Azure SQL DB Managed Instances: Trace Flags, Ahoy!

When you talk to people from Microsoft

They’re all “aw shucks” about Trace Flags.

• “Don’t really need’em!”
• “Eh, haven’t used one in years.”
• “Sometimes they’re good for troubleshooting, but…”

Then you hop on a managed instance (where you’re not allowed to turn Trace Flags on or off), and you see what they have turned on.

If you head over to Konstantin Taranov’s GitHub repo for Trace Flags, you can decode some of them.

Missing from the list:

• 2591
• 3447 (but 3448 is there, which is supposed to help fix an issue with hung Mirrored databases)
• 3978
• 4141
• 5521
• 7838
• 8037
• 8054
• 8057
• 8063
• 8065
• 9041
• 9537
• 9570
• 9883
• 9905
• 9934
• 9940
• 9941

See where I’m going with this? Konstantin has a GREAT LIST but there are still 19 unknowns enabled on every Managed Instance.

Kinda makes you wonder what all these Trace Flags are up to behind the Redmond Curtain.

If you know what any of them do, feel free to leave a comment — or better yet, add an Issue for Konstantin so he can keep his list up to date.

Some of them are startup Trace Flags, so if you’re aiming to do some poking around, it may not help you to just flip them on.

Thanks for reading!