| 今天看SQL执行计划时发现一条额外的Predicate Information。一时找不到该Predicate Information来自何处。一般情况下对Oracletable或者View增加行授权（即调用dbms_rls.add_policy创建policy后），对该表的查询会自动增加Predicate Information。 但是这次查找DBA_POLICIES视图也没找到相关policy。不知道大家有没遇到这种情况。 附上代码如下： EXPLAIN PLAN FOR SELECT EXPIRATION_DATE, FREEZE_FLAG, LAST_COUNT_DATE, LOCATION_TYPE, QTY_IN_TRANSIT, QTY_ONHAND, QTY_RESERVED, RECEIPT_DATE, AVAILABILITY_CONTROL_ID, ROTABLE_PART_POOL_ID FROM INVENTORY_PART_IN_STOCK_TAB WHERE PART_NO = :B8 AND CONTRACT = :B7 AND CONFIGURATION_ID = :B6 AND LOCATION_NO = :B5 AND LOT_BATCH_NO = :B4 AND SERIAL_NO = :B3 AND ENG_CHG_LEVEL = :B2 AND WAIV_DEV_REJ_NO = :B1 ; COMMIT; SELECT * FROM TABLE(dbms_xplan.display) ; 执行计划及Predicate Information如下： Plan hash value: 1802187973 ------------------------------------------------------------------------------------------------------------ | Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time | ------------------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 1 | 95 | 4 (0)| 00:00:01 | |* 1 | TABLE ACCESS BY INDEX ROWID| INVENTORY_PART_IN_STOCK_TAB | 1 | 95 | 4 (0)| 00:00:01 | |* 2 | INDEX RANGE SCAN | INVENTORY_PART_IN_STOCK_PX01 | 3 | | 3 (0)| 00:00:01 | ------------------------------------------------------------------------------------------------------------ Predicate Information (identified by operation id): --------------------------------------------------- 1 - filter("PART_NO"=:B8 AND "LOCATION_NO"=:B5 AND "CONTRACT"=:B7 AND "ENG_CHG_LEVEL"=:B2 AND SUBSTR("INVENTORY_PART_IN_STOCK_TAB"."PART_NO",1,17)=SUBSTR(:B8,1,17) AND "CONFIGURATION_ID"=:B6 AND "LOT_BATCH_NO"=:B4 AND "SERIAL_NO"=:B3) 2 - access("WAIV_DEV_REJ_NO"=:B1) 其中SUBSTR("INVENTORY_PART_IN_STOCK_TAB"."PART_NO",1,17)=SUBSTR(:B8,1,17) 为额外的谓词信息。 这条谓词信息足以改变该SQL的执行计划，从原本主键的INDEX UNIQUE SCAN 变成一个普通索引的INDEX RANGE SCAN |