library cache latch等待事件

This latch serializes access to the objects in the library cache. Every time a SQL statement, a PL/SQL block or a stored object (procedure, package, function, trigger) is parsed or executed, this latch is acquired.

Problem - Fragmentation of the shared pool

Excessive execution of a statement can cause library cache contention.

Many versions of one SQL statement in the shared pool

Excessive parsing of SQL statements (even soft parsing) because of non-reusable queries or large objects being loaded in the shared pool forcing out the smaller heavily used queries

Solutions

Use bind variables whenever possible. Reuse of code means less parsing and less use of shared pool space.

Pin packages and procedures that are heavily executed in the shared pool. This prevents the heavily used code from being flushed out and thus needing to be parsed in.

Increase SESSION_CACHED_CURSORS parameter. This helps if the user repeatedly parses the same statements.

Use fully qualified table names. Example: "select * from owner.table" instead of "select * from table"

If using EXECUTE IMMEDIATE with bind variables, try using DBMS_SQL instead.

If the statement is complex and heavily executed, the load on the library cache could be reduced by breaking it up into multiple smaller statements.

Reducing the versions of SQL statements reduces the load on library cache as well. Oracle deals with various bind variable sizes by creating multiple versions of the statement. One possible solution would be writing more smaller queries rather than one large one.

Specify objects over a certain size be loaded into the large pool instead of the shared pool.

It's possible that the shared pool is too small. If the above remedies have been attempted and contention is still evident, look into increasing the shared pool gradually.

Please also refer to Oracle's MetaLink's Note:146599.1 for information on this latch.

?著作權歸作者所有：來自51CTO博客作者maclean_007的原創作品，如需轉載，請注明出處，否則將追究法律責任

總結

以上是生活随笔為你收集整理的oracle 父latch:library cache,library cache latch等待事件的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。