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PORewrite Query without using correlated subqueries
 

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  1. PORewrite Query without using correlated subqueries
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    <p>Using Oracle 10gR2 on LINUX, I'm trying to tune the following query.<br> I'm pretty sure that getting rid of the correlated subqueries and the possible use of some analytic functions may be the optimal way to go, but I'm just not getting it -- especially with the nested correlated subquery that selects on the MAX(TABLE_2.NOTE_DATE). Any help would be much appreciated. Thanks.</p> <pre><code>EXPLAIN PLAN FOR SELECT TABLE_4.INCIDENT_TYPE, TABLE_4.POC_CONTACT, (SELECT TABLE_2.NOTE_DATE || ' ' || TABLE_1.USER_FIRST_NAME || ' ' || TABLE_1.USER_LAST_NAME || ' : ' || TABLE_2.OTHER_HELP_NOTES FROM TABLE_1, TABLE_2 WHERE TABLE_2.USER_ID = TABLE_1.USER_ID AND TABLE_2.REC_ID = TABLE_4.REC_ID AND TABLE_2.NOTE_DATE = (SELECT MAX(TABLE_2.NOTE_DATE) FROM TABLE_2 WHERE TABLE_2.REC_ID = TABLE_4.REC_ID AND TABLE_2.NOTE_DATE &lt;= TABLE_4.REPORT_DATE)) AS SUM_OF_SHORTAGE, (SELECT TABLE_3.NOTE_DATE || ' ' || TABLE_1.USER_FIRST_NAME || ' ' || TABLE_1.USER_LAST_NAME || ' : ' || TABLE_3.HELP_NOTES FROM TABLE_1, TABLE_3 WHERE TABLE_3.USER_ID = TABLE_1.USER_ID AND TABLE_3.REC_ID = TABLE_4.REC_ID AND TABLE_3.NOTE_DATE = (SELECT MAX(TABLE_3.NOTE_DATE) FROM TABLE_3 WHERE TABLE_3.REC_ID = TABLE_4.REC_ID AND TABLE_3.NOTE_DATE &lt;= TABLE_4.REPORT_DATE)) AS HELP_NOTES, TABLE_4.REPORT_NUM FROM TABLE_4 WHERE TABLE_4.SITE_ID = '1'; @C:\ORACLE\PRODUCT\11.2.0\CLIENT_1\RDBMS\ADMIN\UTLXPLS.SQL; PLAN_TABLE_OUTPUT ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ PLAN HASH VALUE: 4036328474 ------------------------------------------------------------------------------------------------------------ | ID | OPERATION | NAME | ROWS | BYTES | COST (%CPU)| TIME | ------------------------------------------------------------------------------------------------------------ | 0 | SELECT STATEMENT | | 13009 | 2286K| 449 (2)| 00:00:06 | |* 1 | FILTER | | | | | | | 2 | NESTED LOOPS | | 3 | 612 | 8 (0)| 00:00:01 | | 3 | TABLE ACCESS BY INDEX ROWID| TABLE_2 | 3 | 552 | 5 (0)| 00:00:01 | |* 4 | INDEX RANGE SCAN | IX_TABLE_2_REC_ID | 3 | | 1 (0)| 00:00:01 | | 5 | TABLE ACCESS BY INDEX ROWID| TABLE_1 | 1 | 20 | 1 (0)| 00:00:01 | |* 6 | INDEX UNIQUE SCAN | TABLE_1_PK | 1 | | 0 (0)| 00:00:01 | | 7 | SORT AGGREGATE | | 1 | 13 | | | |* 8 | TABLE ACCESS BY INDEX ROWID| TABLE_2 | 1 | 13 | 5 (0)| 00:00:01 | |* 9 | INDEX RANGE SCAN | IX_TABLE_2_REC_ID | 3 | | 1 (0)| 00:00:01 | |* 10 | FILTER | | | | | | |* 11 | HASH JOIN | | 17 | 4063 | 482 (2)| 00:00:06 | |* 12 | TABLE ACCESS FULL | TABLE_3 | 17 | 3723 | 474 (2)| 00:00:06 | | 13 | TABLE ACCESS FULL | TABLE_1 | 1504 | 30080 | 8 (0)| 00:00:01 | | 14 | SORT AGGREGATE | | 1 | 13 | | | |* 15 | TABLE ACCESS FULL | TABLE_3 | 1 | 13 | 474 (2)| 00:00:06 | |* 16 | TABLE ACCESS FULL | TABLE_4 | 13009 | 2286K| 449 (2)| 00:00:06 | ------------------------------------------------------------------------------------------------------------ PREDICATE INFORMATION (IDENTIFIED BY OPERATION ID): --------------------------------------------------- 1 - FILTER("TABLE_2"."NOTE_DATE"= (SELECT /*+ */ MAX("TABLE_2"."NOTE_DATE") FROM "TABLE_2" "TABLE_2" WHERE "TABLE_2"."REC_ID"=:B1 AND "TABLE_2"."NOTE_DATE"&lt;=:B2)) 4 - ACCESS("TABLE_2"."REC_ID"=:B1) 6 - ACCESS("TABLE_2"."USER_ID"="TABLE_1"."USER_ID") 8 - FILTER("TABLE_2"."NOTE_DATE"&lt;=:B1) 9 - ACCESS("TABLE_2"."REC_ID"=:B1) 10 - FILTER("TABLE_3"."NOTE_DATE"= (SELECT /*+ */ MAX("TABLE_3"."NOTE_DATE") FROM "TABLE_3" "TABLE_3" WHERE "TABLE_3"."REC_ID"=:B1 AND "TABLE_3"."NOTE_DATE"&lt;=:B2)) 11 - ACCESS("TABLE_3"."USER_ID"="TABLE_1"."USER_ID") 12 - FILTER("TABLE_3"."REC_ID"=:B1) 15 - FILTER("TABLE_3"."REC_ID"=:B1 AND "TABLE_3"."NOTE_DATE"&lt;=:B2) 16 - FILTER("TABLE_4"."SITE_ID"=1) 41 ROWS SELECTED </code></pre> <p>Breaking down this query -- the key problem seems to be the following:</p> <pre><code>select REC_ID, TO_CHAR(REPORT_DATE,'DD-MON-YY HH:MI:SS') REPORT_DATE, (SELECT MAX(TABLE_2.note_date) as MAX_DATE FROM TABLE_2 where TABLE_2.REC_ID = TABLE_1.REC_ID and TABLE_2.NOTE_DATE &lt;= TABLE_1.REPORT_DATE ) NOTES_MAX_DATE from TABLE_1 where REC_ID = 121 order by TO_DATE(REPORT_DATE,'DD-MON-YY HH:MI:SS'); </code></pre> <p>Which should return the following:</p> <pre><code> REC_ID REPORT_DATE NOTES_MAX_DATE ---------------------- ------------------ ------------------------- 121 17-APR-10 12:30:00 121 24-APR-10 12:30:00 121 01-MAY-10 12:30:00 121 08-MAY-10 12:30:00 121 15-MAY-10 12:30:00 12-MAY-10 121 22-MAY-10 12:30:01 17-MAY-10 121 29-MAY-10 12:30:01 25-MAY-10 121 05-JUN-10 12:30:00 25-MAY-10 8 rows selected </code></pre> <p>The output needs to be the same as the above. I tried creating a join as follows:</p> <pre><code>SELECT TABLE_1.REC_ID, TO_CHAR(TABLE_1.REPORT_DATE,'DD-MON-YY HH:MI:SS') REPORT_DATE, MAX(TABLE_2.NOTE_DATE) AS NOTES_MAX_DATE FROM TABLE_2, TABLE_1 where TABLE_2.REC_ID = TABLE_1.REC_ID AND TABLE_2.NOTE_DATE &lt;= TABLE_1.REPORT_DATE and ( TABLE_1.SITE_ID = '1' ) and TABLE_1.REC_ID = 121 group by TABLE_1.REC_ID, TABLE_1.REPORT_DATE order by TO_DATE(REPORT_DATE,'DD-MON-YY HH:MI:SS'); </code></pre> <p>But that yields:</p> <pre><code> REC_ID REPORT_DATE NOTES_MAX_DATE ---------------------- ------------------ ------------------------- 121 15-MAY-10 12:30:00 12-MAY-10 121 22-MAY-10 12:30:01 17-MAY-10 121 29-MAY-10 12:30:01 25-MAY-10 121 05-JUN-10 12:30:00 25-MAY-10 </code></pre> <p>So I'm really stumped. Any ideas? -- Thanks.</p>
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