LATCH_NL is the wait type for a Null (NL) mode latch on a non-page internal structure. NL is the no-op of latch modes, and this wait exists purely so the full set of modes (NL, KP, SH, UP, EX, DT) has matching LATCH_* wait types. In practice it is essentially never used.
This page exists so the name has an answer when someone looks it up.
Is It a Problem?
No, and you should essentially never see it with a non-zero value. If a monitoring tool ever shows it accumulating, suspect the tool’s arithmetic before the engine.
All meaningful latch analysis happens by latch class in sys.dm_os_latch_stats, which groups the modes together anyway; the class identifies the contended subsystem, which is the only actionable fact latching offers.
Common Causes
- None in practice; the mode is a placeholder.
What To Do
- Nothing. If latch contention is your actual topic, work from the latch classes and the real modes (
SH,UP,EX).
How To See It
Rank waits with Get-WaitStatistics; expect a permanent zero for this one.
LATCH_NL is background noise on a healthy instance. If you are chasing a real problem, start with the waits that actually cost you time.
- The waits that usually matter, ranked, with what each one is telling you.
- Performance & Troubleshooting, the scripts and guides for this part of the stack.
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