A Fine Slice Of SQL Server
Reitse Eskens hit an interesting issue:
The issue is quite simple. A text needs to be converted into a SHA2_256 hash for some authentication reasons. The example shown here is simplified. The thing is, the outcome of the hash isn’t accepted by the authorising party and when the input is checked via an online MD5 hashing site, there’s a difference between that output and that from the SQL Script.
Read on to see what the problem is and how it can affect you.
Comments closedSteve Jones gives it the ol’ college try:
This is a common error handling technique in other languages. C# uses it, as does Java, while Python has TRY EXCEPT. There are other examples, but these are good habits to get into when you don’t know how code will behave or if there is something in your data or environment that could cause an issue.
In SQL, I think many of us get used to writing one statement in a query and forget to do error handling, or transactions. However, this can be a good habit as your code might grow and people might add more statements that should execute.
Read on for a few examples of how to use SQL Server’s TRY-CATCH functionality. It’s not perfect, but as Steve shows, there are definitely good uses for it.
Comments closedReitse Eskens pushes the envelope:
In my previous blog on Fabric and loadtesting, I ended with not really knowing how PowerBI would respond to all these rows. After creating and presenting a session on this subject, it’s time to dig into this part of Fabric as well. There were questions and I made promises. So here goes! This blog will only show the F2 experience as that’s where things went off the road. And, as I’ve shown in the previous blog, the CU count doesn’t change between SKU’s, only the amount of SKU’s available changes.
This blog isn’t meant to scold Fabric or make it look silly, I’m the one who’s silly. The goal is to show some limitations, a way you can do some load testing and help you find your way in the available metrics.
Read on to see what Reitse has gotten into.
Comments closedDeborah Melkin shares a lesson:
I’ve been working on a project where I have to do a lot of interesting data manipulation. Unfortunately, dealing with implicit conversions has been part of the norm. So naturally, I managed to run across an interesting scenario that had me stumped, thinking that I ran into a strange edge case.
The tl;dr version is that this wasn’t an edge case or some undocumented issue or a bug or anything other than the db engine doing its job. I was looking at one scenario and missed the rest of the clues. But it’s worth sharing how these things are easily missed.
Click through for the full story.
Comments closedReitse Eskens hits a weird error:
One of the transformations is to change one primary key column from integer to GUID. This is something you can do with some trickery you’ll see in the code. But what I found was that, even though the primary key is unique, the GUID’s weren’t. And then the fun starts digging into the why…
Read on for the research Reitse performed. I don’t even have a good guess for this, it’s so weird. It feels like a bug but it’s weird regardless.
Comments closedKendra Little explains a problem:
If you use readable secondaries in Availability Groups or Read-Scale out instances in Azure SQL Managed Instance, you may have queries fail repeatedly if there is a glitch and statistics are not successfully “refreshed” on the secondary replica. Those queries may keep failing until you manually intervene.
This has been the case for a few years, and it’s unclear if Microsoft will fix this. There is a well established support deflection article which documents the issue and provides ‘workarounds’.
Read on for Kendra’s thoughts. I haven’t run into this before, myself, but I also don’t tend to make very heavy use of readable secondaries.
Comments closedShane 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.
Comments closedEitan 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.
Comments closedSteve Jones shows ERROR_MESSAGE()’s extended family:
I was working with a customer that was doing some error handling in procs and helped them do some error tracking. As we were working through things, I realized that some of functions working with errors operated differently than I expected.
Read on to learn more about these error functions and the proper way to use them.
Comments closedChen Hirsh doesn’t let failure get in the way of doing work:
Today I stumbled upon a weird behavior in Azure Data Factory (ADF) error handling.
ADF lets us add error handling in the flow control, In this example, I’m trying to copy some data, and if that fails go to on failure branch (red line). If the activity succeeded, go to on success branch (green line)
These work great (If you can call a failure great…).
Let’s take another step. What if I want to run another activity at the end, no matter if the copy succeeded or failed?
The behavior is a bit weird, as it doesn’t work quite the way you’d expect. Chen, however, shows us how to do it.
Comments closed