Waitopedia is a comprehensive resource of information about SQL Server waits.

The description shown below is the top answer as voted by the Spotlight community.

The charts are based on 2.1 TB of data collected from 4207 instances uploaded by 323 Spotlight users over an 8 week period.


Category: Lock
SQL Server versions: 2000, 2005, 2008, 2008 R2, 2012, 2014, 2016, 2017

What is LCK_M_RS_U?

1 Answer


Occurs when a task is waiting to acquire an Update lock on the current key value, and an Update Range lock between the current and previous key. Information from Microsoft®

Very rare

This wait never occurs for most instances

For each of 4207 instances, we ranked LCK_M_RS_U on how frequent it is compared to all other recent waits. The chart shows the total of all rankings.

Prevalence of LCK_M_RS_U across the Spotlight Population

For 81 % of hours with this wait, average wait time is less than 89 ms

For each instance, we found all the recent hours when it had a LCK_M_RS_U wait. We found the average latency for each of those hours.

432 instances contributed data to this chart

Latency Distribution of LCK_M_RS_U across the Spotlight Population