NOLOCK with DMVs is not a blanket reassurance against monitoring waits. A customer asked about omitting the hint.
SELECT wait_type,waiting_tasks_count,wait_time_ms FROM sys.dm_os_wait_stats ORDER BY wait_time_ms DESC;DMVs expose changing internal state with their own synchronization and collection behavior. NOLOCK does not guarantee consistency or zero locks and waits. Joins to ordinary tables and catalogs bring additional semantics.
My tests found little practical difference. They did not establish a rule for every DMV, function and join. Read the specific documentation and limit expensive text or plan retrieval.
Measure collection overhead and interpret counters over a defined interval. This normal wait inventory does not clear counters. It does not prove every diagnostic query is free. Use release-appropriate permissions.
Reference: Dynamic management objects and version-specific permissions.
Related reading
A DMV hint is not a zero-wait guarantee, it is syntax to evaluate under the specific objects and query.
Published by Pinal Dave on SQLAuthority. More of my work at pinaldave.com.
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