Manual:$wgDBAvgStatusPoll

Database settings: $wgDBAvgStatusPoll
Average time between SHOW STATUS queries in overload conditions.
Introduced in version:1.12.0 (r30250)
Removed in version:1.26.0 (Gerrit change 202604; git #53acdd6b)
Allowed values:(integer)
Default value:2000

Details edit

Scale load balancer polling time so that under overload conditions, the database server receives a SHOW STATUS query at an average interval of this many microseconds.