how to write usql query to output to multiple files - azure-data-lake

Question

i want to group data set based on unique values in column and save them to multiple file.
My problem is same as which is already described here at link:
U-SQL Output in Azure Data Lake
As i am new to USQL language , i am unable to implement the second step from answer. I am unable to figure out how to write usql query to run generated usql script from the first part of answer

Answer 1

If the number of groups is known in advance, you could write a USQL stored procedure that would take as parameter 1) the value of the group 2) the name of the file.
In the pseudo-code below, the name of the final file is driven by the underlying value of the group. The data to be split is sourced from a USQL table (referred in the pseudo-code as ).
DROP PROCEDURE IF EXISTS splitByGroups;
CREATE PROCEDURE splitByGroups(#groupValue string, #file_name_prefix string = "extract")
AS
BEGIN
DECLARE #OUTPUT string = "/output/" + file_name_prefix + "_"+ #groupValue + ".csv";
OUTPUT (
SELECT *
FROM <MyTable>
WHERE <MyGroup> == #groupValue
)
TO #OUTPUT
USING Outputters.Csv(outputHeader : true);
END;
You would then execute the stored procedure as many times as you have groups:
splitByGroups("group1", DEFAULT);
splitByGroups("group1", DEFAULT);
Alternatively, if you wish to analyse the multiple files offline, I would download the full file and use the shell (PowerShell or Linux Shell) to split the file.