leading--Oracle hint
SQL> explain plan for select rowid rid from
2 scott.emp e where e.empno >100 and e.empno < 1000 and e.deptno in (select deptno from scott.dept where dname like 'a%');
已解释。
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY(NULL, NULL, 'ADVANCED -PROJECTION'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 1465018025 -----------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 32 | 3 (0)| 00:00:01 |
| 1 | NESTED LOOPS | | | | | |
| 2 | NESTED LOOPS | | 1 | 32 | 3 (0)| 00:00:01 |
| 3 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 19 | 2 (0)| 00:00:01 |
|* 4 | INDEX RANGE SCAN | PK_EMP | 1 | | 1 (0)| 00:00:01 |
|* 5 | INDEX UNIQUE SCAN | PK_DEPT | 1 | | 0 (0)| 00:00:01 |
|* 6 | TABLE ACCESS BY INDEX ROWID | DEPT | 1 | 13 | 1 (0)| 00:00:01 |
----------------------------------------------------------------------------------------- Query Block Name / Object Alias (identified by operation id):
------------------------------------------------------------- 1 - SEL$5DA710D3
3 - SEL$5DA710D3 / E@SEL$1
4 - SEL$5DA710D3 / E@SEL$1
5 - SEL$5DA710D3 / DEPT@SEL$2
6 - SEL$5DA710D3 / DEPT@SEL$2 Outline Data
------------- /*+
BEGIN_OUTLINE_DATA
NLJ_BATCHING(@"SEL$5DA710D3" "DEPT"@"SEL$2")
USE_NL(@"SEL$5DA710D3" "DEPT"@"SEL$2")
LEADING(@"SEL$5DA710D3" "E"@"SEL$1" "DEPT"@"SEL$2")
INDEX(@"SEL$5DA710D3" "DEPT"@"SEL$2" ("DEPT"."DEPTNO"))
INDEX_RS_ASC(@"SEL$5DA710D3" "E"@"SEL$1" ("EMP"."EMPNO"))
OUTLINE(@"SEL$2")
OUTLINE(@"SEL$1")
UNNEST(@"SEL$2")
OUTLINE_LEAF(@"SEL$5DA710D3")
ALL_ROWS
DB_VERSION('11.2.0.1')
OPTIMIZER_FEATURES_ENABLE('11.2.0.1')
IGNORE_OPTIM_EMBEDDED_HINTS
END_OUTLINE_DATA
*/ Predicate Information (identified by operation id):
--------------------------------------------------- 4 - access("E"."EMPNO">100 AND "E"."EMPNO"<)
5 - access("E"."DEPTNO"="DEPTNO")
6 - filter("DNAME" LIKE 'a%')
已选择50行。
SQL> explain plan for select /*+leading(DEPT@SEL$2)*/rowid rid from
2 scott.emp e where e.empno >100 and e.empno < 1000 and e.deptno in (select deptno from scott.dept where dname like 'a%');
已解释。
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY(NULL, NULL, 'ADVANCED -PROJECTION'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 817787759 -----------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 32 | 5 (20)| 00:00:01 |
| 1 | MERGE JOIN | | 1 | 32 | 5 (20)| 00:00:01 |
|* 2 | TABLE ACCESS BY INDEX ROWID | DEPT | 1 | 13 | 2 (0)| 00:00:01 |
| 3 | INDEX FULL SCAN | PK_DEPT | 4 | | 1 (0)| 00:00:01 |
|* 4 | SORT JOIN | | 1 | 19 | 3 (34)| 00:00:01 |
| 5 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 19 | 2 (0)| 00:00:01 |
|* 6 | INDEX RANGE SCAN | PK_EMP | 1 | | 1 (0)| 00:00:01 |
----------------------------------------------------------------------------------------- Query Block Name / Object Alias (identified by operation id):
------------------------------------------------------------- 1 - SEL$5DA710D3
2 - SEL$5DA710D3 / DEPT@SEL$2
3 - SEL$5DA710D3 / DEPT@SEL$2
5 - SEL$5DA710D3 / E@SEL$1
6 - SEL$5DA710D3 / E@SEL$1 Outline Data
