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Foglight for Oracle (Cartridge) 6.1.0.10 - User Guide

Installing and Configuring Agents Using Foglight for Oracle
Viewing the Databases Dashboard Assigning Instances to Users Selecting an Instance to Monitor Foglight for Oracle Overview Dashboard Overview view Advisories view SQL Performance Investigator (SQL PI) Oracle Activity Drilldown Pluggable Databases Drilldown Storage Drilldown Reviewing Configuration Settings Reviewing the Alert Log Reviewing Monitored Data Guard Environments Reviewing ASM Instances Reviewing Exadata-related Information
Administering Foglight for Oracle Reporting Reference Glossary

Lock Wait

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.

Most locking issues are application-specific and can be addressed by tuning the concurrency logic in the application.

Logical Reads

The number of data blocks read by Oracle, which were already present in the buffer cache, thereby saving input/output read operations.

This value is also referred to as session logical reads and is the total of Current Reads plus Consistent Reads.

Metric

A unit of measurement that can be applied to a database. Metrics can help gauge the performance of a system.

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 Wait

Network wait events occur when a session spends time waiting for messages to be sent or received over the network interface.

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 SQL *net.

Excessive network wait can result from either:

•
Excessive network usage, originating in the application
•
Physical issues, identifiable by network errors and network collisions
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