(1)If you set CURSOR_SHARING, then Oracle recommends the FORCE setting unless you are in a DSS environment. FORCE limits the growth of child cursors that can occur when the setting is SIMILAR. (2)The value of th
(2)The value of the CURSOR_SHARING parameter has performance implications. Refer to Oracle Database Performance Tuning Guide before setting this parameter. 1.2 When to Set CURSOR_SHARING to a Nondefault Value The best practice is to write sharable SQL and use the default of EXACT for CURSOR_SH...
(1)If you set CURSOR_SHARING, then Oracle recommends the FORCE setting unless you are in a DSS environment. FORCE limits the growth of child cursors that can occur when the setting is SIMILAR. (2)The value of the CURSOR_SHARING parameter has performance implications. Refer toOracle Database ...
Allows the creation of a new cursor if sharing an existing cursor, or if the cursor plan is not optimal. EXACT Only allows statements with identical text to share the same cursor. See Also: Oracle Database SQL Tuning Guidebefore setting theCURSOR_SHARINGparameter to learn about the performance...
Oracle绑定变量详解 http://blog.csdn.net/xujinyang/article/details/6832627 二.测试 2.1 cursor_sharing=exact,这是cursor_sharing的默认值 2.1.1查看cursor_sharing值 SYS@anqing2(rac2)> show parameter cursor_sharing NAMETYPEVALUE --- --- --- cursor_sharingstringEXACT 2.1.2查看当前硬解析值 SYS@anqi...
The value of theCURSOR_SHARINGparameter has performance implications. Refer toOracle Database Performance Tuning Guidebefore setting this parameter. cursor_sharing 参数有三个值可选,exact、similar、force。 如果参数值为 exact (Oracle默认方式),当一个 statement parse 的时候,首先到 shared pool 区查看是否...
Oracle里的共享游标 Shared cursor之间的共享,就是重用存储在child cursor中的解析树和执行计划,避免不用从头开始硬解析 常用游标共享,参数cursor_sharing select * from v$parameter where name='cursor_sharing'; 839 cursor_sharing 2 EXACT Exact 默认值,Oracle不会用系统产生的绑定变量来替换目标sql的sql文本中whe...
一.自适应游标共享(Adaptive Cursor Sharing) 说明 1.1 ACS概述 绑定变量使Oracle DB 可以为多条SQL 语句共享单个游标,以减少分析SQL 语句所使用的共享内存量。然而,游标共享和SQL 优化是两个相互冲突的目标。用文字编写SQL 语句为优化程序提供了更多的信息,这无疑会导致更好的执行计划,但大量的硬分析会导致内存和...
E:\u\azure_cloud\oracle\01.png 问题基本可以推测出来是cursor等待造成的 8,验证cursor_sharing参数为EXACT,正常 SQL> show parameter cursor_sharing; NAME TYPE VALUE --- --- --- cursor_sharing string EXACT SQL> 9,查看4月28日今天的记录数是35W多,而且这个执行次数还在不停的增加中 ...
一.AdaptiveCursorSharing概述在Oracle10g和11g中对绑定变量的处理，已经有所不同，在Oracle10g中，绑定变量相对比较简单，当使用绑定变量的SQL第一次执行时，会进行硬解析，生成plan和cursor。在这个过程中，Oracle会使用bindpeeking，即将绑定变量的值带入，从而选择最优的一个plan。以后每次执行都使用这个plan。 在...