADO Pipeline Agent

Published 2024-07-18 by Kevin Feasel

Justin Bird goes spelunking:

There are several predefined variables that you can use within an Azure DevOps pipeline, some of which allow you to reference locations on the pipeline agent file system. Examples of when to use them might be to pick up a file from the downloaded repository or to describe where to output a build. For example the variable $(Build.ArtifactStagingDirectory) will be replaced during the defining of the pipeline job with the respective filepath.

I find it difficult at times to work abstractly with the file system, and so I use this template to visualise the file system for debugging purposes, to observe the outcome of my code, and to make sure I’m picking the right variable.

Click through for some more information about pre-defined variables and a code snippet Justin uses to view filesystem details.

Comments closed

Choosing between Azure SQL DB Ledger and Azure Confidential Ledger

Published 2024-07-18 by Kevin Feasel

Pieter Vanhove reminds me that ledger tables exist:

Ledger technology is a way of storing data that ensures its integrity, immutability, and verifiability. It can be used for scenarios where trust and transparency are essential, such as financial transactions, supply chain tracking, or regulatory compliance. Azure offers two services that leverage ledger technology to provide tamper-proof data storage: ledger in Azure SQL Database and Azure Confidential Ledger. In this blog post, we will compare these two services and help you decide which one is best suited for your needs.

Read on for the comparison. I think the answer for most cases is “neither” but there are specific times when ledger tables could make a good amount of sense.

Comments closed

Fixing an Error in DBCC CloneDatabase

Published 2024-07-18 by Kevin Feasel

Steve Jones runs into an issue:

This was an interesting error, and I was able to duplicate it, so I decided to write a post on how to find the problem and fix it. The error after running DBCC CLONEDATABASE is:

NO_STATISTICS and NO_QUERYSTORE options turned ON as part of VERIFY_CLONE.
Database cloning for 'atest' has started with target as 'aSmallTest'.
Msg 2601, Level 14, State 1, Line 11
Cannot insert duplicate key row in object 'sys.sysschobjs' with unique index 'clst'. The duplicate key value is (885578193).

The final key value (885578193) for you might be different, but the error is the same.

Read on to learn more about the issue, as well as how Steve was able to fix the problem.

Comments closed

Extracting the End of a String in R

Published 2024-07-17 by Kevin Feasel

Steven Sanderson just wants the conclusion:

Hey useR’s! Today, we’re going to discuss a neat trick: extracting substrings starting from the end of a string. We’ll cover how to achieve this using base R, stringr, and stringi. By the end of this post, you’ll have several tools in your R toolbox for string manipulation. Let’s get started!

Read on to see how you can do it in three separate libraries.

Comments closed

Finding Query History in Snowflake

Published 2024-07-17 by Kevin Feasel

Kevin Wilkie digs into the history:

If you’re running an audit process in SQL Server, you can do this fairly easily. But how many of us work in a place that requires this or has enough space to do this? Sadly, very few of us…

If you have Query Store running (and why wouldn’t you?) you can find a specific query you were running. But you have to have a specific something you can search for…

But can you get just a list of what you specifically ran in order? Not that I can find….

My recollection is that, if you’re using Azure SQL Database, that auditing is on by default (or you can turn it on with a toggle switch or radio buttion). For Azure Synapse Analytics dedicated SQL pools, there are a few DMVs that cover query operations. But yeah, in general, it’s something you’d need to enable first.

Comments closed