[20180926]查询相似索引.txt

[20180926]查询相似索引.txt

--//有时候在表上建立索引比如A,B字段,可能又建立B字段索引,甚至A字段索引以及B,A字段索引,或者还建立C,A字段索引,
--//需要有1个脚本查询这些索引,可能还有必要删除一些索引,统一协调建立合适的索引.
--//优化需要,做一个记录.

1.环境:
SCOTT@test01p> @ ver1
PORT_STRING                    VERSION        BANNER                                                                               CON_ID
------------------------------ -------------- -------------------------------------------------------------------------------- ----------
IBMPC/WIN_NT64-9.1.0           12.1.0.1.0     Oracle Database 12c Enterprise Edition Release 12.1.0.1.0 - 64bit Production              0

2.建立测试例子:
SCOTT@test01p> create table t (a number,b number,c number);
Table created.

SCOTT@test01p> create index i_t_a_b on t(a,b);
Index created.

SCOTT@test01p> create index i_t_c_b on t(c,b);
Index created.

--//网上找到的例子:
SELECT TABLE_OWNER, TABLE_NAME, INDEX_NAME, COLUMN_NAME
  FROM ALL_IND_COLUMNS
 WHERE COLUMN_POSITION = 1
   AND TABLE_OWNER     = UPPER ('&&1')
   AND (TABLE_OWNER, TABLE_NAME, COLUMN_NAME) IN (
        SELECT TABLE_OWNER, TABLE_NAME, COLUMN_NAME
          FROM (
                SELECT TABLE_OWNER, TABLE_NAME, COLUMN_NAME, COUNT (*) TCOUNT
                  FROM ALL_IND_COLUMNS
                 WHERE TABLE_OWNER NOT IN ('SYS','SYSTEM','OUTLN','DBSNMP')
                HAVING COUNT (*)       > 1
 GROUP BY TABLE_OWNER, TABLE_NAME, COLUMN_NAME))
 ORDER BY TABLE_OWNER, TABLE_NAME, COLUMN_NAME, INDEX_NAME;

--//实际上这个例子在我们生产系统根本无法执行,表N多,1个小时都没有查询出来.而且像上面建立的索引是无法找到的.
--//因为它仅仅针对COLUMN_POSITION = 1的情况.

--//使用with改写如下:
/* Formatted on 2018/9/25 22:19:20 (QP5 v5.227.12220.39754) */
WITH t1
     AS (SELECT TABLE_OWNER
               ,TABLE_NAME
               ,INDEX_NAME
               ,COLUMN_NAME
               ,COLUMN_POSITION
           FROM ALL_IND_COLUMNS
          WHERE TABLE_OWNER = UPPER ('&&1'))
    ,t2
     AS (  SELECT DISTINCT TABLE_OWNER
                          ,TABLE_NAME
                          ,INDEX_NAME
                          ,COLUMN_NAME
             FROM t1
            WHERE (TABLE_OWNER, TABLE_NAME, COLUMN_NAME) IN
                     (SELECT TABLE_OWNER, TABLE_NAME, COLUMN_NAME
                        FROM (  SELECT TABLE_OWNER
                                      ,TABLE_NAME
                                      ,COLUMN_NAME
                                      ,COUNT (*) TCOUNT
                                  FROM T1
                                HAVING COUNT (*) > 1
                              GROUP BY TABLE_OWNER, TABLE_NAME, COLUMN_NAME))
         ORDER BY TABLE_OWNER
                 ,TABLE_NAME
                 ,COLUMN_NAME
                 ,INDEX_NAME)
    ,t3
     AS (  SELECT TABLE_OWNER
                 ,TABLE_NAME
                 ,INDEX_NAME
                 ,LISTAGG (column_name, ', ')
                     WITHIN GROUP (ORDER BY column_position)
                     AS column_group
             FROM t1
         GROUP BY TABLE_OWNER, TABLE_NAME, INDEX_NAME)
SELECT TABLE_OWNER
      ,TABLE_NAME
      ,INDEX_NAME
      ,column_group
  FROM t3
 WHERE (TABLE_OWNER, TABLE_NAME, INDEX_NAME) IN
          (SELECT TABLE_OWNER, TABLE_NAME, INDEX_NAME FROM t2);

TABLE_OWNER          TABLE_NAME           INDEX_NAME           COLUMN_GROUP
-------------------- -------------------- -------------------- ----------------------
SCOTT                T                    I_T_A_B              A, B
SCOTT                T                    I_T_C_B              C, B

--//补充:在生产系统使用不到1秒就执行完成.
--//换一个参数OE.
Enter value for 1: OE
old   8:           WHERE TABLE_OWNER = UPPER ('&&1'))
new   8:           WHERE TABLE_OWNER = UPPER ('OE'))

TABLE_OWNER          TABLE_NAME           INDEX_NAME           COLUMN_GROUP
-------------------- -------------------- -------------------- -------------------------------------------------
OE                   INVENTORIES          INVENTORY_IX         WAREHOUSE_ID, PRODUCT_ID
OE                   INVENTORIES          INV_PRODUCT_IX       PRODUCT_ID
OE                   ORDER_ITEMS          ITEM_ORDER_IX        ORDER_ID
OE                   ORDER_ITEMS          ORDER_ITEMS_PK       ORDER_ID, LINE_ITEM_ID
OE                   ORDER_ITEMS          ORDER_ITEMS_UK       ORDER_ID, PRODUCT_ID
OE                   ORDER_ITEMS          ITEM_PRODUCT_IX      PRODUCT_ID
6 rows selected.

--//如果使用网上的脚本结果如下:

SCOTT@test01p> SELECT TABLE_OWNER, TABLE_NAME, INDEX_NAME, COLUMN_NAME
  2    FROM ALL_IND_COLUMNS
  3   WHERE COLUMN_POSITION = 1
  4     AND TABLE_OWNER     = UPPER ('&&1')
  5     AND (TABLE_OWNER, TABLE_NAME, COLUMN_NAME) IN (
  6             SELECT TABLE_OWNER, TABLE_NAME, COLUMN_NAME
  7               FROM (
  8                             SELECT TABLE_OWNER, TABLE_NAME, COLUMN_NAME, COUNT (*) TCOUNT
  9                               FROM ALL_IND_COLUMNS
 10                              WHERE TABLE_OWNER NOT IN ('SYS','SYSTEM','OUTLN','DBSNMP')
 11                             HAVING COUNT (*)       > 1
 12   GROUP BY TABLE_OWNER, TABLE_NAME, COLUMN_NAME))
 13   ORDER BY TABLE_OWNER, TABLE_NAME, COLUMN_NAME, INDEX_NAME;
old   4:    AND TABLE_OWNER     = UPPER ('&&1')
new   4:    AND TABLE_OWNER     = UPPER ('OE')
TABLE_OWNER          TABLE_NAME           INDEX_NAME           COLUMN_NAME
-------------------- -------------------- -------------------- --------------------
OE                   INVENTORIES          INV_PRODUCT_IX       PRODUCT_ID
OE                   ORDER_ITEMS          ITEM_ORDER_IX        ORDER_ID
OE                   ORDER_ITEMS          ORDER_ITEMS_PK       ORDER_ID
OE                   ORDER_ITEMS          ORDER_ITEMS_UK       ORDER_ID
OE                   ORDER_ITEMS          ITEM_PRODUCT_IX      PRODUCT_ID

--//1.结果不同,存在遗漏.
--//2.明显感觉执行很慢.
--//3.显示不直观.