LATCH_UP

Description

Latches are used to guarantee consistency of non-buffer pool memory structures. The latch processed will be in update mode. Update mode is not just for UPDATE operations. It is used when SQL needs to read then modify a latch, before modification it will place an update on the data then when ready upgrade this to an exclusive latch. Note that high values in this wait do not always mean a problem (e.g. in the case of parallelism)

Resolved by

DBAs and Developers

Suggested solutions

  1. If this wait is experienced further details will need to be retrieved from sys.dm_os_latch_stats
  2. If parallelism is a common latch wait consider optimizing heavy parallel queries via indexing

Additional research

Most common latch classes and what they mean
Diagnosing and Resolving Latch Contention on SQL Server

See more

Consider using ApexSQL Monitor, a Windows and SQL Server monitoring tool able to track SQL Server wait types, including the individual query wait statistics

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