------------- /*+
BEGIN_OUTLINE_DATA
USE_MERGE(@"SEL$5DA710D3" "E"@"SEL$1")
LEADING(@"SEL$5DA710D3" "DEPT"@"SEL$2" "E"@"SEL$1")
INDEX_RS_ASC(@"SEL$5DA710D3" "E"@"SEL$1" ("EMP"."EMPNO"))
INDEX(@"SEL$5DA710D3" "DEPT"@"SEL$2" ("DEPT"."DEPTNO"))
OUTLINE(@"SEL$2")
OUTLINE(@"SEL$1")
UNNEST(@"SEL$2")
OUTLINE_LEAF(@"SEL$5DA710D3")
ALL_ROWS
DB_VERSION('11.2.0.1')
OPTIMIZER_FEATURES_ENABLE('11.2.0.1')
IGNORE_OPTIM_EMBEDDED_HINTS
END_OUTLINE_DATA
*/ Predicate Information (identified by operation id):
--------------------------------------------------- 2 - filter("DNAME" LIKE 'a%')
4 - access("E"."DEPTNO"="DEPTNO")
filter("E"."DEPTNO"="DEPTNO")
6 - access("E"."EMPNO">100 AND "E"."EMPNO"<) 已选择50行。
SQL> explain plan for select /*+leading(DEPT)*/rowid rid from
2 scott.emp e where e.empno >100 and e.empno < 1000 and e.deptno in (select deptno from scott.dept where dname like 'a%');
已解释。
SQL> SELECT * FROM TABLE(DBMS_XPLAN.DISPLAY(NULL, NULL, 'ADVANCED -PROJECTION'));
PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------------------------------------------
Plan hash value: 817787759 -----------------------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
-----------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 32 | 5 (20)| 00:00:01 |
| 1 | MERGE JOIN | | 1 | 32 | 5 (20)| 00:00:01 |
|* 2 | TABLE ACCESS BY INDEX ROWID | DEPT | 1 | 13 | 2 (0)| 00:00:01 |
| 3 | INDEX FULL SCAN | PK_DEPT | 4 | | 1 (0)| 00:00:01 |
|* 4 | SORT JOIN | | 1 | 19 | 3 (34)| 00:00:01 |
| 5 | TABLE ACCESS BY INDEX ROWID| EMP | 1 | 19 | 2 (0)| 00:00:01 |
|* 6 | INDEX RANGE SCAN | PK_EMP | 1 | | 1 (0)| 00:00:01 |
----------------------------------------------------------------------------------------- Query Block Name / Object Alias (identified by operation id):
------------------------------------------------------------- 1 - SEL$5DA710D3
2 - SEL$5DA710D3 / DEPT@SEL$2
3 - SEL$5DA710D3 / DEPT@SEL$2
5 - SEL$5DA710D3 / E@SEL$1
6 - SEL$5DA710D3 / E@SEL$1 Outline Data
------------- /*+
BEGIN_OUTLINE_DATA
USE_MERGE(@"SEL$5DA710D3" "E"@"SEL$1")
LEADING(@"SEL$5DA710D3" "DEPT"@"SEL$2" "E"@"SEL$1")
INDEX_RS_ASC(@"SEL$5DA710D3" "E"@"SEL$1" ("EMP"."EMPNO"))
INDEX(@"SEL$5DA710D3" "DEPT"@"SEL$2" ("DEPT"."DEPTNO"))
OUTLINE(@"SEL$2")
OUTLINE(@"SEL$1")
UNNEST(@"SEL$2")
OUTLINE_LEAF(@"SEL$5DA710D3")
ALL_ROWS
DB_VERSION('11.2.0.1')
OPTIMIZER_FEATURES_ENABLE('11.2.0.1')
IGNORE_OPTIM_EMBEDDED_HINTS
END_OUTLINE_DATA
*/ Predicate Information (identified by operation id):
--------------------------------------------------- 2 - filter("DNAME" LIKE 'a%')
4 - access("E"."DEPTNO"="DEPTNO")
filter("E"."DEPTNO"="DEPTNO")
6 - access("E"."EMPNO">100 AND "E"."EMPNO"<) 已选择50行。
leading--Oracle hint的更多相关文章
- SWAP_JOIN_INPUTS Oracle Hint(处理hash join强制大表（segment_size大）作为被驱动表)
SWAP_JOIN_INPUTS Oracle Hint(处理hash join强制大表(segment_size大)作为被驱动表) swap_join_inputs是针对哈希连接的hint,它的含义 ...
- SQL优化过程中常见Oracle HINT
在SQL语句优化过程中,我们经常会用到hint,现总结一下在SQL优化过程中常见Oracle HINT的用法: 1. /*+ALL_ROWS*/ 表明对语句块选择基于开销的优化方法,并获得最佳吞吐量, ...
