04.DBMS_XPLAN 패키지

사용가능 버전 : oracle 9.2
10g부터 라이브러리 캐시에 캐싱된 SQL 커서에 대한 실행계획, Row Source별 수행통계까지도 출력 가능

(1)예상 실행계획 출력

정의


DBMS_XPLAN.DISPLAY(table_name    IN  VARCHAR2  DEFAULT 'PLAN_TABLE',
                   statement_id  IN  VARCHAR2  DEFAULT  NULL,--생략시 최근 수행 statement_id 
                   format        IN  VARCHAR2  DEFAULT 'TYPICAL',
                   filter_preds  IN  VARCHAR2  DEFAULT  NULL);

Format 옵션

옵션	표시정보
BASIC	Id, Operation, Name
TYPICAL	Id, Operation, Name, Rows, Bytes, Cost (%CPU), Time Predicate Information	ALL	Id, Operation, Name, Rows, Bytes, Cost (%CPU), Time Query Block Name / Object Alias Predicate Information Column Projection Information
OUTLINE	Id, Operation, Name, Rows, Bytes, Cost (%CPU), Time Outline Data Predicate Information
ADVANCED	Id, Operation, Name, Rows, Bytes, Cost (%CPU), Time Query Block Name / Object Alias Outline Data Predicate Information Column Projection Information
SERIAL	TYPICAL과 동일하나 병렬 수행 정보(parallel) 정보를 표시하지 않음

Query Block Name - 쿼리 블록 명칭을 보여줌
Predicate Information - 데이터 접근 방법을 보여줌
Outline Data - 실제 옵티마이저가 활용하는 힌트로써 이 정보를 이용하면 기존 힌트로 구현하기 어려운 튜닝을 가능하게 해줌
Column Projection Information - 각 Operation 단계에서 어떤 Column을 추출하는지에 대한 정보

추가 가능한 세부 옵션들 :
- ROWS
- BYTES
- COST
- PARTITION
- PARALLEL(TQ, IN-OUT, PQ Distrib 정보)
- PREDICATE
- PROJECTION
- ALIAS(Query Block Name)
- REMOTE
- NOTE

사용예


SQL>  explain plan for
  2   select count(1) from test_table2 where col1 like '2016%';

해석되었습니다.

SQL> select plan_table_output
  2  from table(dbms_xplan.display);

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------

Plan hash value: 3110898069

----------------------------------------------------------------------------------------
| Id  | Operation             | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |                |     1 |    18 |    17   (0)| 00:00:01 |
|   1 |  SORT AGGREGATE       |                |     1 |    18 |            |          |
|*  2 |   INDEX FAST FULL SCAN| TEST_TABLE2_PK | 10389 |   182K|    17   (0)| 00:00:01 |
----------------------------------------------------------------------------------------

Predicate Information (identified by operation id):

   2 - filter("COL1" LIKE '2016%')

14 개의 행이 선택되었습니다.

SQL> select plan_table_output
  2  from table(dbms_xplan.display('plan_table',null));

결과동일

SQL> select plan_table_output
  2  from table(dbms_xplan.display('plan_table',null,'typical'));

결과 동일

SQL> select plan_table_output
  2  from table(dbms_xplan.display('plan_table',null,'basic rows bytes cost predicate'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 3110898069

-----------------------------------------------------------------------------
| Id  | Operation             | Name           | Rows  | Bytes | Cost (%CPU)|
-----------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |                |     1 |    18 |    17   (0)|
|   1 |  SORT AGGREGATE       |                |     1 |    18 |            |
|*  2 |   INDEX FAST FULL SCAN| TEST_TABLE2_PK | 10389 |   182K|    17   (0)|
-----------------------------------------------------------------------------

Predicate Information (identified by operation id):

   2 - filter("COL1" LIKE '2016%')

14 개의 행이 선택되었습니다.

