Heavy Query....

Question

Hi ,
I have a problem with one query , when i run this query on my database in first two executions it is Ok and having a lower Buffer Gets and Physical Reads but after two or three executions it conceeds 50k+ Buffer Gets and 12k + PR.
The table on which this query runs is a highly updatable table on our production server.
Query:-
SELECT * FROM
     SELECT
          ETO_OFR_DISPLAY_ID ETO_OFR_ID, ETO_OFR_TYP, ETO_OFR_TITLE, TO_CHAR(ETO_OFR_DATE,'Dy, dd Mon yyyy HH24:MI:SS') AS OFFER_DATE, ETO_OFR_DATE,
          NVL(SUBSTR(ETO_OFR_DESC,1,INSTR(ETO_OFR_DESC,CHR(13)||CHR(10),1,5)),ETO_OFR_DESC) ETO_OFR_DESC, ETO_OFR_QTY,
          COALESCE(ETO_OFR_IMAGE_PATH1,ETO_OFR_IMAGE_PATH2,ETO_OFR_IMAGE_PATH3) ETO_OFR_IMAGE, ETO_OFR_QLTY, FK_GLCAT_CAT_ID, ETO_OFR_COMPANYNAME GLUSR_USR_COMPANYNAME,
          ETO_OFR_GL_COUNTRY_NAME GL_COUNTRY_NAME, ETO_OFR_COMPANY_TSCODE TRUSTSEAL_COMPANY_TSCODE, ETO_OFR_GLUSR_USERNAME GLUSR_USR_USERNAME
     FROM
          ETO_OFR
     WHERE
          ETO_OFR_TYP = 'B' AND ETO_OFR_APPROV = 'A' AND ETO_OFR_PREFERED_FK_GLUSR_ID IS NULL ORDER BY ETO_OFR_DATE DESC
     ) WHERE ROWNUM < 6
Every Time This query Use Same Index.
Rahul Sharma
Edited by: Rahul Sharma on Mar 14, 2011 2:45 AM
Edited by: Rahul Sharma on Mar 14, 2011 3:03 AM
Edited by: Rahul Sharma on Mar 14, 2011 4:09 AM

Answer 1

Please read and followup SQL and PL/SQL FAQ
item 3.
Also please format your query prior to posting it.
Sybrand Bakker
Senior Oracle DBA