Need advice working with multiple Nested Joins

[jcountryman]

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())?

[v-danhe-msft]

Hi @jcountryman ,

Based on my test, you may use the second way to deal with your data and refer to blow issue:

https://community.powerbi.com/t5/Desktop/Merging-a-single-table-to-multiple-tables-at-once/td-p/4494...

Regards,

Daniel He

[jcountryman]

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"}
       )