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Thread: Merge Join question

  1. #1
    Join Date
    Jan 2009
    Posts
    9

    Default Merge Join question

    I need to use merge join to join tables. after I click keys for 1st step and keys for 2nd step, there are key fields are listed on both sides. The question is how I join these two table since there is no way i can set up linking fields since i have different name for the linking fileds.

    BTW, there is warning saying the input need to be sorted on the specify fileds. does that mean I need to sort fileds in the input table?

    thanks
    welma

  2. #2
    Join Date
    Nov 1999
    Posts
    9,729

    Default

    Let the database do the join. That's what it was designed to do.

  3. #3

    Talking

    As for merge join step when i used it i didn't use sort step and it worked for my small tables.

  4. #4
    DEinspanjer Guest

    Default

    If you don't use a sort step, you are relying on the data coming through the streams to be in the correct order. If you are pulling the data from a sorted text file or a table with an order by clause, and the lexical ordering of that data exactly matches what the Java code in the Merge Join step uses, and you don't use any steps with multiple copies, and you don't have any filters that could drop or split rows, and you don't have any steps that could detect or generate an error on a row that would cause that row to be dropped then you would *probably* be okay. You get where I'm going with this, right?

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