SQL>  select plan_table_output
  2     from table(dbms_xplan.display('plan_table',null,'advanced'));

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------

Plan hash value: 3110898069

----------------------------------------------------------------------------------------
| Id  | Operation             | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT      |                |     1 |    18 |    17   (0)| 00:00:01 |
|   1 |  SORT AGGREGATE       |                |     1 |    18 |            |          |
|*  2 |   INDEX FAST FULL SCAN| TEST_TABLE2_PK | 10389 |   182K|    17   (0)| 00:00:01 |
----------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):

   1 - SEL$1
   2 - SEL$1 / TEST_TABLE2@SEL$1

Outline Data
-------------

  /*+
      BEGIN_OUTLINE_DATA
      INDEX_FFS(@"SEL$1" "TEST_TABLE2"@"SEL$1" ("TEST_TABLE2"."COL1"
              "TEST_TABLE2"."COL2"))
      OUTLINE_LEAF(@"SEL$1")
      ALL_ROWS
      DB_VERSION('11.2.0.3')
      OPTIMIZER_FEATURES_ENABLE('11.2.0.3')
      IGNORE_OPTIM_EMBEDDED_HINTS
      END_OUTLINE_DATA
  */

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - filter("COL1" LIKE '2016%')

Column Projection Information (identified by operation id):
-----------------------------------------------------------

   1 - (#keys=0) COUNT(*)[22]

40 개의 행이 선택되었습니다.

filter_preds


filter_preds - plan_table에서 출력되어야할 row를 지정할 수 있다.

SQL> select plan_id from plan_table where statement_id = 'query';

   PLAN_ID
----------
      2836
      2836
      2836
      3341
      3341
      3341

6 개의 행이 선택되었습니다.

SQL> select plan_table_output
  2    from table(dbms_xplan.display(null,'query','BASIC','plan_id = 2836'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 2346248975

------------------------------------------
| Id  | Operation          | Name        |
------------------------------------------
|   0 | UPDATE STATEMENT   |             |
|   1 |  UPDATE            | MMORDRCT    |
|   2 |   INDEX UNIQUE SCAN| MMORDRCT_PK |
------------------------------------------

9 개의 행이 선택되었습니다.

SQL>  select plan_table_output
  2     from table(dbms_xplan.display(null,'query','BASIC','plan_id = 3341'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 647164865

--------------------------------------------
| Id  | Operation         | Name           |
--------------------------------------------
|   0 | SELECT STATEMENT  |                |
|   1 |  SORT AGGREGATE   |                |
|   2 |   INDEX RANGE SCAN| MMMEDORT_IDX15 |
--------------------------------------------

9 개의 행이 선택되었습니다.

SQL> select plan_table_output
  2      from table(dbms_xplan.display(null,'query ','BASIC','depth < 2'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------
Plan hash value: 647164865

---------------------------------
| Id  | Operation        | Name |
---------------------------------
|   0 | SELECT STATEMENT |      |
|   1 |  SORT AGGREGATE  |      |
---------------------------------

8 개의 행이 선택되었습니다.

(2)캐싱된 커서의 실제 실행계획 출력

커서 : 하드파싱 과정을 거쳐 메모리에 적재된 SQL과 Parse Tree, 실행계획, 그리고 그것을 실행하는데 필요한 정보를 담은 SQL Area
오라클은 라이브러리 캐시에 캐싱돼 있는 각 커서에 대한 수행통계를 볼 수 있도록 v$sql, v$sql_plan, v$sql_plan_statistics, v$sql_plan_statistics_all 뷰를 제공
v$sql_plan 뷰를 통해 원하는 형식으로 포맷팅할 수 있지만 다음 패키지를 사용하면 편하게 포맷팅된 실행계획을 볼 수 있다.

