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


2 Answers


Occurs when a query memory request cannot be granted immediately due to other concurrent queries. High waits and wait times may indicate excessive number of concurrent queries, or excessive memory request amounts. Information from Microsoft®


Used to indicate a worker is waiting to be allowed to perform an operation requiring "query memory" such as hashes and sorts.

Very rare

This wait never occurs for most instances

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

Prevalence of RESOURCE_SEMAPHORE across the Spotlight Population

For 80 % of hours with this wait, average wait time is less than 23 seconds

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

325 instances contributed data to this chart

Latency Distribution of RESOURCE_SEMAPHORE across the Spotlight Population