- Oracle hint手动优化
例子 select/*+FULL(fortest)*/ * from fortest where id = 2000000 //使用0.70s时间 select* from fortest where ...
- 品味性能之道<十>：Oracle Hint
Hint 是Oracle 提供的一种SQL语法,它允许用户在SQL语句中插入相关的语法,从而影响SQL的执行方式. 因为Hint的特殊作用,所以对于开发人员不应该在代码中使用它,Hint 更像是Ora ...
- Oracle Hint 详解
Hint 是Oracle 提供的一种SQL语法,它允许用户在SQL语句中插入相关的语法,从而影响SQL的执行方式. 因为Hint的特殊作用,所以对于开发人员不应该在代码中使用它,Hint 更像是Ora ...
- oracle --hint总结
得到一条sql语句执行计划的常用方法:1.explain plan 命令 2.DBMS_XPLAN包3.sqlplus中的AUTOTRACE开关4.10046事件5.10053事件6.AWR报告或者 ...
- 【DBAplus】SQL优化：一篇文章说清楚Oracle Hint的正确使用姿势
原创 2016-09-12 韩锋 作者介绍 韩锋,宜信技术研发中心数据库架构师.精通多种关系型数据库,曾任职于当当网.TOM在线等公司,曾任多家公司首席DBA.数据库架构师等职,多年一线数据库架构. ...
- SQL优化：一篇文章说清楚Oracle Hint的正确使用姿势
一.提示(Hint)概述 1为什么引入Hint? Hint是Oracle数据库中很有特色的一个功能,是很多DBA优化中经常采用的一个手段.那为什么Oracle会考虑引入优化器呢?基于代价的优化器是很聪 ...
- 常见Oracle HINT的用法
1. /*+ALL_ROWS*/ 表明对语句块选择基于开销的优化方法,并获得最佳吞吐量,使资源消耗最小化. 例如: SELECT /*+ALL+_ROWS*/ EMP_NO,EMP_NAM,DAT_I ...
- Oracle Hint 用法
正确的语法是: select /*+ index(x idx_t) */ * from t x where x.object_id=123 /*+ */ 和注释很像,比注释多了一个“+”,这就是 ...
随机推荐
- 使用ggbio在R中制作弦图
分享一个制作弦图的R包:ggbio. 以下是一个简单的使用实例,效果图和代码如下. library(GenomicRanges) set.seed(1) N <- 100 gr <- GR ...
- (转)MySQL 常用数据存储引擎区别
MySQL 常用数据存储引擎区别 原文:https://laravel-china.org/articles/4198/mysql-common-data-storage-engine mysql有多 ...
- 【Canal源码分析】Canal Server的启动和停止过程
本文主要解析下canal server的启动过程,希望能有所收获. 一.序列图 1.1 启动 1.2 停止 二.源码分析 整个server启动的过程比较复杂,看图难以理解,需要辅以文字说明. 首先程序 ...
- Zookeeper--0100--简介说明
1.1-Zookeeper简介 什么是Zookeeper? Zookeeper是一个高效的分布式协调服务,它暴露了一些公共服务,比如命名/配置/管理/同步控制/群组服务等.我们可以使用ZK来实现比如达 ...
- Javac语法糖之Enum类
枚举类在Javac中是被当作类来看待的. An enum type is implicitly final unless it contains at least one enum constant ...
- mybatis异常：Error instantiating class com.psc.bean.User with invalid types () or values ().
Error instantiating class com.psc.bean.User with invalid types () or values (). 是由于bean类没有无参构建方法,添加一 ...
- ABP实战--项目结构
学习完毕With ASP.NET Core & Entity Framework Core Part-1及Part-2后,只实现了基本的功能,使用该工程继续学习ABP的更多功能. 更改项目结构 ...
- json-lib使用——JSONObject与JSONArray
ps:看这篇博客之前首先要引入工具包json-lib-2.2.2-jdk15.jar 资源链接:百度云:链接:https://pan.baidu.com/s/1o9k7PSu 密码:00lj 一.从O ...
- shell:syntax error:unexpected end of file/Starting proxy www-balancer: cannot bind socket--转载
src:http://www.2cto.com/os/201308/238962.html 执行某bash脚本是发生: syntax error: unexpected end of file 主 ...
- Tornado异步IO
Tornado提供了强大的异步IO机制,提高了服务器的响应能力. @tornado.web.asynchronous tornado默认在处理函数返回时关闭链接,@tornado.web.asynch ...