一、什么是执行计划(explain plan) 执行计划:一条查询语句在oracle中的执行过程或访问路径的描述。 二、如何查看执行计划 1.setautotraceon2.explain planforsql语句;selectplan_table_outputfromtable(dbms_xplan.display());3.通过第3方工具,如plsql developer(f5
Oracle Database generates an internal SQL statement, which in turn generates a recursive call. In short, recursive calls are basically SQL performed on behalf of your SQL. So, if you had to parse the query, for example, you might have had to run some other queries to get ...
SQL>EXPLAIN PLAN FOR sql语句; SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); 示例: SQL>EXPLAIN PLAN FOR SELECT * FROM DAVE; 已解释。 SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); 或者: SQL>select * from table(dbms_xplan.display...
一、什么是执行计划(explain plan) 执行计划:一条查询语句在oracle中的执行过程或访问路径的描述。 1. 二、如何查看执行计划 1.set autotrace on 2.explain plan for sql语句; select plan_table_output from table(dbms_xplan.display()); 3.通过第3方工具,如plsql developer(f5查看执行计划)、toad等; 1....
SQL>EXPLAIN PLAN FOR SELECT * FROM DAVE; 已解释。 SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); 或者: SQL>select * from table(dbms_xplan.display); PLAN_TABLE_OUTPUT --- Plan hash value: 3458767806 --- | Id | Operation | Name |...
SQL>EXPLAIN PLAN FOR sql语句; SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); 示例: SQL>EXPLAIN PLAN FOR SELECT * FROM DAVE; 已解释。 SQL>SELECT plan_table_output FROM TABLE(DBMS_XPLAN.DISPLAY('PLAN_TABLE')); ...
6.1ExplainPlans(解释计划)(page153) TheEXPLAINPLANstatementisusedtodisplaytheplanoperations chosenbytheoptimizerforaSQLstatement.ThefirstthingIwant toclarifyisthatwhenyouhaveEXPLAINPLANoutput,youhavethe estimatedexecutionplanthatshouldbeusedwhentheSQLstatement ...
[转]Oracle执行计划（ExplainPlan）说明 [转]Oracle执⾏计划（ExplainPlan）说明 原⽂地址:http://langgufu.iteye.com/blog/2158163 如果要分析某条SQL的性能问题，通常我们要先看SQL的执⾏计划，看看SQL的每⼀步执⾏是否存在问题。如果⼀条SQL平时执⾏的好好的，却有⼀天突然性能很差，如果排除了...
Under certain conditions the plan shown when using EXPLAIN PLAN can be different from the plan shown using V$SQL_PLAN. For example, when the SQL statement contains bind variables the plan shown from using EXPLAIN PLAN ignores the bind variable values while the plan shown in V$SQL_PLAN takes ...
一、什么是执行计划 An explain plan is a representation of the access path that is taken when a query is executed within Oracle.二、如何访问数据 At the physical level Oracle reads blocks of data. The smallest amount of data read is a single Oracle block, the largest is ...