Odd behavior of function-based index after DB upgrade

From: Hameed, Amir <Amir.Hameed_at_xerox.com>
Date: Wed, 5 Oct 2011 19:24:34 -0400
Message-ID: <304F58144267C5439E733532ABC9A3A112F47CE2_at_USA0300MS02.na.xerox.net>

We have recently upgraded one of our Oracle ERP (11i.10.2) systems database from 10.2.0.4 to 11.1.0.7. After the upgrade, we are seeing some odd behavior on a custom job that was working fine prior to the upgrade. Prior to the upgrade, the job was using a function-based index, however, it has stopped using that index after the upgrade.  

select * from dba_ind_expressions where
table_name='TXRIOH0_INV_OUTBOUND_HDRS_ALL' ;  

OWNER  INDEX_NAME                     TABLE_NAME
COLUMN_EXPRESSION                        COLUMN_POSITION

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

XRX    TXRIOH0_INV_OUTBOUND_HDRS_IDX3 TXRIOH0_INV_OUTBOUND_HDRS_ALL
LPAD(NVL("VOUCHER_NO",'0'),7,'0')                      1

XRX    TXRIOH0_INV_OUTBOUND_HDRS_IDX3 TXRIOH0_INV_OUTBOUND_HDRS_ALL
NVL("SYSTEM",'1')                                      2

 

Below is one of the statements that are supposed to use this index:

SELECT LEGACY_VENDOR_NO FROM TXRIOH0_INV_OUTBOUND_HDRS_ALL WHERE LPAD(NVL(VOUCHER_NO,0),7,'0') = :B2 AND NVL(SYSTEM,1) = NVL(:B1 ,1) AND BATCH_STATUS NOT IN ('CONFIRMED','PAID','RECEIVED') ;  

The explain plan shows that the statement is doing FTS on the table:

---

---

| Id  | Operation           | Name                          | Starts |

E-Rows | A-Rows | A-Time | Buffers | Reads |

---

---

|   0 | SELECT STATEMENT    |                               |      1 |
|      0 |00:01:03.22 |     359K|    359K|

|   1 |  CONCATENATION      |                               |      1 |
|      0 |00:01:03.22 |     359K|    359K|

|*  2 |   FILTER            |                               |      1 |
|      0 |00:00:00.01 |       0 |      0 |

|*  3 |    TABLE ACCESS FULL| TXRIOH0_INV_OUTBOUND_HDRS_ALL |      0 |
1 |      0 |00:00:00.01 |       0 |      0 |

|*  4 |   FILTER            |                               |      1 |
|      0 |00:01:03.22 |     359K|    359K|

|*  5 |    TABLE ACCESS FULL| TXRIOH0_INV_OUTBOUND_HDRS_ALL |      1 |
1 |      0 |00:01:03.22 |     359K|    359K|



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

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


 

We re-ran statistics on the table but it did not help. The optimizer kept ignoring the index. I then set the optimizer mode to rule and the statement started using the index. I was able to create a test table and define a function-based index on it and it worked fine. So, I am not sure why the optimizer keeps ignoring this index. Has anyone run into a similar issue with 11g? There are lots of Oracle defined/standard function-based in the Oracle EBS database and they seemed to be working fine.  

Thanks

Amir  

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Received on Wed Oct 05 2011 - 18:24:34 CDT