Oracle相当于Postgres EXPLAIN ANALYZE

Question

类似于this question。

我想在Oracle（10g）中得到一个详细的查询计划和实际执行，类似于PostgreSQL中的EXPLAIN ANALYZE。有没有相同的东西？

Answer 1

最简单的方法是sql * plus中的autotrace。

SQL> set autotrace on exp 
SQL> select count(*) from users ; 

    COUNT(*) 
---------- 
    137553 


Execution Plan 
---------------------------------------------------------- 
    0  SELECT STATEMENT Optimizer=ALL_ROWS (Cost=66 Card=1) 
    1 0 SORT (AGGREGATE) 
    2 1  INDEX (FAST FULL SCAN) OF 'SYS_C0062362' (INDEX (UNIQUE) 
     ) (Cost=66 Card=137553) 

或者，甲骨文确实有一个explain plan声明，你可以执行，然后查询各种计划表。最简单的方法是使用DBMS_XPLAN包：

SQL> explain plan for select count(*) from users ; 

Explained. 
SQL> SELECT * FROM table(DBMS_XPLAN.DISPLAY); 

-------------------------------------------------------------- 
| Id | Operation    | Name   | Rows | Cost | 
-------------------------------------------------------------- 
| 0 | SELECT STATEMENT  |    |  1 | 66 | 
| 1 | SORT AGGREGATE  |    |  1 |  | 
| 2 | INDEX FAST FULL SCAN| SYS_C0062362 | 137K| 66 | 
-------------------------------------------------------------- 

如果你是老学校，你可以查询计划表自己：

SQL> explain plan set statement_id = 'my_statement' for select count(*) from users; 

Explained. 

SQL> column "query plan" format a50 
SQL> column object_name format a25 
SQL> select lpad(' ',2*(level-1))||operation||' '||options "query plan", object_name 
from plan_table 
start with id=0 and statement_id = '&statement_id' 
connect by prior id=parent_id 
    and prior statement_id=statement_id 
Enter value for statement_id: my_statement 
old 3: start with id=0 and statement_id = '&statement_id' 
new 3: start with id=0 and statement_id = 'my_statement' 

SELECT STATEMENT 
    SORT AGGREGATE 
    INDEX FAST FULL SCAN       SYS_C0062362 

甲骨文使用一个实用程序文件utlxpls.sql是有出货该查询的更完整版本。请检查$ORACLE_HOME/rdbms/admin。

对于任何这些方法，您的DBA必须已经设置了适当的计划表。