정의


DBMS_XPLAN.DISPLAY_CURSOR(sql_id        IN  VARCHAR2  DEFAULT  NULL,--생략시 최근 sql_id
                          child_number  IN  NUMBER    DEFAULT  NULL,--생략시 최근 sql_id의 child_number 
                          format        IN  VARCHAR2  DEFAULT  'TYPICAL');

Format 옵션

dbms_xplan.display 함수에 사용했던 포맷을 그대로 사용할 수 있으며 다음 세부 format 옵션이 추가된다.

옵션	설명
IOSTATS	IO관련 분석정보를 보여준다
MEMSTATS	메모리관련 분석정보를 보여준다(해시조인,소트,비트맵오퍼레이션등)
ALLSTATS	IOSTATS + MEMSTATS
LAST	마지막으로 수행된 분석정보만 보여준다

사용예


SQL> select count(1)
  2  from test_table1
  3  where exists(select 1 from test_table2 where col1 = test_table1.col1);

  COUNT(1)
----------
       294

SQL> select * from table(dbms_xplan.display_cursor);

PLAN_TABLE_OUTPUT
-------------------------------------------------------------------------------------------

SQL_ID  a8fs5xmvhz2hb, child number 0
-------------------------------------
select count(1)  from test_table1  where exists(select 1 from
test_table2 where col1 = test_table1.col1)

Plan hash value: 4055452834

------------------------------------------------------------------------------------------
| Id  | Operation               | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT        |                |       |       |    19 (100)|          |
|   1 |  SORT AGGREGATE         |                |     1 |    36 |            |          |
|   2 |   NESTED LOOPS          |                |   302 | 10872 |    19  (11)| 00:00:01 |
|   3 |    SORT UNIQUE          |                | 11985 |   210K|    17   (0)| 00:00:01 |
|   4 |     INDEX FAST FULL SCAN| TEST_TABLE2_PK | 11985 |   210K|    17   (0)| 00:00:01 |
|*  5 |    INDEX UNIQUE SCAN    | TEST_TABLE1_PK |     1 |    18 |     0   (0)|          |
------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("COL1"="TEST_TABLE1"."COL1")

23 개의 행이 선택되었습니다.

SQL> select count(1)
  2  from test_table1
  3  where exists(select 1 from test_table2 where col1 = test_table1.col1);

  COUNT(1)
----------
       294

SQL> column prev_sql_id new_value sql_id
SQL> column prev_child_number new_value child_no
SQL> select prev_sql_id, prev_child_number
  2  from v$session
  3  where sid=userenv('sid')
  4  and username is not null
  5  and prev_hash_value <> 0;

PREV_SQL_ID                PREV_CHILD_NUMBER
-------------------------- -----------------
avmgkkjah7pbm                              0

SQL> select * from table(dbms_xplan.display_cursor('avmgkkjah7pbm',0,'iostats'));

PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------

SQL_ID  avmgkkjah7pbm, child number 0
-------------------------------------
select count(1)  from test_table1  where exists(select 1 from
test_table2 where col1 = test_table1.col1)

Plan hash value: 4055452834

-----------------------------------------------------------
| Id  | Operation               | Name           | E-Rows |
-----------------------------------------------------------
|   0 | SELECT STATEMENT        |                |        |
|   1 |  SORT AGGREGATE         |                |      1 |
|   2 |   NESTED LOOPS          |                |    302 |
|   3 |    SORT UNIQUE          |                |  11985 |
|   4 |     INDEX FAST FULL SCAN| TEST_TABLE2_PK |  11985 |
|*  5 |    INDEX UNIQUE SCAN    | TEST_TABLE1_PK |      1 |
-----------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("COL1"="TEST_TABLE1"."COL1")

Note
-----
   - Warning: basic plan statistics not available. These are only collected when:
       * hint 'gather_plan_statistics' is used for the statement or
       * parameter 'statistics_level' is set to 'ALL', at session or system level


29 개의 행이 선택되었습니다.

