| How To Eliminate Sort Unique [message #416194] |
Fri, 31 July 2009 02:13  |
vinniora
Messages: 56
Registered: October 2008
Location: Mumbai
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Member |
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Hi all, I Have fired a query
SELECT DISTINCT B.BDECOILID cc FROM COILS B, DEFECTS A WHERE B.COILID=A.COILID
it's explain plan is showing sort unique and it's cost 845k
| Id |Operation | Name| Rows | Bytes |TempSpc| Cost (%CPU)|
| 0 | SELECT STATEMENT | | 10142 | 217K||845K (54)|
| 1 | SORT UNIQUE | | 10142 | 217K| 185M|845K (54)
| 2 |NESTED LOOPS | | 6882K| 144M|| 45348 (29)|
| 3 |TABLE ACCESS FULL| COILS | 10711 | 177K| 217 (50)|
|*4 |INDEX RANGE SCAN | COIL_ID_DEFECTS | 643 | 3215 |4 (25)|
It is too much time because of distinct keyword is their any way to reduce the cost.
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| Re: How To Eliminate Sort Unique [message #416403 is a reply to message #416194] |
Sat, 01 August 2009 10:37  |
amardeep.sidhu
Messages: 7
Registered: October 2007
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Junior Member |
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As you are asking it to return DISTINCT values so it goes for sort unique. If you are sure that there would be no duplicates then you can get rid of DISTINCT and consequently SORT UNIQUE.
Regards,
Amardeep Sidhu
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