强制归档参数ARCHIVE_LAG_TARGET

最新推荐文章于 2021-04-03 06:07:55 发布

转载最新推荐文章于 2021-04-03 06:07:55 发布 · 397 阅读

本文详细介绍了在Standby环境中使用ARCHIVE_LAG_TARGET参数的方法。通过设置此参数，可以有效减少因故障导致的数据丢失，并提高备用数据库的可用性。推荐的值为1800秒（30分钟），过小的值可能会导致性能下降。

在Standby 环境中，为了减少出现故障时数据损失，我们可以设置ARCHIVE_LAG_TARGET参数，强制进行日志切换。ARCHIVE_LAG_TARGET参数可以设置一个时间，通过时间限制，指定数据库强制进行Log Switch，进行归档。这个参数的缺省值是0，即为不启用该参数。该参数合理的取值范围在60 ~ 7200之间。通常大于7200和小于1800不被推荐，低于30分钟的切换时间可能导致性能问题。

ARCHIVE_LAG_TARGET

Property	Description
Parameter type	Integer
Default value	0 (disabled)
Modifiable	ALTER SYSTEM
Range of values	0 or any integer in [60, 7200]
Basic	No
Real Application Clusters	Multiple instances should use the same value.

ARCHIVE_LAG_TARGET limits the amount of data that can be lost and effectively increases the availability of the standby database by forcing a log switch after the specified amount of time elapses.

A 0 value disables the time-based thread advance feature; otherwise, the value represents the number of seconds. Values larger than 7200 seconds are not of much use in maintaining a reasonable lag in the standby database. The typical, or recommended value is 1800 (30 minutes). Extremely low values can result in frequent log switches, which could degrade performance; such values can also make the archiver process too busy to archive the continuously generated logs.

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