ORACLE 11204, SOLARIS

如下：原始写法，where 条件中，有 OR 条件，这时，索引　IDX_BD_LOTMASTER_NO　走全索引扫描，导致效率非常低，

-bash-3.2$ sqlplus

SQL*Plus: Release 11.2.0.4.0 Production on Wed Aug 16 09:17:30 2017

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Enter password:

Connected to:

Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production

With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,

Data Mining and Real Application Testing options

SQL>set autot trace exp stat;

SQL>SELECT * FROM

2  (SELECT t0.FNUMBER FNUMBER, t0_L.FNAME FNAME, t0.FLOTID FLOTID

FROM T_BD_LOTMASTER T0

LEFT OUTER JOIN T_BD_LOTMASTER_L T0_L ON (t0.FLOTID = t0_L.FLOTID AND t0_L.FLocaleId = 2052)

WHERE (((t0.FUSEORGID IN (100132)) AND t0.FBIZTYPE = '1')

AND ((t0.FNUMBER LIKE N'8%') OR

(t0_L.FNAME LIKE N'8%') ) ) ORDER BY t0.FNUMBER ASC) WHERE ROWNUM <= 5   3    4    5    6    7  ;

Elapsed: 00:00:30.64

Execution Plan

----------------------------------------------------------

Plan hash value: 3360367673

---------------------------------------------------------------------------------------------------------

| Id  | Operation                       | Name                  | Rows  | Bytes | Cost (%CPU)| Time     |

---------------------------------------------------------------------------------------------------------

|   0 | SELECT STATEMENT                |                       |     5 |  2635 | 67582   (1)| 00:01:16 |

|*  1 |  COUNT STOPKEY                  |                       |       |       |            |          |

|   2 |   VIEW                          |                       |     5 |  2635 | 67582   (1)| 00:01:16 |

|*  3 |    FILTER                       |                       |       |       |            |          |

|   4 |     NESTED LOOPS OUTER          |                       |     5 |   465 | 67582   (1)| 00:01:16 |

|*  5 |      TABLE ACCESS BY INDEX ROWID| T_BD_LOTMASTER        |  1860K|    85M| 35032   (1)| 00:00:40 |

|   6 |     INDEX FULL SCAN           | IDX_BD_LOTMASTER_NO | 35968 |       |   309   (2)| 00:00:01 |

|*  7 |      TABLE ACCESS BY INDEX ROWID| T_BD_LOTMASTER_L      |     1 |    45 |     3   (0)| 00:00:01 |

|*  8 |       INDEX RANGE SCAN          | IDX_BD_LOTMASTER_L_ID |     1 |       |     2   (0)| 00:00:01 |

---------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

1 - filter(ROWNUM<=5)

3 - filter("T0"."FNUMBER" LIKE U'8%' OR "T0_L"."FNAME" LIKE U'8%')

5 - filter("T0"."FUSEORGID"=100132 AND "T0"."FBIZTYPE"='1')

7 - filter("T0_L"."FLOCALEID"(+)=2052)

8 - access("T0"."FLOTID"="T0_L"."FLOTID"(+))

Statistics

----------------------------------------------------------

1  recursive calls

0  db block gets

9352435  consistent gets

113  physical reads

724  redo size

809  bytes sent via SQL*Net to client

520  bytes received via SQL*Net from client

2  SQL*Net roundtrips to/from client

0  sorts (memory)

0  sorts (disk)

3  rows processed

SQL>

--去掉 OR 条件后，IDX_BD_LOTMASTER_NO　走范围扫描，效率高多了，问：为何多了　OR  条件后，索引就走全扫描？SQL>SELECT * FROM

2    (SELECT t0.FNUMBER FNUMBER, t0_L.FNAME FNAME, t0.FLOTID FLOTID

FROM T_BD_LOTMASTER T0

LEFT OUTER JOIN T_BD_LOTMASTER_L T0_L ON (t0.FLOTID = t0_L.FLOTID AND t0_L.FLocaleId = 2052 )

WHERE (((t0.FUSEORGID IN (100132)) AND t0.FBIZTYPE = '1')

AND ( (t0.FNUMBER LIKE N'8%')) ) ORDER BY t0.FNUMBER ASC)  3    4    5    6  ;

Elapsed: 00:00:00.01

Execution Plan

----------------------------------------------------------

Plan hash value: 1298050334

------------------------------------------------------------------------------------------------------

| Id  | Operation                    | Name                  | Rows  | Bytes | Cost (%CPU)| Time     |

------------------------------------------------------------------------------------------------------

|   0 | SELECT STATEMENT             |                       |   431 | 40083 |  2701   (1)| 00:00:04 |

|   1 |  NESTED LOOPS OUTER          |                       |   431 | 40083 |  2701   (1)| 00:00:04 |

|*  2 |   TABLE ACCESS BY INDEX ROWID| T_BD_LOTMASTER        |   431 | 20688 |  1401   (1)| 00:00:02 |

|*  3 |   INDEX RANGE SCAN          | IDX_BD_LOTMASTER_NO   |  1435 |       |    15   (0)| 00:00:01 |

|*  4 |   TABLE ACCESS BY INDEX ROWID| T_BD_LOTMASTER_L      |     1 |    45 |     3   (0)| 00:00:01 |

|*  5 |    INDEX RANGE SCAN          | IDX_BD_LOTMASTER_L_ID |     1 |       |     2   (0)| 00:00:01 |

------------------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):

---------------------------------------------------

2 - filter("T0"."FUSEORGID"=100132 AND "T0"."FBIZTYPE"='1')

3 - access("T0"."FNUMBER" LIKE U'8%')

filter("T0"."FNUMBER" LIKE U'8%')

4 - filter("T0_L"."FLOCALEID"(+)=2052)

5 - access("T0"."FLOTID"="T0_L"."FLOTID"(+))

Statistics

----------------------------------------------------------

1  recursive calls

0  db block gets

22  consistent gets

0  physical reads

0  redo size

809  bytes sent via SQL*Net to client

520  bytes received via SQL*Net from client

2  SQL*Net roundtrips to/from client

0  sorts (memory)

0  sorts (disk)

3  rows processed