sql - 如何在嵌套查询的最外层查询中使用 noindex 提示？

Question

我有一个查询结构，其中有 3 个嵌套查询（例如 select * from (select * from (select * from table ) a ) b

试图避免有一个索引，因为它会导致运行时间过长。它在计划中出现了两次。我在最里面的查询上使用了 noindex 提示来删除它的一个实例，但我似乎无法摆脱第二个实例。

有没有办法在嵌套查询的外部查询上使用 noindex？

编辑：更详细的查询示例。请注意，在实际查询中，每个级别都有 GROUP BY 语句，但 WHERE 语句仅在最里面的查询中。

Select /*+ parallel(8) no_index(b,bad_index)  */
 b.col1
 b.col2
 b.col3 
FROM
  (Select /*+ parallel(8) no_index(a,bad_index)  */
    a.col1
    a.col2
    a.col3
  FROM 
(SELECT  /*+ parallel(8) no_index(t,bad_index)  */
       t.col1
       t.col2
       t.col3
    
    FROM table_1 t
    INNER JOIN table_2 t2
          ON t.col1=t2.col1
    WHERE
        t.col2='value' ) a
) b

计划如下。请注意，这是我为了匿名而更改了表名的实际执行计划。为了简单起见，我没有在示例中包含一些连接。第 72/73 行包含我试图避免的索引。我添加了谓词信息。

   | Id   | Operation                                                                       | Name                      | Rows      | Bytes       | Cost    | Time     |
---------------------------------------------------------------------------------------------------------------------------------------------------------------------
|    0 | SELECT STATEMENT                                                                |                           |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    1 |   PX COORDINATOR                                                                |                           |           |             |         |          |
|    2 |    PX SEND QC (RANDOM)                                                          | :TQ10014                  |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    3 |     SORT GROUP BY                                                               |                           |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    4 |      PX RECEIVE                                                                 |                           |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    5 |       PX SEND HASH                                                              | :TQ10013                  |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    6 |        SORT GROUP BY                                                            |                           |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    7 |         PX RECEIVE                                                              |                           |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    8 |          PX SEND HASH                                                           | :TQ10012                  |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|    9 |           SORT GROUP BY                                                         |                           |  84613730 | 20138067740 | 5534656 | 00:03:37 |
|   10 |            VIEW                                                                 |                           |  84613730 | 20138067740 | 5135062 | 00:03:21 |
|   11 |             WINDOW SORT                                                         |                           |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   12 |              PX RECEIVE                                                         |                           |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   13 |               PX SEND HASH                                                      | :TQ10011                  |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   14 |                WINDOW BUFFER                                                    |                           |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   15 |                 SORT GROUP BY                                                   |                           |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   16 |                  PX RECEIVE                                                     |                           |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   17 |                   PX SEND HASH                                                  | :TQ10010                  |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   18 |                    HASH GROUP BY                                                |                           |  84613730 | 22338024720 | 5135062 | 00:03:21 |
|   19 |                     VIEW                                                        |                           |  84613730 | 22338024720 | 4201665 | 00:02:45 |
|   20 |                      WINDOW SORT                                                |                           |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   21 |                       PX RECEIVE                                                |                           |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   22 |                        PX SEND HASH                                             | :TQ10009                  |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   23 |                         WINDOW BUFFER                                           |                           |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   24 |                          SORT GROUP BY                                          |                           |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   25 |                           PX RECEIVE                                            |                           |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   26 |                            PX SEND HASH                                         | :TQ10008                  |  84613730 | 33760878270 | 4201665 | 00:02:45 |
|   27 |                             HASH GROUP BY                                       |                           |  84613730 | 33760878270 | 4201665 | 00:02:45 |
| * 28 |                              HASH JOIN                                          |                           |  84613730 | 33760878270 | 2809746 | 00:01:50 |
|   29 |                               PX RECEIVE                                        |                           |     48812 |     1366736 |       2 | 00:00:01 |
|   30 |                                PX SEND BROADCAST                                | :TQ10003                  |     48812 |     1366736 |       2 | 00:00:01 |
|   31 |                                 PX BLOCK ITERATOR                               |                           |     48812 |     1366736 |       2 | 00:00:01 |
|   32 |                                  TABLE ACCESS STORAGE FULL                      | Table5       |     48812 |     1366736 |       2 | 00:00:01 |
