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Thread: Spoon keeps opening db connections without asking

  1. #1
    Join Date
    Dec 2017

    Default Spoon keeps opening db connections without asking


    I have been working with pentaho for a while now and some behavior I noticed is: pentaho keeps opening connections with my database without me asking to run the transformation. It starts just because my transformation is opened on my spoon workspace.

    When the query in my transformation is lightweight it is no big deal, but sometimes I have some massive queries on it and if the execution is not planned it can overload my database.

    Do you guys noticed the same? Can I stop this behaviour?

  2. #2
    Join Date
    Aug 2016


    Yes I know why some connections are made. When you have an input step like Table Input, many subsequent steps will require to know which columns are generated by the sql query in order to display the available columns. This is default behavior and enables you to see options when selecting fields. However, these queries does not load any data, not sure exactly what these queries are, but I imagine they're something like 'select * from table_name limit 0'. The purpose is just to get the column names (and possibly type, int, string etc).

    What I have found is if you load the connection info (ip, password, user credentials, port) via a transformation (typically reading a config file) and write these to variables, Spoon can not send any queries to the database until you've run that transformation. This way you can enter the variables instead of hard-coding the db connection into the transformations. This method only works until you've run the transformation. After that, you would need to restart spoon to remove the variables.

    The queries sent by Spoon should not cause any overload however, so that is indeed strange. Can you log the queries and post them here?

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