Bind variables and function based index
Date: Wed, 7 May 2008 21:56:56 -0700
In continuation with my earlier post
This is the query. Couple of things I noticed about this is that this query does not use the Function based index created on suggested_vendor_name and also the explain plan repeats itslef (it does the same steps twice). Attached is the explain plan so that you see what I mean.
On the other hand if I replace these bind variables with actual values, it does use the index and no repeatition (in explain plan)
XXDL_REQ_WEB_INQUIRY.DECODE_PERSON_NAME(RH.PREPARER_ID) ORIGINATOR_NAME, RL.SUGGESTED_VENDOR_NAME, RH.CREATION_DATE, RH.AUTHORIZATION_STATUS, DECODE(NVL(PH.PO_HEADER_ID,'1'),'1',' ',NVL(PH.AUTHORIZATION_STATUS, 'INCOMPLETE')) PO_STATUS
PO.PO_REQUISITION_LINES_ALL RL, PO.PO_REQUISITION_HEADERS_ALL RH, PO.PO_REQ_DISTRIBUTIONS_ALL RD, PO.PO_DISTRIBUTIONS_ALL PD, PO.PO_HEADERS_ALL PH, MTL_CATEGORIES MC WHERE 1=1 AND UPPER(RL.SUGGESTED_VENDOR_NAME) LIKE UPPER(:B7 || '%') AND RH.REQUISITION_HEADER_ID = RL.REQUISITION_HEADER_ID+0 AND
RL.REQUISITION_LINE_ID = RD.REQUISITION_LINE_ID AND RD.DISTRIBUTION_ID = PD.REQ_DISTRIBUTION_ID(+) AND RD.EXPENDITURE_TYPE = NVL(:B6 , RD.EXPENDITURE_TYPE) AND PD.PO_HEADER_ID = PH.PO_HEADER_ID(+) AND RH.CREATION_DATE BETWEEN :B5 AND :B4 AND RH.AUTHORIZATION_STATUS=DECODE(:B3
,'1',RH.AUTHORIZATION_STATUS,:B3 ) AND RL.CATEGORY_ID = MC.CATEGORY_ID AND
MC.SEGMENT1||'' = NVL(:B2 ,MC.SEGMENT1) AND MC.SEGMENT2||'' = NVL(:B1 ,
MC.SEGMENT2) AND ((MC.ATTRIBUTE9 = 'Y') OR (RH.PREPARER_ID =
(XXDL_REQ_WEB_INQUIRY.ISAPPROVER(RH.REQUISITION_HEADER_ID, FND_GLOBAL.EMPLOYEE_ID) = 'Y')) ORDER BY RH.CREATION_DATE DESC On Tue, May 6, 2008 at 5:56 PM, Mark Brinsmead <pythianbrinsmead_at_gmail.com> wrote:
> Using bind variables rather than literals can alter the cardinality
> estimates used by the CBO, and that can alter the execution plan.
> It might be helpful to provide the actual query, or at least the execution
> On Tue, May 6, 2008 at 5:54 PM, Kumar Madduri <ksmadduri_at_gmail.com> wrote:
> > Hi
> > Is there any restriction with bind variables and function based indexes.
> > I noticed that if I have literals fbi is being used but if I replace that
> > with bind variables then fbi is not used. DB version is 10.2.0.1. You
> > cant seem to force it to use FBI through hints also. As I am investigating
> > this, I thought of posting here to see if there are any known issues or
> > restrictions that prevent function based indexes usage with bind variables.
> > QUERY_REWRITE_INTEGRITY is set to trusted and query_rewrite_enabled is
> > true.
> > thank you
> > - kumar
> -- Mark Brinsmead
> Senior DBA,
> The Pythian Group
Received on Wed May 07 2008 - 23:56:56 CDT