ClientRead

Waiting to read/hear from the client/application. This is the server time wasted without processing anything at the server side. Big precentage of this wait-event indicates response from application is not fast enough, DB server is wasting its processing power waiting for the application to respond. Two reasons generally cause high values for this wait-event

1. Network :

The communication channel between the database and the application/client may have low bandwith or high latency. For example, there could be too many network hops. Many of the Cloud, Virtualization, Containerization, Firewall, and Routing (sometimes multi-layer routing) are found to cause high network latency. Latency has nothing to do with network bandwidth. Even a very high bandwidth connection can have high latency and affect the database performance. The network related waits within the trasactions are generally accounted as "ClientRead"

2. Application response:

The application side might be taking too long to respond to the database. For example, a transaction in progress might not be sending a COMMIT or ROLLBACK fast enough after sending the DML to the database server. This "ClientRead" wait-event combined with "idle-in-transaction" can cause contention in the server.