| * 33 |                               HASH JOIN RIGHT OUTER                             |                           |  84350244 | 31293940524 | 2809707 | 00:01:50 |
|   34 |                                PX RECEIVE                                       |                           |     48812 |     1025052 |       2 | 00:00:01 |
|   35 |                                 PX SEND BROADCAST                               | :TQ10004                  |     48812 |     1025052 |       2 | 00:00:01 |
|   36 |                                  PX BLOCK ITERATOR                              |                           |     48812 |     1025052 |       2 | 00:00:01 |
|   37 |                                   TABLE ACCESS STORAGE FULL                     | Table5       |     48812 |     1025052 |       2 | 00:00:01 |
| * 38 |                                HASH JOIN RIGHT OUTER                            |                           |  84087578 | 29430652300 | 2809669 | 00:01:50 |
|   39 |                                 PX RECEIVE                                      |                           |     37177 |      669186 |       3 | 00:00:01 |
|   40 |                                  PX SEND BROADCAST                              | :TQ10005                  |     37177 |      669186 |       3 | 00:00:01 |
|   41 |                                   PX BLOCK ITERATOR                             |                           |     37177 |      669186 |       3 | 00:00:01 |
|   42 |                                    TABLE ACCESS STORAGE FULL                    | Table4              |     37177 |      669186 |       3 | 00:00:01 |
| * 43 |                                 HASH JOIN                                       |                           |  84087578 | 27917075896 | 2809629 | 00:01:50 |
|   44 |                                  TABLE ACCESS STORAGE FULL                      | Table4                |     37177 |      669186 |       3 | 00:00:01 |
| * 45 |                                  HASH JOIN OUTER                                |                           |  84087578 | 26403499492 | 2809590 | 00:01:50 |
|   46 |                                   JOIN FILTER CREATE                            | :BF0000                   |  84087578 | 17490216224 | 2134146 | 00:01:24 |
|   47 |                                    PX RECEIVE                                   |                           |  84087578 | 17490216224 | 2134146 | 00:01:24 |
|   48 |                                     PX SEND HASH (NULL RANDOM)                  | :TQ10006                  |  84087578 | 17490216224 | 2134146 | 00:01:24 |
| * 49 |                                      HASH JOIN BUFFERED                         |                           |  84087578 | 17490216224 | 2134146 | 00:01:24 |
|   50 |                                       PART JOIN FILTER CREATE                   | :BF0001                   | 345508495 | 11401780335 |  589579 | 00:00:24 |
|   51 |                                        PX RECEIVE                               |                           | 345508495 | 11401780335 |  589579 | 00:00:24 |
|   52 |                                         PX SEND HASH                            | :TQ10000                  | 345508495 | 11401780335 |  589579 | 00:00:24 |
|   53 |                                          PX PARTITION LIST INLIST               |                           | 345508495 | 11401780335 |  589579 | 00:00:24 |
| * 54 |                                           TABLE ACCESS STORAGE FULL             | Table3 | 345508495 | 11401780335 |  589579 | 00:00:24 |
| * 55 |                                       HASH JOIN                                 |                           |  84087578 | 14715326150 | 1532914 | 00:01:00 |
|   56 |                                        JOIN FILTER CREATE                       | :BF0003                   |  84087578 | 12276786388 | 1201043 | 00:00:47 |
|   57 |                                         PART JOIN FILTER CREATE                 | :BF0002                   |  84087578 | 12276786388 | 1201043 | 00:00:47 |
|   58 |                                          PX RECEIVE                             |                           |  84087578 | 12276786388 | 1201043 | 00:00:47 |
|   59 |                                           PX SEND HASH                          | :TQ10001                  |  84087578 | 12276786388 | 1201043 | 00:00:47 |
|   60 |                                            PX PARTITION LIST INLIST             |                           |  84087578 | 12276786388 | 1201043 | 00:00:47 |
| * 61 |                                             TABLE ACCESS STORAGE FULL           | Table1      |  84087578 | 12276786388 | 1201043 | 00:00:47 |
|   62 |                                        PX RECEIVE                               |                           | 388151817 | 11256402693 |  320877 | 00:00:13 |
|   63 |                                         PX SEND HASH                            | :TQ10002                  | 388151817 | 11256402693 |  320877 | 00:00:13 |
|   64 |                                          JOIN FILTER USE                        | :BF0003                   | 388151817 | 11256402693 |  320877 | 00:00:13 |
|   65 |                                           PX PARTITION LIST INLIST              |                           | 388151817 | 11256402693 |  320877 | 00:00:13 |
| * 66 |                                            TABLE ACCESS STORAGE FULL            |Table2           | 388151817 | 11256402693 |  320877 | 00:00:13 |
|   67 |                                   PX RECEIVE                                    |                           | 191371730 | 20285403380 |  660306 | 00:00:26 |
|   68 |                                    PX SEND HASH                                 | :TQ10007                  | 191371730 | 20285403380 |  660306 | 00:00:26 |
|   69 |                                     JOIN FILTER USE                             | :BF0000                   | 191371730 | 20285403380 |  660306 | 00:00:26 |
|   70 |                                      PX PARTITION LIST INLIST                   |                           | 191371730 | 20285403380 |  660306 | 00:00:26 |
| * 71 |                                       TABLE ACCESS BY LOCAL INDEX ROWID BATCHED | Table1      | 191371730 | 20285403380 |  660306 | 00:00:26 |
|   72 |                                        BITMAP CONVERSION TO ROWIDS              |                           |           |             |         |          |
| * 73 |                                         BITMAP INDEX RANGE SCAN                 | BAD_INDEX     |           |             |         |          |