SQL> select * from table(dbms_xplan.display_cursor('avmgkkjah7pbm',0,'memstats'));

PLAN_TABLE_OUTPUT
--------------------------------------------------------------------------------------

SQL_ID  avmgkkjah7pbm, child number 0
-------------------------------------
select count(1)  from test_table1  where exists(select 1 from
test_table2 where col1 = test_table1.col1)

Plan hash value: 4055452834

--------------------------------------------------------------------------------------
| Id  | Operation               | Name           | E-Rows |  OMem |  1Mem |  O/1/M   |
--------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT        |                |        |       |       |          |
|   1 |  SORT AGGREGATE         |                |      1 |       |       |          |
|   2 |   NESTED LOOPS          |                |    302 |       |       |          |
|   3 |    SORT UNIQUE          |                |  11985 | 22528 | 22528 |     1/0/0|
|   4 |     INDEX FAST FULL SCAN| TEST_TABLE2_PK |  11985 |       |       |          |
|*  5 |    INDEX UNIQUE SCAN    | TEST_TABLE1_PK |      1 |       |       |          |
--------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("COL1"="TEST_TABLE1"."COL1")

Note
-----
   - Warning: basic plan statistics not available. These are only collected when:
       * hint 'gather_plan_statistics' is used for the statement or
       * parameter 'statistics_level' is set to 'ALL', at session or system level


29 개의 행이 선택되었습니다.

SQL> select * from table(dbms_xplan.display_cursor('avmgkkjah7pbm',0,'advanced allstats last'));

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------------------------

SQL_ID  avmgkkjah7pbm, child number 0
-------------------------------------
select count(1)  from test_table1  where exists(select 1 from
test_table2 where col1 = test_table1.col1)

Plan hash value: 4055452834

----------------------------------------------------------------------------------------------------------------------
| Id  | Operation               | Name           | E-Rows |E-Bytes| Cost (%CPU)| E-Time   |  OMem |  1Mem | Used-Mem |
----------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT        |                |        |       |    19 (100)|          |       |    |             |
|   1 |  SORT AGGREGATE         |                |      1 |    36 |            |          |       |    |             |
|   2 |   NESTED LOOPS          |                |    302 | 10872 |    19  (11)| 00:00:01 |       |    |             |
|   3 |    SORT UNIQUE          |                |  11985 |   210K|    17   (0)| 00:00:01 | 22528 | 22528 |20480  (0)|
|   4 |     INDEX FAST FULL SCAN| TEST_TABLE2_PK |  11985 |   210K|    17   (0)| 00:00:01 |       |    |             |
|*  5 |    INDEX UNIQUE SCAN    | TEST_TABLE1_PK |      1 |    18 |     0   (0)|          |       |    |             |
----------------------------------------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------

   1 - SEL$5DA710D3
   4 - SEL$5DA710D3 / TEST_TABLE2@SEL$2
   5 - SEL$5DA710D3 / TEST_TABLE1@SEL$1

Outline Data
-------------

  /*+
      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('11.2.0.3')
      DB_VERSION('11.2.0.3')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$5DA710D3")
      UNNEST(@"SEL$2")
      OUTLINE(@"SEL$1")
      OUTLINE(@"SEL$2")
      INDEX_FFS(@"SEL$5DA710D3" "TEST_TABLE2"@"SEL$2" ("TEST_TABLE2"."COL1" "TEST_TABLE2"."COL2"))
      INDEX(@"SEL$5DA710D3" "TEST_TABLE1"@"SEL$1" ("TEST_TABLE1"."COL1"))
      LEADING(@"SEL$5DA710D3" "TEST_TABLE2"@"SEL$2" "TEST_TABLE1"@"SEL$1")
      USE_NL(@"SEL$5DA710D3" "TEST_TABLE1"@"SEL$1")
      END_OUTLINE_DATA
  */

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("COL1"="TEST_TABLE1"."COL1")

Column Projection Information (identified by operation id):
-----------------------------------------------------------

   1 - (#keys=0) COUNT(*)[22]
   3 - (#keys=1) "COL1"[VARCHAR2,18]
   4 - "COL1"[VARCHAR2,18]

Note
-----
   - Warning: basic plan statistics not available. These are only collected when:
       * hint 'gather_plan_statistics' is used for the statement or
       * parameter 'statistics_level' is set to 'ALL', at session or system level


63 개의 행이 선택되었습니다.

