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Role of left input and right input in merge join

    Question

  • Hi All

    I really appreciate if someone explain me the difference between left input and right input in Merge Join.

    Sunday, March 23, 2014 11:11 AM

Answers

  • Think it in terms of transact sql join statement. The left input and right input represents the left and right part of join operation. So depending on type of operation chosen like LEFT JOIN,INNER JOIN etc it takes correspondig input as the base input and does join operation with the other input. Also it relies upon order of records in input which is why its essential that data should be sorted and also Issorted property must be tru for both the inputs.

    The real significance of choice is for left join as it will take left input as base table and does the comparison with other input returning all records from base input irrespective of whether or not it found a match. In all other cases (INNER/FULL JOIN) it gives similar output regardless of the which input you choose as left or right input.


    Please Mark This As Answer if it helps to solve the issue Visakh ---------------------------- http://visakhm.blogspot.com/ https://www.facebook.com/VmBlogs

    Sunday, March 23, 2014 6:38 PM

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