   * 73 - access("B"."date_field"(+)>=TO_NUMBER(TO_CHAR(LAST_DAY(SYSDATE@!-INTERVAL'+00-06' YEAR(2) TO MONTH),'YYYYMMDD')))
* 73 - filter(NVL("B"."date_field"(+),99990101)>=TO_NUMBER(TO_CHAR(LAST_DAY(SYSDATE@!-INTERVAL'+00-06' YEAR(2) TO MONTH),'YYYYMMDD')) AND
  "B"."date_field"(+)>=TO_NUMBER(TO_CHAR(LAST_DAY(SYSDATE@!-INTERVAL'+00-06' YEAR(2) TO MONTH),'YYYYMMDD')))

Answer 1

首先，您需要查看提示的扩展语法no_index：

no_index( [queryblock] tablespec [indexspec])

tablespec在 哪里

例如对于这个查询：

Select
 b.col1,
 b.col2,
 b.col3 
FROM
  (Select
    a.col1,
    a.col2,
    a.col3
  FROM 
   (SELECT
       t.col1,
       t.col2,
       t.col3
    FROM table_1 t
    JOIN table_2 t2
         on t.col1 = t2.col1
    WHERE
        t2.col2=:bind
   ) a
) b;

您可以使用no_index(b.a.t2)，即外部内联视图 b，然后是内部内联视图 a，最后是您的表别名。但是（！）不要忘记官方说明：

注意：使用 tablespec 子句指定全局提示不适用于使用ANSI连接的查询，因为优化器在解析期间会生成额外的视图。相反，指定 @queryblock 以指示应用提示的查询块。

所以对于 ANSI 连接（使用 查询join），最好使用@queryblock. 并且更容易使用解释计划附加部分，如alias, projection, note, report_hint. 您可以使用 轻松完成format=>'all'，但我也建议使用+outline和+hint_report，例如：

select * from table(dbms_xplan.display(format=>'all +outline +hint_report'));

从文档：

format 控制计划的详细程度。它接受以下值：

• BASIC：显示计划中的最少信息——操作 ID、操作名称及其选项。
• 典型：这是默认设置。显示计划中最相关的信息（操作 ID、名称和选项、#rows、#bytes 和优化器成本）。修剪、并行和谓词信息仅在适用时显示。仅排除 PROJECTION、ALIAS 和 REMOTE SQL 信息（见下文）。
• SERIAL：与 TYPICAL 类似，只是不显示并行信息，即使计划并行执行。
• ALL：最大用户级别。包括以 TYPICAL 级别显示的信息以及附加信息（如果操作是分布式的，则 PROJECTION、ALIAS 和有关 REMOTE SQL 的信息）。

事实上，“ALL”并不是“最高级别”。还有更详细advanced的格式 - ，但它没有正式记录（虽然你可以在 MOS 上找到它），所以我不建议这样做。

例如，我们有这些表和索引：

create table table_1(col1 primary key,col2,col3)
  as select 
        level,
        trunc(level/10) as col2,
        rpad('x',100) as col3
     from dual
     connect by level<=10000;
create table table_2(col1,col2,col3)
  as select 
        level,
        trunc(level/10) as col2,
        rpad('x',100) as col3
     from dual
     connect by level<=10000;
create index BAD_INDEX on table_2(col2,col1);

