ErrorCode=InvalidParameter,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=The value of the property 'columns' is invalid: 'Value cannot be null. Parameter name: columns'.,Source=,''Type=System.ArgumentNullException,Message=Valu

Question

Hi,

Am new to Postgresql, am trying to fetch the column list and their respective data types for a Postgresql table using a lookup activity within a foreach container in ADF . Query is working fine and fetching the expected output when executed in Azure Data Studio. however it is failing with the error in ADF.

ErrorCode=InvalidParameter,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=The value of the property 'columns' is invalid: 'Value cannot be null.

Parameter name: columns'.,Source=,''Type=System.ArgumentNullException,Message=Value cannot be null.

Parameter name: columns,Source=Microsoft.DataTransfer.Common,'

Following is the query used in Lookup activity.

DO $$ 
DECLARE 
    ColList TEXT := ''; 
    DataTypeList TEXT := ''; 
    col_sep TEXT := '@{pipeline().parameters.ColumnSeparator}'; 
    tablename TEXT := '@{item().table}'; 
    schemaname TEXT := '@{item().schema}'; 
BEGIN 
    SELECT 
        STRING_AGG('"' || column_name || '"', col_sep) AS ColList,
        STRING_AGG(data_type, col_sep) AS DataTypeList
    INTO ColList, DataTypeList
    FROM information_schema.columns 
    WHERE table_name = tablename 
    AND table_schema = schemaname;

    RAISE NOTICE '%', ColList;
    RAISE NOTICE '%', DataTypeList; 
END $$;

Answer 1

@TUMMALAPELLY, Sandeep

It looks like the issue is occurring because the ADF Lookup activity expects a tabular result, but your current query does not return a result set. Instead, it assigns values to variables and uses RAISE NOTICE, which does not return data in a format that ADF can process.

Why Does This Query Fail in ADF?

ADF Lookup Activity Expecting a Table Format - ADF Lookup expects a tabular result (rows and columns), but this query does not return a result set. Instead, it stores results in variables (ColList, DataTypeList) and prints them using RAISE NOTICE, which is not useful in ADF.

Solution: Use a SELECT Statement Instead of RAISE NOTICE

Replace:

RAISE NOTICE '%', ColList;
RAISE NOTICE '%', DataTypeList;

With:

SELECT ColList AS column_names, DataTypeList AS data_types;

This way, ADF Lookup will receive a proper table format like:

• column_names - "id","name","age"
• data_types - integer,text,integer

Why This Fix Works?

Instead of just printing values, this query returns a table format (column_names and data_types). ADF Lookup activity can now capture and process the output correctly.

I hope this information helps. Please do let us know if you have any further queries.

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