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jcountryman's avatar
jcountryman
Helper I
7 years ago

Need advice working with multiple Nested Joins

Have several tables that need Joining to a single 'master'. Assuming there are no steps between each join, what is the best practice?

 

  1. Repeated Table.NestedJoin(), then a series of Table.ExpandTableColumn() operations? 
  2. Or several steps of Table.ExpandTableColumn(Table.NestedJoin())?
Need Help

2 Replies

    • jcountryman's avatar
      jcountryman
      Helper I
      7 years ago

      Thank you, but that doesn't quite address my question. Which is more efficient?

      1. #"Step1" = Table.NestedJoin(MASTER,{"UID"},TABLE_1,{"UID"},"SUB_TABLE_1"),
#"Step2" = Table.NestedJoin(#"Step1",{"UID"},TABLE_2,{"UID"},"SUB_TABLE_2"),
#"Step3" = Table.NestedJoin(#"Step2",{"UID"},TABLE_3,{"UID"},"SUB_TABLE_3"),
#"Step4" = Table.ExpandTableColumn(#"Step3","SUB_TABLE_1",{"Col2","Col3"}),
#"Step5" = Table.ExpandTableColumn(#"Step4","SUB_TABLE_2",{"Col4","Col5"}),
#"Step6" = Table.ExpandTableColumn(#"Step5","SUB_TABLE_3",{"Col6","Col7"})

         

      2. #"Step1" = Table.ExpandTableColumn(
                Table.NestedJoin(MASTER,{"UID"},TABLE_1,{"UID"},"SUB_TABLE_1"),
                "SUB_TABLE_1",
                {"Col2","Col3"}
            ),
#"Step2" = Table.ExpandTableColumn(
                Table.NestedJoin(#"Step1",{"UID"},TABLE_2,{"UID"},"SUB_TABLE_2"),
                "SUB_TABLE_2",
                {"Col4","Col5"}
            ),
#"Step3" = Table.ExpandTableColumn(
                Table.NestedJoin(#"Step2",{"UID"},TABLE_3,{"UID"},"SUB_TABLE_3"),
                "SUB_TABLE_3",
                {"Col6","Col7"}
            )