Brent Ozar • 9/15/2026

“But NOLOCK won’t hurt me if I’m using an index!”

Brent Ozar demonstrates that using NOLOCK with an index seek can still produce incorrect results. He creates a table with an index, runs an update transaction, and shows that a NOLOCK query with an index hint returns rows that should not exist. This proves that NOLOCK is unsafe even when using index seeks, due to the way SQL Server executes the query plan.

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#indexing #SQL Server #Transactions