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Thread: in which scene we should use "Append streams" step?

  1. #1
    Join Date
    May 2013
    Posts
    1

    Default in which scene we should use "Append streams" step?

    hello,i am a newer in kettle,and study hard.who can tell me,in which scene we should use "Append streams" step?

    3x very much

  2. #2
    Join Date
    Jun 2012
    Posts
    5,534

    Default

    If you read the description on the linked page and you don't see a use case for this step, have a look at the sample transformation.
    If you still don't see how this step can help you, just wait until a real world task is assigned to you, and try to remember this step when you need it.
    It's always better to look for a solution when having a problem and not the other way around.
    So long, and thanks for all the fish.

  3. #3
    Join Date
    Oct 2010
    Posts
    369

    Default

    use append stream when u want to append 2 data sources in ur transformaton e.g. if u have s1 and s2 as 2 data sources
    s1 having c1 as column which contain a b c as values
    s2 having c1 as column which contain d e f as values
    after using append stream u will get result set of a b c d e f

  4. #4
    Join Date
    Feb 2011
    Posts
    840

    Default

    lalgourav, I think you're mistaking Append streams with Merge Join. Append Streams must have 2 streams with the exactly same makeup (i.e: "Field1 - String", "Field2 - Number", etc... must be the same in both).

    And it APPENDS the streams, it doesn't merge s1+s2 into abcdef, as you mentioned.

    As the "IMPORTANT" says at the end of the wiki page...
    Important: If you don't care about the order in which the output rows occur, you can use any step to create a union of 2 or more data streams.
    From what I've seen, except for viewing pleasure, there's no real use for Append Stream step.
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