(3)캐싱된 커서의 Row Source별 수행 통계 출력

Row Source별 수행 통계 수집
- gather_plan_statistics 힌트 사용
- 시스템 또는 세션 레벨에서 statistics_level 파라미터를 all로 설정 - ALTER SESSION SET STATISTICS_LEVEL = ALL;
- _rowsource_execution_statistics 파라미터를 true로 설정 - ALTER SESSION SET "_ROWSOURCE_EXECUTION_STATISTICS" = TRUE;
- SQL Trace 걸기

해당 통계는 v$sql_plan_statistics 또는 v$sql_plan_statistics_all 뷰를 이용하면 된다.

사용예



SQL> select /*+gather_plan_statistics*/ count(1)
  2  from test_table1
  3  where exists(select 1 from test_table2 where col1 = test_table1.col1);

  COUNT(1)
----------
       294

SQL> select * from table(dbms_xplan.display_cursor(null,null,'advanced allstats last'));

PLAN_TABLE_OUTPUT
---------------------------------------------------------------------------------------------------------------------------------------------------------------

SQL_ID  0zf6jkp8n4fjv, child number 0
-------------------------------------
select /*+gather_plan_statistics*/ count(1) from test_table1
where exists(select 1 from test_table2 where col1 =
test_table1.col1)

Plan hash value: 4055452834

---------------------------------------------------------------------------------------------------------------------------------------------------------------
| Id  | Operation               | Name           | Starts | E-Rows |E-Bytes| Cost (%CPU)| E-Time   | A-Rows |   A-Time   | Buffers |  OMem |  1Mem | Used-Mem |
---------------------------------------------------------------------------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT        |                |      1 |        |       |    19 (100)|          |      1 |00:00:00.01 |     161 |       |       |          |
|   1 |  SORT AGGREGATE         |                |      1 |      1 |    36 |            |          |      1 |00:00:00.01 |     161 |       |       |          |
|   2 |   NESTED LOOPS          |                |      1 |    302 | 10872 |    19  (11)| 00:00:01 |    294 |00:00:00.01 |     161 |       |       |          |
|   3 |    SORT UNIQUE          |                |      1 |  11985 |   210K|    17   (0)| 00:00:01 |    302 |00:00:00.01 |      64 |  2528 | 22528 |20480  (0)|
|   4 |     INDEX FAST FULL SCAN| TEST_TABLE2_PK |      1 |  11985 |   210K|    17   (0)| 00:00:01 |  11985 |00:00:00.01 |      64 |       |       |          |
|*  5 |    INDEX UNIQUE SCAN    | TEST_TABLE1_PK |    302 |      1 |    18 |     0   (0)|          |    294 |00:00:00.01 |      97 |       |       |          |
---------------------------------------------------------------------------------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------

   1 - SEL$5DA710D3
   4 - SEL$5DA710D3 / TEST_TABLE2@SEL$2
   5 - SEL$5DA710D3 / TEST_TABLE1@SEL$1

Outline Data
-------------

  /*+
      BEGIN_OUTLINE_DATA
      IGNORE_OPTIM_EMBEDDED_HINTS
      OPTIMIZER_FEATURES_ENABLE('11.2.0.3')
      DB_VERSION('11.2.0.3')
      ALL_ROWS
      OUTLINE_LEAF(@"SEL$5DA710D3")
      UNNEST(@"SEL$2")
      OUTLINE(@"SEL$1")
      OUTLINE(@"SEL$2")
      INDEX_FFS(@"SEL$5DA710D3" "TEST_TABLE2"@"SEL$2" ("TEST_TABLE2"."COL1" "TEST_TABLE2"."COL2"))
      INDEX(@"SEL$5DA710D3" "TEST_TABLE1"@"SEL$1" ("TEST_TABLE1"."COL1"))
      LEADING(@"SEL$5DA710D3" "TEST_TABLE2"@"SEL$2" "TEST_TABLE1"@"SEL$1")
      USE_NL(@"SEL$5DA710D3" "TEST_TABLE1"@"SEL$1")
      END_OUTLINE_DATA
  */

