Lock wait events occur when a session attempts to acquire a lock that is already held by another session. A session will be blocked until the blocking session releases the lock. Locks are designed to ensure data integrity by limiting simultaneous data access.
Multi-user database locking generally consists of two levels: exclusive locks and share locks. You want to watch out for exclusive locks (that is, TX) as they prohibit resource sharing. For example, the first transaction that exclusively locks a resource is the only one that can alter the resource (except for the DBA) until the exclusive lock is released. Share locks, unlike exclusive locks, allow a resource to be shared.
A metric is an individual piece of information that Foglight for Oracle collects about the performance of a system. The information may be a numeric value (a number or percentage), a string of text, or some other piece of data.
Every time the Foglight for Oracle dashboard is refreshed, the cartridge retrieves the latest value of the metric, which can then be displayed in a drilldown or on the home page.
Network performance, which is measured in number (per second) of packets sent and received, can be used just like disk statistics to detect overload or non-optimal performance within a network or a network interface. For more information, see .