QB_NAMESpecifies a name for a query block. (from Oracle 10g) CURSOR_SHARING_EXACTOracle can replace literals in SQL statements with bind variables, if it is safe to do so. This is controlled with the CURSOR_SHARING startup parameter. The CURSOR_SHARING_EXACT hint causes this behavior to be...
Starting with kernel Release 4.6B all the above mentioned FOR ALL ENTRIES parameters can be set via such a hint for a single statement. In the example: SELECT * FROM [..] FOR ALL ENTRIES IN [..] WHERE [..] %_HINTS ORACLE '&prefer_in_itab_opt 1&&prefer_fix_blocking -1&'. This...
It is a perfect valid question to ask why hints should be used. Oracle comes with anoptimizerthat promises to optimize aquery's execution plan. When this optimizer is really doing a good job, no hints should be required at all. Sometimes, however, the characteristics of the data in the d...
SELECT /*+USE_HASH(emp,dept)*/ * FROM emp,dept WHERE emp.deptno=dept.deptno;
假设你没有正确的指定Hints,Oracle将忽略该Hints,而且不会给出不论什么错误。 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. 比如: SELECT /*+ALL+_ROWS*/ EMP_NO,EMP_NAM,DAT_IN FROM BSEMPMS WHERE EMP_NO=’SCOTT’; 2. /*+FIRST_ROWS*/ 表明对语...
文本概述: Oracle Hints是一种机制,允许DBA干预优化器生成执行计划,以解决优化器选择低效执行计划的问题。通过Hints,可以控制优化器的类型、优化目标、访问路径、连接类型、连接顺序和并行程度等。Hints通过特定格式的注释添加到SQL语句中,且只作用于所在语句块。正确使用Hints可以显著提高查询或DML操作的效率,但需定期分析...
为了不破坏 SQL 的兼容性,采用了 Oracle 形式的 SQL hint 语法: ```sql table_path /+ OPTIONS(key=val [, key=val]) */ key: stringLiteral val: stringLiteral # 示例```sql CREATE TABLE kafka_table1 (id BIGINT, name STRING, age INT) WITH (...); ...
如果你没有正确的指定Hints,Oracle将忽略该Hints,并且不会给出任何错误。 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_IN FROM BSEMPMS WHERE EMP_NO='SCOTT'; ...
如果你没有正确的指定Hints,Oracle将忽略该Hints,并且不会给出任何错误。 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_IN FROM BSEMPMS WHERE EMP_NO='SCOTT'; ...
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