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This article mainly explains "which two kinds of statistics_level parameters of the database". The content of the explanation in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "which two kinds of statistics_level parameters of the database".

There are two kinds of parameters about statistics_level: alter session,alter system.

PropertyDescriptionParameter typeStringSyntaxSTATISTICS_LEVEL = {ALL | TYPICAL | BASIC} Default valueTYPICALModifiableALTER SESSION, ALTER SYSTEM

STATISTICS_LEVEL specifies the level of collection of database and operating system statistics. The Oracle database collects these statistics for a variety of purposes, including making self-management decisions.

The default setting of TYPICAL ensures that all the key statistics required for the self-management of the database are collected and provides the best overall performance. For most environments, the default value should be sufficient.

When the STATISTICS_LEVEL parameter is set to ALL, other statistics are added to the set of TYPICAL settings with the collected statistics. Other statistics are timing operating system statistics and plan execution statistics

Set the STATISTICS_LEVEL parameter to BASIC to disable the collection of many important statistics required for Oracle database features and functions, including:

1 automatic workload Repository (AWR) Snapshot

2 automatic database diagnostic monitor (ADDM)

3 Alerts generated by all servers

4 automatic SGA memory management

5 automatic optimizer statistics collection

6 object-level statistics

7 end-to-end application tracking (V$CLIENT_STATS)

8 Database time distribution statistics (V$SESS_TIME_MODEL and V$SYS_TIME_MODEL)

9 Service level statistics

10 buffer cache consultation

11MTTR consultation

12 shared pool sizing consultation

13 Breakdown level statistics

14PGA goal consultation

15 timing statistics

16 Monitoring statistics

And oracle strongly recommends that you do not disable these important features.

When the STATISTICS_LEVEL parameter is modified ALTER SYSTEM, all announcements or statistics are dynamically turned on or disconnected, depending on the new value STATISTICS_LEVEL. When ALTER SESSION is modified, the following recommendations or statistics are turned on or off only in the local session. Their system-wide state has not changed:

1. Timing statistics

two。 Timing operating system statistics

3. Plan execution statistics

The V$STATISTICS_LEVEL view displays information about statistics or recommended status controlled by the STATISTICS_LEVEL parameter.

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