Oracle 视图 DBA_HIST_LATCH 官方解释，作用，如何使用详细说明
本站中文解释
Oracle 视图 DBA_HIST_LATCH 是基于 Oracle 数据库实例几小时的信息，用来收集闩的当前和历史信息，用来对数据库的状况t进行更加深入的研究和分析。
空（empty）闩是指闩可用但没有任何等待，已获取闩是指一个进程正在等待一个闩，还有一种情况是已偏好闩，正等待一个空闩。
通过使用DBA_HIST_LATCH视图可以根据一定的参数访问空闩和已获取闩的数量以及历史信息，以了解数据库实例几小时的闩获取和使用信息。它还可以帮助开发人员了解特定的等待闩的佳做法，以便改善应用程序的性能。另外它可以指导DBA，允许他们检查和监测他们的数据库，以确保最佳状况。
官方英文解释
DBA_HIST_LATCH displays historical aggregate latch statistics for both parent and child latches, grouped by latch name.
This view contains snapshots of V$LATCH.
| Column | Datatype | NULL | Description |
|---|---|---|---|
|
|
|
|
Unique snapshot ID |
|
|
|
|
Database ID for the snapshot |
|
|
|
|
Instance number for the snapshot |
|
|
|
|
Latch hash |
|
|
|
|
Latch name |
|
|
|
Latch level |
|
|
|
|
Number of times the latch was requested in willing-to-wait mode |
|
|
|
|
Number of times the latch was requested in willing-to-wait mode and the requester had to wait |
|
|
|
|
Number of times a willing-to-wait latch request resulted in a session sleeping while waiting for the latch |
|
|
|
|
Number of times a latch was requested in no-wait mode |
|
|
|
|
Number of times a no-wait latch request did not succeed (that is, missed) |
|
|
|
|
Number of willing-to-wait latch requests which missed the first try but succeeded while spinning |
|
|
|
|
These columns have been deprecated and are present only for compatibility with previous releases of Oracle. No data is accumulated for these columns; they will always have a value of zero. |
|
|
|
|
Elapsed time spent waiting for the latch (in microseconds) |
|
|
|
|
The database ID of the PDB for the sampled session |
|
|
|
|
The ID of the container that
|
See Also:
“V$LATCH”
