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POExplain Plan Cost vs Execution Time
 

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    <p>Before, I have found the "Cost" in the execution plan to be a good indicator of relative execution time. Why is this case different? Am I a fool for thinking the execution plan has relevance? What specifically can I try to improve v_test performance?</p> <p>Thank you.</p> <p>Using Oracle 10g I have a simple query view defined below</p> <pre><code> create or replace view v_test as select distinct u.bo_id as bo_id, upper(trim(d.dept_id)) as dept_id from cust_bo_users u join cust_bo_roles r on u.role_name=r.role_name join cust_dept_roll_up_tbl d on (r.region is null or trim(r.region)=trim(d.chrgback_reg)) and (r.prod_id is null or trim(r.prod_id)=trim(d.prod_id)) and (r.div_id is null or trim(r.div_id)=trim(d.div_id )) and (r.clus_id is null or trim(r.clus_id )=trim( d.clus_id)) and (r.prod_ln_id is null or trim(r.prod_ln_id)=trim(d.prod_ln_id)) and (r.dept_id is null or trim(r.dept_id)=trim(d.dept_id)) </code></pre> <p>defined to replace the following view</p> <pre><code> create or replace view v_bo_secured_detail select distinct Q.BO_ID, Q.DEPT_ID from (select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'REGION' and trim(R.REGION) = UPPER(trim(D.CHRGBACK_REG)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'RG_PROD' and trim(R.REGION) = UPPER(trim(D.CHRGBACK_REG)) and trim(R.PROD_ID) = UPPER(trim(D.PROD_ID)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'PROD' and trim(R.PROD_ID) = UPPER(trim(D.PROD_ID)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'DIV' and trim(R.DIV_ID) = UPPER(trim(D.DIV_ID)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'RG_DIV' and trim(R.REGION) = UPPER(trim(D.CHRGBACK_REG)) and trim(R.DIV_ID) = UPPER(trim(D.DIV_ID)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'CLUS' and trim(R.CLUS_ID) = UPPER(trim(D.CLUS_ID)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'RG_CLUS' and trim(R.REGION) = UPPER(trim(D.CHRGBACK_REG)) and trim(R.CLUS_ID) = UPPER(trim(D.CLUS_ID)) union all select U.BO_ID BO_ID, UPPER(trim(D.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R, CUST_DEPT_ROLL_UP_TBL D where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'PROD_LN' and trim(R.PROD_LN_ID) = UPPER(trim(D.PROD_LN_ID)) union all select U.BO_ID BO_ID, UPPER(trim(R.DEPT_ID)) DEPT_ID from CUST_BO_USERS U, CUST_BO_ROLES R where U.ROLE_NAME = R.ROLE_NAME and R.ROLE_LEVEL = 'DEPT') Q </code></pre> <p>with the goal of removing the dependency on the ROLE_LEVEL column.</p> <p>The execution plan for v_test is significantly lower than v_bo_secured_detail for simple</p> <pre><code>select * from &lt;view&gt; where bo_id='value' </code></pre> <p>queries. And is significantly lower when used in a real world query</p> <pre><code> select CT_REPORT.RPT_KEY, CT_REPORT_ENTRY.RPE_KEY, CT_REPORT_ENTRY.CUSTOM16, Exp_Sub_Type.value, min(CT_REPORT_PAYMENT_CONF.PAY_DATE), CT_REPORT.PAID_DATE from CT_REPORT, &lt;VIEW&gt; SD, CT_REPORT_ENTRY, CT_LIST_ITEM_LANG Exp_Sub_Type, CT_REPORT_PAYMENT_CONF, CT_STATUS_LANG Payment_Status where (CT_REPORT_ENTRY.RPT_KEY = CT_REPORT.RPT_KEY) and (Payment_Status.STAT_KEY = CT_REPORT.PAY_KEY) and (Exp_Sub_Type.LI_KEY = CT_REPORT_ENTRY.CUSTOM9 and Exp_Sub_Type.LANG_CODE = 'en') and (CT_REPORT.RPT_KEY = CT_REPORT_PAYMENT_CONF.RPT_KEY) and (SD.BO_ID = 'JZHU9') and (SD.DEPT_ID = UPPER(CT_REPORT_ENTRY.CUSTOM5)) and (Payment_Status.name = 'Payment Confirmed' and (Payment_Status.LANG_CODE = 'en') and CT_REPORT.PAID_DATE &gt; to_date('01/01/2008', 'mm/dd/yyyy') and Exp_Sub_Type.value != 'Korea') group by CT_REPORT.RPT_KEY, CT_REPORT_ENTRY.RPE_KEY, CT_REPORT_ENTRY.CUSTOM16, Exp_Sub_Type.value, CT_REPORT.PAID_DATE </code></pre> <p>The execution times are WILDLY different. The v_test view taking 15 hours, and the v_bo_secured_detail taking a few seconds.</p> <hr> <p><strong>Thank you all who responded</strong></p> <p>This is one to remember for me. The places where the theory and mathematics of the expressions meets the reality of hardware based execution. Ouch.</p>
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