让我们得到这个查询的执行计划：

explain plan for
Select
 b.col1,
 b.col2,
 b.col3 
FROM
  (Select
    a.col1,
    a.col2,
    a.col3
  FROM 
   (SELECT
       t.col1,
       t.col2,
       t.col3
    FROM table_1 t
    JOIN table_2 t2
         on t.col1 = t2.col1
    WHERE
        t2.col2=:bind
   ) a
) b;
select * from table(dbms_xplan.display('','','all +outline +hint_report'));

执行计划：

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Plan hash value: 2962753836

---------------------------------------------------------------------------------------------
| Id  | Operation                    | Name         | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |              |    10 |  1170 |    12   (0)| 00:00:01 |
|   1 |  NESTED LOOPS                |              |    10 |  1170 |    12   (0)| 00:00:01 |
|   2 |   NESTED LOOPS               |              |    10 |  1170 |    12   (0)| 00:00:01 |
|*  3 |    INDEX RANGE SCAN          | BAD_INDEX    |    10 |    80 |     2   (0)| 00:00:01 |
|*  4 |    INDEX UNIQUE SCAN         | SYS_C0010147 |     1 |       |     0   (0)| 00:00:01 |
|   5 |   TABLE ACCESS BY INDEX ROWID| TABLE_1      |     1 |   109 |     1   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------

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

   1 - SEL$535BA485
   3 - SEL$535BA485 / T2@SEL$3
   4 - SEL$535BA485 / T@SEL$3
   5 - SEL$535BA485 / T@SEL$3

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

  /*+
      BEGIN_OUTLINE_DATA
      NLJ_BATCHING(@"SEL$535BA485" "T"@"SEL$3")
      USE_NL(@"SEL$535BA485" "T"@"SEL$3")
      LEADING(@"SEL$535BA485" "T2"@"SEL$3" "T"@"SEL$3")
      INDEX(@"SEL$535BA485" "T"@"SEL$3" ("TABLE_1"."COL1"))
      INDEX(@"SEL$535BA485" "T2"@"SEL$3" ("TABLE_2"."COL2" "TABLE_2"."COL1"))
      OUTLINE(@"SEL$3")
      OUTLINE(@"SEL$4")
      MERGE(@"SEL$3" >"SEL$4")
      OUTLINE(@"SEL$37633EB5")
      OUTLINE(@"SEL$2")
      MERGE(@"SEL$37633EB5" >"SEL$2")
      OUTLINE(@"SEL$BB1798A6")
      OUTLINE(@"SEL$1")
      MERGE(@"SEL$BB1798A6" >"SEL$1")
      OUTLINE_LEAF(@"SEL$535BA485")
      ALL_ROWS
      DB_VERSION('19.1.0')
      OPTIMIZER_FEATURES_ENABLE('19.1.0')
      IGNORE_OPTIM_EMBEDDED_HINTS
      END_OUTLINE_DATA
  */

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

   3 - access("T2"."COL2"=TO_NUMBER(:BIND))
   4 - access("T"."COL1"="T2"."COL1")

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

   1 - (#keys=0) "T"."COL1"[NUMBER,22], "T"."COL2"[NUMBER,22],
       "T"."COL3"[VARCHAR2,100]
   2 - (#keys=0) "T".ROWID[ROWID,10], "T"."COL1"[NUMBER,22]
   3 - "T2"."COL1"[NUMBER,22]
   4 - "T".ROWID[ROWID,10], "T"."COL1"[NUMBER,22]
   5 - "T"."COL2"[NUMBER,22], "T"."COL3"[VARCHAR2,100]

如您所见，我们在这里有两个索引访问的嵌套循环：第 3 行 - BAD_INDEX 的 IRS（索引范围扫描）和第 4 行 IUS（索引唯一扫描）。在本OUTLINE节中，我们看到了 4 个最有趣的提示：

      USE_NL(@"SEL$535BA485" "T"@"SEL$3")
      LEADING(@"SEL$535BA485" "T2"@"SEL$3" "T"@"SEL$3")
      INDEX(@"SEL$535BA485" "T"@"SEL$3" ("TABLE_1"."COL1"))
      INDEX(@"SEL$535BA485" "T2"@"SEL$3" ("TABLE_2"."COL2" "TABLE_2"."COL1"))

