InterviewSolution
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InterviewSolution
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Why Is Union All Faster Than Union? |
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Answer» The UNION operation removes redundancy while UNION ALL does not; therefore, the UNION operation needs to perform SORT. As a RESULT, UNION ALL PERFORMS better as it does not NEED to perform any sort. The UNION operation removes redundancy while UNION ALL does not; therefore, the UNION operation needs to perform sort. As a result, UNION ALL performs better as it does not need to perform any sort. |
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