Predicate Information (identified by operation id):
---------------------------------------------------

   5 - access("COL1"="TEST_TABLE1"."COL1")

Column Projection Information (identified by operation id):
-----------------------------------------------------------

   1 - (#keys=0) COUNT(*)[22]
   3 - (#keys=1) "COL1"[VARCHAR2,18]
   4 - "COL1"[VARCHAR2,18]


58 개의 행이 선택되었습니다.

Row Source 분석 항목

항목	설명
Id	Operation ID
Operation	로우 단위의 액세스 정보
Name	액세스하는 오브젝트의 정보
Starts	각 Operation을 수행한 횟수
E-Rows	예측 Row수
E-Bytes	예측 byte
Cost (%CPU)	Cost
E-Time	예측 수행시간
A-Rows	실측 Row수
A-Time	실측 수행시간
Buffers	실측 Logical Block
OMem	Optimal Execution에 필요한 메모리(예측) - 메모리에서만 작업 가능한 메모리 크기
1Mem	One-Pass Execution에 필요한 메모리(예측) - 디스크를 1회라도 했을 때 필요한 메모리 크기
Used-Mem	마지막 실행시 사용한 메모리

Query Block Name 활용

Query Block Name 을 지정하여 실행계획 수정에 사용할 수 있다.


억지이긴 하지만 테스트해본다.
SQL> select /*+no_unnest(@sonexists)*/ count(1)  from test_table1 a
  2  where exists(select /*+ qb_name(sonexists) */ 1 from test_table2 b
  3  where col1 = a.col1);

  COUNT(1)
----------
       294

SQL> select * from table(dbms_xplan.display_cursor(null,0,'all last'));

PLAN_TABLE_OUTPUT
-----------------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------
SQL_ID  8fuyum6qfw3h8, child number 0
-------------------------------------
select /*+no_unnest(@sonexists)*/ count(1)  from test_table1 a
where exists(select /*+ qb_name(sonexists) */ 1 from test_table2
b where col1 = a.col1)

Plan hash value: 767868621

-----------------------------------------------------------------------------------------
| Id  | Operation              | Name           | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT       |                |       |       | 76648 (100)|          |
|   1 |  SORT AGGREGATE        |                |     1 |    18 |            |          |
|*  2 |   FILTER               |                |       |       |            |          |
|   3 |    INDEX FAST FULL SCAN| TEST_TABLE1_PK | 41722 |   733K|    57   (2)| 00:00:01 |
|*  4 |    INDEX RANGE SCAN    | TEST_TABLE2_PK |     2 |    36 |     2   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------

Query Block Name / Object Alias (identified by operation id):
-------------------------------------------------------------

   1 - SEL$1
   3 - SEL$1     / A@SEL$1
   4 - SONEXISTS / B@SONEXISTS

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - filter( IS NOT NULL)
   4 - access("COL1"=:B1)

Column Projection Information (identified by operation id):
-----------------------------------------------------------

   1 - (#keys=0) COUNT(*)[22]
   3 - "A"."COL1"[VARCHAR2,18]
   4 - "COL1"[VARCHAR2,18]


38 개의 행이 선택되었습니다.

DBMS_XPLAN 패키지 (by hrson81) [2017.01.03]

04.DBMS_XPLAN 패키지

(1)예상 실행계획 출력

(2)캐싱된 커서의 실제 실행계획 출력

(3)캐싱된 커서의 Row Source별 수행 통계 출력