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_BU?

1 Answer


Occurs when a task is waiting to acquire a Bulk Update (BU) lock. Information from Microsoft®

Very rare

This wait never occurs for most instances

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

Prevalence of LCK_M_BU across the Spotlight Population

For 64 % of hours with this wait, average wait time is less than 130 ms

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

45 instances contributed data to this chart

Latency Distribution of LCK_M_BU across the Spotlight Population