I am using the Data Flow(preview). My "Aggregate" activity requires a GroupBy column which is not dynamic. Hence, I cant group by that column. I just want to map the column by name.
For example:
These are the two schemas:
1) Columns: M Id, Date/Time, Data Type, Values
2) Columns: MID, Date, DataType, Units
Both have actually the same data type and structure. I want to GroupBy DataType and avg(units).
Because, the name of the one field is "Data Type" and other "DataType". How do I map it together.
I have created a "Derived" activity with this
Column: DataType
Expression: case(startsWith(toString(byPosition(7)), 'D'), toString(byName('Data Type')),toString(byName('DataType')))
But it doesnt work. Any help is highly appreciated.
I just want to know how do I map the column by name.
You can write a dynamic expression directly in the Group by field in the Aggregate transformation. Hover over the Group By field and select "Computed Column" to enter into the Expression Builder.
Are you trying to determine whether to use the column "Data Type" or the column called "DataType"? If so, just enter your conditional expression directly into the expression builder on the Aggregate group by. Note that in your expression above, you are using byPosition() which is a numeric value for the number representing the incoming columns left to right, starting at position 1. Is that what you intended?
Related
I have a very annoying problem when i try to merge two tables on power query excel. I use one column to match records from both tables and when i try to expand the second table it pops up the following message:
DataFormat.Error: We couldn't convert to Number.
Λεπτομέρειες:
ECS
I have no idea how to fix this. The columns that are matched have text, not value. There are no errors when i import data. Is there anyone that can help?
Try the following:
Delete the step #"Changed Type" in both queries
Make sure that the two merged columns have the same type (text ABC, in your case)
When you create a query from a table, Power Query try to guess (based on the first 200 lines) the type of each column. Now, the value "Λεπτομέρειες: ECS" is probably included in a different column (than the two merged) that has Number 123 as a type. It's kind of a mixed column (due to the source of data itself or to a delimiter issue).
I have a table with hundreds of columns.
This table will be modified in a pipeline on Datafactory.
One of these modifications is: change columns types from original type to desired type.
For example: the table have 50+ columns with type 'decimal' but i need to change them to 'integer'. All of this columns have a name starting with 'CD_'
How can i do that on Datafactory's Dataflow?
I'm trying to use Column Patterns in Derived Column Transformation. I created this following pattern (see picture attached).
My Column Pattern
But when i update the Data Visualization tab, i got the following error:
DF-EXPR-021 at Derive 'ChangeTypes'(Line 589/Col 30): Return types do not match
Thank you very much.
I wanted to implement SCD type 2 logic but using dynamic tables and dynamic key fields from Config Table, I have a challenge to pass the Data Flow Parameter as Sink Key Column for my Alter Row activity, it is not taking the parameter values and always gives the error as invalid key column name, I tried picking the Dataflow parameter for the expression builder at sink key column and trying to pass the value from alter row transformation and I have named the field with parameter in the select statement as well , any help or suggestion highly appreciated
Please clink below image
Sample How I wanted to Pass Dynamic Values in Sink Mapping
Trying to Give the Dynamic Value to Key Value
You have "List of columns" selected, so ADF is looking for a column in your target table that is literally called "$TargetPK1Parameter".
Change the selector to "Custom expression" and enter a string array parameter. The parameter can be an array of strings that represent names of key columns in your target table.
It should look something like this:
I encountered a similar problem when trying to pass a composite key, parameterized, as part of the update method to sink. This now allows me to fully parameterise my dataflow and it handles both composite keys and single columns keys.
Here's how the data looks in my config table:
UpsertKeyColumn = DOMNAME,DDLANGUAGE,AS4LOCAL,VALPOS,AS4VERS
A parameter value is set in the dataflow
Upsert_Key_Column = #item().UpsertKeyColumn
Finally, in the Sink settings, Custom Expression is selected for Key columns and the following expression is entered - split($upsert_key_column,',')
I'm having issues using the Exists Transformation within a Data Flow with a generic dataset.
I have two sources (one from staging table "sourceStg", one from DWH table "sourceDwh") and want to compare if the UniqueIdentifier-Column in the staging table is existing in the UniqueIdentifier-Column in the DWH table. For that I have a generic data set which I query with a SQL statement containing parameters.
When I open the "Exists settings" I cannot choose any Column from the source in the conditions since the source is generic and has no Projection until I run the data flow. However, I have a parameter which I get from the parent pipeline which provides me the name of the Column containing the UniqueIdentifier (both column names in staging / DWH are the same).
I tried to add following statement "byName($UniqueIdentifier)" in the left and right column field but the engine resolves them both as the sourceStg-Column since the prefix of the source-transformations is missing and it defaults to the first one. What I basically now try to achieve is having some statement as followed defining the correct source-transformation and the column containing the unique identifier with a parameter.
exists(sourceStg#$UniqueIdentifier == sourceDwh#$UniqueIdentifier)
But either the expression cannot be parsed or the result does not retrieve the actual UniqueIdentifier value from the column but writes the statement (e.g. sourceStg#$UniqueIdentifier) as column value.
The only workaround I found so far is having two derived columns which adds a suffix to the UniqueIdentifier-Column in one source and a new parameter $UniqueIdentiferDwh which is populate with the parameter $UniqueIdentifier and the same suffix as used in the derived column.
Any Azure Data Factory experts out there to help?
Thanks in advance!
I am trying to create a azure datafactory mapping dataflow that is generic for all tables. I am going to pass table name, the primary column for join purpose and other columns to be used in groupBy and aggregate functions as parameters to the DF.
parameters to df
I am unable to refernce this parameter in groupBy
Error: DF-AGG-003 - Groupby should reference atleast one column -
MapDrifted1 aggregate(
) ~> Aggregate1,[486 619]
Has anyone tried this scenario? Please help if you have some knowledge on this or if it can be handled in u-sql script.
We need to first lookup your parameter string name from your incoming source data to locate the metadata and assign it.
Just add a Derived Column previous to your Aggregate and it will work. Call the column 'groupbycol' in your Derived Column and use this formula: byName($group1).
In your Agg, select 'groupbycol' as your groupby column.