Merge pull request #105942 from kromerm/dataflow-1

Dataflow 1

Author: PRMerger18

articles/data-factory/data-flow-flatten.md

@@ -1,6 +1,6 @@
 ---
 title: Mapping data flow flatten transformation
-description: Azure data factory mapping data flow flatten transformation
+description: Azure Data Factory Mapping Data Flow flatten transformation
 author: kromerm
 ms.author: makromer
 ms.service: data-factory
@@ -24,7 +24,7 @@ First, choose the array column that you wish to unroll and pivot.
 
 ## Unroll root
 
-By default ADF will flatten the structure at the unroll array that you chose above. Or, you can choose a different part of the hierarchy to unroll to.
+By default ADF will flatten the structure at the unroll array that you chose above. Or, you can choose a different part of the hierarchy to unroll to. "Unroll root" is an optional setting.
 
 ## Input columns
 

articles/data-factory/data-flow-lookup.md

@@ -41,6 +41,9 @@ The Lookup Transformation is implemented as a left outer join. When you have mul
 * Match on: Select first, last, or any match
 * Sort conditions: If you select first or last, ADF requires your data to be ordered so that there is logic behind first and last
 
+> [!NOTE]
+> Only use the first or last option on your single row selector if you need to control which value to bring back from your lookup. Using "any" or multi-row lookups will perform faster.
+
 ### Option 2
 
 You can also do this using an Aggregate transformation after your Lookup. In this case, an Aggregate transformation called ```PickFirst``` is used to pick the first value from the lookup matches.