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Day: March 9, 2026

Data Type Precedence in SQL Server

Published 2026-03-09 by Kevin Feasel

Louis Davidson has a type:

There is one topic in query and equation writing that is constantly a minor issue for SQL programmers: implicit data type conversions. Whenever you don’t specifically state the datatype of an expression, like when you write SELECT 1;, it can feel a bit of a mystery what the datatypes of your literal values are. Like in this case, what is 1 ? You probably know from experience that this is an integer, but then what happens when you compare CAST(1 as bit) to the literal 1. Is that literal 1 now a bit? Or is it still an integer?

Perhaps even more importantly, why does this query succeed?

Click through to learn more.

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Porting Statistics in PostgreSQL

Published 2026-03-09 by Kevin Feasel

Radim Marek imports production statistics:

In the previous article we covered how the PostgreSQL planner reads pg_class and pg_statistic to estimate row counts, choose join strategies, and decide whether an index scan is worth it. The message was clear: when statistics are wrong, everything else goes with it.

But there was one thing we didn’t talk about. Statistics are specific to the database cluster that generated them. The primary way to populate them is `ANALYZE` which requires the actual data.

Click through to see how Postgres handles this. It’s quite similar to SQL Server’s DBCC CLONEDATABASE in practice, it seems.

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Avoid Hard-Coding Linked Server Names

Published 2026-03-09 by Kevin Feasel

Greg Low provides some good advice:

I’m not a great fan of linked servers in SQL Server but they are often necessary. If I’m working with the latest version of SQL Server, I really prefer to use External Data Sources and External Tables. But not everyone is on the latest version. In the meantime, what I see all the time, is people hardcoding server names like this:

SDUPROD2022.WWIDB.Payroll.Employees

That makes your code really hard to manage.

Read on for several options. At a prior company quite a while ago, we went with DNS entries and they worked reasonably well.

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Preview-Only Steps in Microsoft Fabric Dataflows

Published 2026-03-09 by Kevin Feasel

Chris Webb covers a new feature:

I have been spending a lot of time recently investigating the new performance-related features that have rolled out in Fabric Dataflows over the last few months, so expect a lot of blog posts on this subject in the near future. Probably my favourite of these features is Preview-Only steps: they make such a big difference to my quality of life as a Dataflows developer.

The basic idea (which you can read about in the very detailed docs here) is that you can add steps to a query inside a Dataflow that are only executed when you are editing the query and looking at data in the preview pane; when the Dataflow is refreshed these steps are ignored. This means you can do things like add filters, remove columns or summarise data while you’re editing the Dataflow in order to make the performance of the editor faster or debug data problems. It’s all very straightforward and works well.

First up, that feature is pretty interesting, though I could see things break if you only do your testing in the preview pane. Second, what Chris does with this is quite interesting.

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Troubleshooting Bad Request in ADF Pipelines

Published 2026-03-09 by Kevin Feasel

Koen Verbeeck said something bad:

A while ago I blogged about a use case where a pipeline fails during debugging with a BadRequest error, even though it validates successfully. If you’re wondering, this is the helpful error message that you get:

Click through for an image of the 400 Bad Request message, how Koen fixed it originally, and then a different scenario in which that 400 message popped up.

Ultimately, a 400 Bad Request comes down to “You sent me information that doesn’t make sense and I can’t fulfill your request, so fix it, dummy.” 400 status codes are very rude and insulting. Especially 418–that thing has a mouth like a sailor’s.

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