The percentage of concurrency. Concurrency is a database behavior when different transactions request to change the same resource. In the case of modifying data transactions, it sequentially temporarily blocks the right to change the data, and the rest of the transactions wait for access. When the access to a resource is locked for a long time, the concurrency grows (like the transaction queue), often leaving an extremely negative impact on performance. A high contention value does not indicate the root cause of the problem, but is a signal to search for it.