因此，例如，如果我们想禁用对 T2 的索引访问，我们可以查看大纲提示 INDEX(@"SEL$535BA485" "T2"@"SEL$3" ("TABLE_2"."COL2" "TABLE_2"."COL1")) ，从中获取查询块（简称 QBName） -@"SEL$535BA485"和表别名 -"T2"@"SEL$3"并在我们的提示中添加使用它们作为NO_INDEX(@"SEL$535BA485" "T2"@"SEL$3" BAD_INDEX)

示例 #2：

explain plan for
Select--+ NO_INDEX(@"SEL$535BA485" "T2"@"SEL$3")
 b.col1,
 b.col2,
 b.col3 
FROM
  (Select
    a.col1,
    a.col2,
    a.col3
  FROM 
   (SELECT
       t.col1,
       t.col2,
       t.col3
    FROM table_1 t
    JOIN table_2 t2
         on t.col1 = t2.col1
    WHERE
        t2.col2=:bind
   ) a
) b;
select * from table(dbms_xplan.display('','','all +outline +hint_report'));

执行计划#2：

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Plan hash value: 247834218

---------------------------------------------------------------------------------------------
| Id  | Operation                    | Name         | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |              |    10 |  1170 |    58   (0)| 00:00:01 |
|   1 |  NESTED LOOPS                |              |    10 |  1170 |    58   (0)| 00:00:01 |
|   2 |   NESTED LOOPS               |              |    10 |  1170 |    58   (0)| 00:00:01 |
|*  3 |    TABLE ACCESS FULL         | TABLE_2      |    10 |    80 |    48   (0)| 00:00:01 |
|*  4 |    INDEX UNIQUE SCAN         | SYS_C0010147 |     1 |       |     0   (0)| 00:00:01 |
|   5 |   TABLE ACCESS BY INDEX ROWID| TABLE_1      |     1 |   109 |     1   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------

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

   1 - SEL$535BA485
   3 - SEL$535BA485 / T2@SEL$3
   4 - SEL$535BA485 / T@SEL$3
   5 - SEL$535BA485 / T@SEL$3

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

  /*+
      BEGIN_OUTLINE_DATA
      NLJ_BATCHING(@"SEL$535BA485" "T"@"SEL$3")
      USE_NL(@"SEL$535BA485" "T"@"SEL$3")
      LEADING(@"SEL$535BA485" "T2"@"SEL$3" "T"@"SEL$3")
      INDEX(@"SEL$535BA485" "T"@"SEL$3" ("TABLE_1"."COL1"))
      FULL(@"SEL$535BA485" "T2"@"SEL$3")
      OUTLINE(@"SEL$3")
      OUTLINE(@"SEL$4")
      MERGE(@"SEL$3" >"SEL$4")
      OUTLINE(@"SEL$37633EB5")
      OUTLINE(@"SEL$2")
      MERGE(@"SEL$37633EB5" >"SEL$2")
      OUTLINE(@"SEL$BB1798A6")
      OUTLINE(@"SEL$1")
      MERGE(@"SEL$BB1798A6" >"SEL$1")
      OUTLINE_LEAF(@"SEL$535BA485")
      ALL_ROWS
      DB_VERSION('19.1.0')
      OPTIMIZER_FEATURES_ENABLE('19.1.0')
      IGNORE_OPTIM_EMBEDDED_HINTS
      END_OUTLINE_DATA
  */

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

   3 - filter("T2"."COL2"=TO_NUMBER(:BIND))
   4 - access("T"."COL1"="T2"."COL1")

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

   1 - (#keys=0) "T"."COL1"[NUMBER,22], "T"."COL2"[NUMBER,22],
       "T"."COL3"[VARCHAR2,100]
   2 - (#keys=0) "T".ROWID[ROWID,10], "T"."COL1"[NUMBER,22]
   3 - "T2"."COL1"[NUMBER,22]
   4 - "T".ROWID[ROWID,10], "T"."COL1"[NUMBER,22]
   5 - "T"."COL2"[NUMBER,22], "T"."COL3"[VARCHAR2,100]

Hint Report (identified by operation id / Query Block Name / Object Alias):
Total hints for statement: 1
---------------------------------------------------------------------------

   3 -  SEL$535BA485 / T2@SEL$3
           -  NO_INDEX(@"SEL$535BA485" "T2"@"SEL$3")

