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Oracle Kernel : Function kglic & Library Cache Latch
作者：eygle | 【转载请注出处】|【云和恩墨 领先的zData数据库一体机 | zCloud PaaS云管平台 | SQM SQL审核平台 | ZDBM 数据库备份一体机】
链接：https://www.eygle.com/archives/2012/09/oracle_kernel_kglic.html
最近在客户的一个案例中，遇到Latch : Library Cache的竞争，其竞争位于kglic函数调用。链接：https://www.eygle.com/archives/2012/09/oracle_kernel_kglic.html
以下是关于KGLIC函数的功能简要说明：
1. kglic means Kernel Generic Library cache Iterate Chain (AFAIK), it's the function which is executed when you access most X$KGL tables.
2. kglic is the code which goes through the library cache and row cache to answer queries on various dictionary fixed views and tables. This is the function which returns data for the fixed views and tables that scan the sql area. Therefore, it was highly possible that such queries could also be coming from monitoring tools used by DBAs and they are not restricted to the two views specifically mentioned in the bug by Joan. Any monitoring job which looks at v$open_cursor would also use the kglic iterator.
与此相关的BUG，在10g中仍然存在，最后确认客户有较为频繁的查询访问v$sql视图，导致了严重的library cache的竞争。
以下BUG的影响版本为10.2.0.4，10.2.0.5，11.2.0.2 ：
Bug 9287616 - Accessing [G]V$SQL or [G]V$SQLTEXT_WITH_NEWLINES may be slow / takes a long time / latch contention (Doc ID 9287616.8)
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By eygle on 2012-09-19 08:27 | Comments (0) | Internal | 3046 |