enq: PS - contention
Enqueue wait. Parallel slave synchronisation.
Disclaimer
The terms master and slave have historically been used by vendors in database wait events. DBmarlin does not support or condone the use of these terms. As vendors remove these terms from their software, occurrences will reduce.
Additional Information
An enqueue is a wait for a resource held by another. There is little documentation around this wait, but is parallel queries, the query coordinator (QC) uses a number of workers to perform the query. This is seen when the query QC is attempting to allocate workers for it’s use.
How to reduce this wait
Ensure the parallel query configuration has enough resources allocated without overloading the server.
Additional Links
Oracle Docs - VLDB and Partitioning Guide - Using Parallel Execution
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