如您所见，IRS 被替换为 FTS（TABLE ACCESS FULL计划中的全表扫描），hint_report部分显示我们的提示已成功使用。

事实上，这个示例查询太简单了，CBO 甚至可以理解no_index(b.a.t2)这里的标准（下面的示例），但不要忘记它可能不适用于我上面提到的更复杂的 ANSI 语法。

explain plan for
Select--+ NO_INDEX(b.a.t2)
 b.col1,
 b.col2,
 b.col3 
FROM
  (Select
    a.col1,
    a.col2,
    a.col3
  FROM 
   (SELECT
       t.col1,
       t.col2,
       t.col3
    FROM table_1 t
    JOIN table_2 t2
         on t.col1 = t2.col1
    WHERE
        t2.col2=:bind
   ) a
) b;
select * from table(dbms_xplan.display('','','all +outline +hint_report'));

示例#3：

PLAN_TABLE_OUTPUT
----------------------------------------------------------------------------------------------------
Plan hash value: 247834218

---------------------------------------------------------------------------------------------
| Id  | Operation                    | Name         | Rows  | Bytes | Cost (%CPU)| Time     |
---------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT             |              |    10 |  1170 |    58   (0)| 00:00:01 |
|   1 |  NESTED LOOPS                |              |    10 |  1170 |    58   (0)| 00:00:01 |
|   2 |   NESTED LOOPS               |              |    10 |  1170 |    58   (0)| 00:00:01 |
|*  3 |    TABLE ACCESS FULL         | TABLE_2      |    10 |    80 |    48   (0)| 00:00:01 |
|*  4 |    INDEX UNIQUE SCAN         | SYS_C0010147 |     1 |       |     0   (0)| 00:00:01 |
|   5 |   TABLE ACCESS BY INDEX ROWID| TABLE_1      |     1 |   109 |     1   (0)| 00:00:01 |
---------------------------------------------------------------------------------------------

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

   1 - SEL$535BA485
   3 - SEL$535BA485 / T2@SEL$3
   4 - SEL$535BA485 / T@SEL$3
   5 - SEL$535BA485 / T@SEL$3

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

  /*+
      BEGIN_OUTLINE_DATA
      NLJ_BATCHING(@"SEL$535BA485" "T"@"SEL$3")
      USE_NL(@"SEL$535BA485" "T"@"SEL$3")
      LEADING(@"SEL$535BA485" "T2"@"SEL$3" "T"@"SEL$3")
      INDEX(@"SEL$535BA485" "T"@"SEL$3" ("TABLE_1"."COL1"))
      FULL(@"SEL$535BA485" "T2"@"SEL$3")
      OUTLINE(@"SEL$3")
      OUTLINE(@"SEL$4")
      MERGE(@"SEL$3" >"SEL$4")
      OUTLINE(@"SEL$37633EB5")
      OUTLINE(@"SEL$2")
      MERGE(@"SEL$37633EB5" >"SEL$2")
      OUTLINE(@"SEL$BB1798A6")
      OUTLINE(@"SEL$1")
      MERGE(@"SEL$BB1798A6" >"SEL$1")
      OUTLINE_LEAF(@"SEL$535BA485")
      ALL_ROWS
      OPT_PARAM('_optimizer_nlj_hj_adaptive_join' 'false')
      OPT_PARAM('_optimizer_strans_adaptive_pruning' 'false')
      OPT_PARAM('_px_adaptive_dist_method' 'off')
      DB_VERSION('19.1.0')
      OPTIMIZER_FEATURES_ENABLE('19.1.0')
      IGNORE_OPTIM_EMBEDDED_HINTS
      END_OUTLINE_DATA
  */

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

   3 - filter("T2"."COL2"=TO_NUMBER(:BIND))
   4 - access("T"."COL1"="T2"."COL1")

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

   1 - (#keys=0) "T"."COL1"[NUMBER,22], "T"."COL2"[NUMBER,22],
       "T"."COL3"[VARCHAR2,100]
   2 - (#keys=0) "T".ROWID[ROWID,10], "T"."COL1"[NUMBER,22]
   3 - "T2"."COL1"[NUMBER,22]
   4 - "T".ROWID[ROWID,10], "T"."COL1"[NUMBER,22]
   5 - "T"."COL2"[NUMBER,22], "T"."COL3"[VARCHAR2,100]

Hint Report (identified by operation id / Query Block Name / Object Alias):
Total hints for statement: 1
---------------------------------------------------------------------------

   3 -  SEL$535BA485 / T2@SEL$3
           -  NO_INDEX(b.a.t2)

最后，关于DBFiddle的所有示例： https ://dbfiddle.uk/?rdbms=oracle_21&fiddle=5d4a44a13cb5ca3920794caedeaab44d