Check the Oracle Database Licensing Guide for more information. INDEXING CHALLENGES Indexes are useful for most types of workload and particularly critical for high performance in online transaction processing (OLTP) and operational data store (ODS) environments. However, identifying the best indexes ...
Response headers as JSON data in a JSON object status_code HTTP response status code as an integer DBMS_CLOUD_OCI_OP_OPTIMIZER_GET_ENROLLMENT_STATUS_RESPONSE_T Type Contains the response body, headers and the status code of the get_enrollment_status request. ...
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production PL/SQL Release 11.2.0.3.0 - Production CORE 11.2.0.3.0 Production TNS for 64-bit Windows: Version 11.2.0.3.0 - Production NLSRTL Version 11.2.0.3.0 - Production SQL> select count(1) from joinA A where A.CUST...
oracle优化器会利用统计信息来选择最优或者次优的执行计划,在确定执行计划的过程中,oracle可以非常很好的分析每个表列的数据分布特征,但是对于列与列之间的某些关联关系,oracle是无能为力的,例如城市名称和邮编之间的对应关系。值得庆幸的是,在oracle11g中,引入了基于列组合和关系表达式的统计分析功能,这无疑为优化器做...
Oracle SQL Optimizer IN VS Exists Again 传统的SQL优化思想认为IN、Exists这2种写法不同数据量的环境中各擅胜场,Developer应当根据实际情况合理运用IN或Exists。 实际我认为,这种认识对于现代SQL优化器Optimizer(10g以后)不再适用。 CBO优化器中本身包含了查询转换(Query Transformation)的功能。 为什么CBO要做查询转换...
Types of SQL Statements Oracle optimizes these different types of SQL statements: simple statement An INSERT, UPDATE, DELETE, or SELECT statement that involves only a single table. simple query Another name for a SELECT statement. join A query that selects data from more than one table....
Oracle SQL Optimizer IN VS Exists Again 传统的SQL优化思想认为IN、Exists这2种写法不同数据量的环境中各擅胜场,Developer应当根据实际情况合理运用IN或Exists。 实际我认为,这种认识对于现代SQL优化器Optimizer(10g以后)不再适用。 CBO优化器中本身包含了查询转换(Query Transformation)的功能。 为什么CBO要做查询转换...
More information on the DBMS_XPLAN package can be found in the Oracle® Database PL/SQL Packages and Types Reference guide. 6 THE ORACLE OPTIMIZER EXPLAIN THE EXPLAIN PLAN What is Cost? The Oracle Optimizer is a cost-based optimizer. The execution plan selected for a SQL statement is just...
In Oracle Database 10g (10.2.0.4) you can use the DBMS_STATS.COPY_TABLE_STATS procedure. This procedure enables you to copy statistics from an existing [sub] partition to the new [sub] partition and will adjust statistics to account for the additional partition of data (for example the num...
in my query missing in my plan. This original post dealt with just one of the new transformations introduced in Oracle Database 11g called table elimination. Part one of our new series will deal with subquery unnesting. I must give credit to Rafi, one of the senior Optimizer developers, ...