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: Idle
SQL Server versions: 2012, 2014, 2016, 2017

This is an idle wait and so it can be safely ignored.


1 Answer


appears to relate to Cisco Unified Computing System communciations - http://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/unified-computing/whitepaper_C11-732222.html with related extended events; ucs.ucs_connection_rejected_by_proxy_whitelist – After a connection attempt to the UCS proxy endpoint is rejected by whitelist check ucs.ucs_proxy_connect_next_hop – UCS proxy next hop connection ucs.ucs_proxy_receive_proxy_connect_message – UCS proxy receive proxy connect message ucs.ucs_proxy_route_add – UCS proxy route added ucs.ucs_proxy_route_disable – UCS proxy route disabled ucs.ucs_proxy_route_refresh – UCS proxy route refreshed ucs.ucs_proxy_send_proxy_connect_message – UCS proxy send proxy connect message

Very rare

This wait never occurs for most instances

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

Prevalence of UCS_SESSION_REGISTRATION across the Spotlight Population

For 39 % of hours with this wait, average wait time is less than 0.05 ms

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

159 instances contributed data to this chart

Latency Distribution of UCS_SESSION_REGISTRATION across the Spotlight Population