Multiple choice technology web technology

Name the operation which UNION ALL skips when compared to UNION?

  1. HASH JOIN

  2. SORT UNIQUE

  3. TABLE FULL ACCESS

  4. INDEX RANGE SCAN
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B Correct answer
Explanation

UNION performs a SORT UNIQUE operation to eliminate duplicate rows from the combined result set, which requires sorting. UNION ALL skips this sorting and deduplication step, simply concatenating all rows from both queries. This makes UNION ALL faster when you don't need to remove duplicates.

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