DST changes affecting SQL Server?

Question

DST rules may be changing soon in the US. A bill recently passed the senate unanimously (no its not April fools day), to eliminate standard time and make daylight savings time permanent. If that becomes law, will every on-prem SQL Server instance need to be patched? Or will the monthly Windows patches take care of that?

I'm not clear where timezone and DST logic is handled. Does SQL make calls to Windows to do that? Is it built into SQL? Or is it both?

One concern I have is I'm responsible for 150 on-prem SQL Servers and some of them are WAY out of date. We've got a few servers that go back as far as SQL 2000 and 2005 running on Windows server 2003 and 2008 and I'm not sure patches will even be available should this actually happen.

Answer 1

You can rely on Windows in this case.

As a test you could try one of your SQL 2000 instances right now. Wikiepdia tells me that the current DST scheme in the US went in force in 2007, after the release of SP4. When SQL 2000 was released, March 16th was in Standard Time, now it is Daylight Savings.

Over here, the European Parliament adopted a bill to abolish the change between standard and DST several years ago, and it was up to each country to decide which time zone to be in. However, pandemic and other things has come in between, so nothing has changed. Which I'm personally grateful for.

Answer 2

Hi ChuckHamilton-7817,
SQL Server Engine, Analysis Services, etc. uses/relies on Windows for many date/time functionalities.

And to make sure that Windows has the latest and most accurate time data, Microsoft continuously monitors DST and TZ changes that are announced by governments around the world. Microsoft makes an effort to incorporate these changes to Windows, and publishes an update through Windows Update (WU). Each DST and TZ update that is released through WU will have the latest time data and will also supersede any previously issued DST and TZ update. Please refer to this blog and this doc which might be helpful.

In addition, Windows server 2003 has ended extended support and will not be receiving an update unfortunately.

Best Regards,
Amelia

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