We have a statement based replication server that has been experiencing slowdowns and during the event
SHOW FULL PROCESSLIST showed the replication query stuck on
"Waiting for query cache lock" which was surprising because the server
query_cache_size is set to
Profiling the offending query does show this step in every update to the table.
Is this typical to see in the profile for an update even if the
0? Is this really just the check for query caching and not the query waiting to obtain a true lock?