Locking and Blocking (6) – NoLock

Nolock table hint tells SQL Server engine to not place locks to rows and/or pages while reading them. With this hint enabled, query will not be blocked by any row level modification. It’s equivalent to READUNCOMMITTED table hint in which it allows query return uncommitted data. Many people probably already know that schema stability lock will be applied to the table being access with this table hint, but it’s not always the trueth. In some cases, it will apply Shared lock to the HOBT — partition.

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