Shulou(Shulou.com)05/31 Report--

Oracle waits for the analysis of event type wait_class, and it is believed that many inexperienced people are at a loss about it. Therefore, this paper summarizes the causes and solutions of the problem. Through this article, I hope you can solve this problem.

The waiting event of Oracle is an important basis and index to measure the running status of the database.

There are two main types of wait events, namely idle wait events and non-idle wait events.

1, idle wait event

It means that Oracle is waiting for some kind of work, such as logging in with sqlplus, but does not issue any further commands. At this time, the session is in the state of SQL*Net message from/to client waiting for events and waiting for users to issue commands. We do not need to pay too much attention to these events when diagnosing and optimizing the database.

2, non-idle wait event

Specifically for Oracle activities, refers to the database tasks or applications running during the wait, these waiting events are we should pay attention to and study when adjusting the database.

Each wait event belongs to a certain category, and a description of each type of wait event is given below.

Management class: Administrative

Such wait events are caused by DBA administrative commands that require the user to wait, for example, to rebuild the index. [Waits resulting from DBA commands that cause users to wait (for example, an index rebuild)]

Application class: Application

Such wait events are caused by the code of the user's application (for example, lock wait) [Waits resulting from user application code (for example, lock waits caused by row level locking or explicit lock commands)]

Cluster class: Cluster

Such wait events are related to the resources that actually apply the cluster RAC. (for example, gc cr block busy wait event) [Waits related to Real Application Cluster resources (for example, global cache resources such as'gc cr block busy']

Submit confirmation class: Commit

This type of wait event contains only one wait event-after executing a commit command, wait for a redo log write confirmation (that is, log file sync) [This wait class only comprises one wait event-wait for redo log write confirmation after a commit (that is, 'log file sync')]

Concurrent class: Concurrency

Such wait events are caused by internal database resources, such as latches. [Waits for internal database resources (for example, latches)]

Configuration class: Configuration

Such wait events are caused by improper configuration of the database or instance, such as the small size of the redo log file, the size of the shared pool, and so on. [Waits caused by inadequate configuration of database or instance resources (for example, undersized log file sizes, shared pool size)]

Free class: Idle

This kind of wait event means that the session is inactive and waiting for work. For example, sql * net messages from client. [Waits that signify the session is inactive, waiting for work (for example, 'SQL*Net message from client')]

Network class: Network

Some wait events related to the network environment, such as sql* net more data to dblink. [Waits related to network messaging (for example, 'SQL*Net more data to dblink')]

Other classes: Other

Such wait events are usually rare. [Waits which should not typically occur on a system (for example, 'wait for EMON to spawn')]

Scheduling class: Scheduler

Resource Manager related waits (for example, 'resmgr: become active')

System I _ peg O class: System I _ Band O

This kind of wait event is caused by the background process's I _ db file paralle write O operation, such as DBWR wait, wait. [Waits for background process IO (for example, DBWR wait for'db file parallel write')]

User iMaple O class: User iMaple O

This type of wait event is usually caused by a user Imax O operation, such as db file sequential read. [Waits for user IO (for example'db file sequential read')]

After reading the above, have you mastered the analysis method of oracle waiting event type wait_class? If you want to learn more skills or want to know more about it, you are welcome to follow the industry information channel, thank you for reading!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.