Error Handling – Curated SQL

REGEXP_LIKE() and Its Return Value

Published 2026-09-01 by Kevin Feasel

I’ve declared a variable and assigned it a value. Now, I want to check if my variable matches the regular pattern of Dutch postal codes. These codes are four numbers followed by two letters. Using a regular expression helps check validity.

My expectation was that this query would return either 1 or TRUE. In any case, a result telling me that the postal code is valid. Instead, it throws an ‘Incorrect syntax error near the keyword ‘REGEXP_LIKE’.

Click through for the screenshot and the explanation.

Identity Column Reseeding and Clashes

Published 2026-09-01 by Kevin Feasel

Dualcore DBA violates Betteridge’s Law of Headlines:

I recently had cause to reseed an identity column on a table in SQL Server, which got me wondering “If we reseed an identity column to a value lower than the existing identity values in the column, could it cause a clash?” Because why wouldn’t you wonder if you can cause something to break, whilst performing a fairly simple task!?

Let’s find out what happens…

Click through for the demonstration.

INFORMATION_SCHEMA and the Fabric Warehouse

Published 2026-08-27 by Kevin Feasel

Louis Davidson bangs his head against a wall:

When we decided to use T-SQL and a Fabric Data Warehouse for our ETL, I started thinking about generating the code with the metadata in the system catalog views or the INFORMATION_SCHEMA. Having done this sort of thing before in SQL Server over the years, it seemed really straightforward. And it kind of is, until it isn’t.

In this blog I want to show you a few ways you need to understand how working with metadata and temp tables varies (sometimes wildly) from the comfortable SQL Server environment and language you know very well, and give tips on how to get around these differences.

Click through for some of the fun you can have with a distributed SQL Server-like product.

MSDB 110_upgrade.sql Failed with Error 574

Published 2026-07-22 by Kevin Feasel

Jordan Boich troubleshoots an issue:

SQL Server won’t start and at first, I couldn’t figure out why. When I logged off for the day on Friday, everything was happy, but when I logged on Monday morning, a heavily used test instance of SQL was not running and wouldn’t start.

Quick side note, and it’s funny looking back on now, but in the moment it sucks. You ever have to start the SQL Server Service from Configuration Manager, and when you right click -> Start, or right click -> Restart you see that green progress bar start to go and under normal healthy circumstances, it probably gets a third of the way through before SQL kicks over. But when you start to see that progress bar start to make more and more progress, you know before it even fails on you that something isn’t going to work right. You start to get that sinking feeling in your stomach. That was me.

Click through for the troubleshooting process as well as the end result.

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Power BI: Database Was Evicted to Balance the CPU Load

Published 2026-07-06 by Kevin Feasel

Chris Webb diagnoses a case of passive voice:

A few months ago I wrote about a rare error – the “Maximum allowable memory allocation” error – that may occur when the physical machine, or node, that a semantic model is running on in the Power BI Service comes under memory pressure. Recently, someone I was working with who was doing some load testing showed me a related error:

The operation was canceled and the database was evicted to balance the CPU load on the node. Please try again later.

Read on to see what causes this.

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Error 1408 with Availability Group Automatic Seeding

Published 2026-07-02 by Kevin Feasel

Sean Gallardy troubleshoots an error:

This used to be a very hot topic around SQL Server 2016 when automatic seeding first came out, then everyone learned how automatic seeding was just manual seeding but done for you and the topic went away. A decade later, it’s somehow back to being a hot topic. I guess all that is old is new again.

Error 1408 states that the database doesn’t have enough log to find a starting point with the primary/principal – which, let’s just use AG terminology from this point on because mirroring has been dead for 14 years and counting.

Mirroring has been dead and yet it lives on in undead form. Regardless of that, Sean provides some good information around what automatic seeding actually means and what you can do if you get stuck with Error 1408.

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Too Many Tables and PostgreSQL

Published 2026-07-02 by Kevin Feasel

Laurenz Albe uncovers an oddity:

Recently, I helped a customer investigate database problems. It turned out that these problems could be traced back to too many tables in the database. Since this may come as a surprise to many users, I thought it worth the while to write about it.

Click through to see what was happening, as well as a demonstration of the problem. Granted, when you start talking about tens of thousands of tables, something has gone catastrophically wrong in your database architecture.

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Master Database Compatibility Level

Published 2026-06-30 by Kevin Feasel

Jeff Iannucci explains an issue:

We were attempting to install a troubleshooting stored procedure in the master database of a SQL Server 2016 instance when we received the following error.

Msg 195, Level 15, State 10, Procedure sp_ShootTheTrouble, Line 227 [Batch Start Line 7]

‘TRY_CONVERT’ is not a recognized built-in function name.

This was unexpected, as TRY_CONVERT has been a command since SQL Server 2012. As a consequence, we were unable to install the stored procedure.

Tracking system database compatibility levels is a minor chore but an important one after an upgrade.

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PBIR Files and Second-Class Report Server Citizens

Published 2026-06-19 by Kevin Feasel

Ronald Kraijesteijn tells a tale of woe with Power BI Report Server:

The setup is an on-prem Power BI Report Server, fully patched, running the May 2026 release (1.26.9637.31070, build15.0.1121.109). I had a report I needed to publish, but first I had to swap a whole batch of connection strings. Doing that by hand in Desktop is miserable, so I took a shortcut that turned out to be the root of all my pain. More on that below.

The error was a generic mess and the cause was getting too high for your station and actually expecting something from Power BI Report Server.

I say this as a fellow long-time Power BI Report Server sufferer.

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Postgres NULLs and NOT IN

Published 2026-06-16 by Kevin Feasel

Radim Marek lays out a common issue people experience in PostgreSQL:

A NOT IN query can return the wrong answer without telling you. It is valid SQL, it runs without an error, and it hands back a perfectly well-formed result set that happens to be empty when it should not be. No warning, no hint, nothing in the logs: just zero rows where you expected hundreds, and a database that considers it correct.

Almost always the cause is a single NULL sitting somewhere you forgot to look, combined with two keywords you have typed a thousand times: NOT IN. None of it is a Postgres bug. This is exactly what the SQL standard mandates, implemented faithfully. That is precisely what makes it so easy to walk into, and why the planner could not safely optimize around it for the better part of Postgres’s history. It comes down to one if statement in the parser.

This is a Postgres-specific problem, as the same code runs successfully in SQL Server. But if you are working with Postgres, it’s good to keep track of this behavior, and Radim has solid advice for a proper workaround.

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Category: Error Handling