Fun With Undocumented Trace Flags

Joe Obbish has a list of 45 undocumented trace flags:

Below is a list of trace flags which, as far as I can tell, have never been publicly documented. I did not fully investigate many of them and many of the descriptions are just guesses. I make no guarantees and none of these should be used in production. All tests were performed on SQL Server 2017 CU2 with trace flags enabled at the global level.

This is combining a bit of database archaeology and database anthropology.

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Finding Trace Flag Usage With dbachecks

Rob Sewell points out an addition to dbachecks: This will show you the UniqueTag which will enable you to run only that check if you wish AllTags which shows which tags will include that check Config will show you which configuration items can be set for this check The trace flag checks require the app.sqlinstance […]

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Collecting Plan Metrics With Trace Flag 7412

Grant Fritchey shows a lightweight way of capturing plan metrics: I place a lot of emphasis on capturing actual execution plans because of the runtime metrics, but with Trace Flag 7412, we don’t need the plan. This is great news, because capturing execution plans, even using extended events, is an expensive proposition. However, using either […]

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