Here you will learn "How to use Lookup data for Insert, Update and Delete by using tMap?" in Talend Open Studio.
We have an ideal business scenario where
business wants to ensure that lookup in output file, check if there is any
change in the new input file and if the record doesn't exists in the
output file, business needs to insert these records into the output file, if
the row already exists then they needs to update the data in the output file.
We have fields such as unique key such as SalespersonId and Salesyear in the both files. So, we will just use tMap with inner join with new file as main row and previous one as lookup.
Our source and target are raw data files and
using tFileInputDelimited, tFileOutputDelimited, tLogRow, tMap components in
the example.
If we need to detect deleted records, you need another
subjob where main row becomes the lookup, then rejected records are deleted
ones. All the records of the lookup flow need to be loaded before processing each record of the main flow.
Three types of lookup loading models are provided suiting various types of business requirement and the performance needs: Load once, Reload at each row, and Reload at each row (cache).
Used components to accomplished this jobs are -
tFileInputDelimated: We can use this component to read a file and
separate fields contained in this file using a defined separator. It allows you
to create a data flow.
tLogRow: This component is used
to monitor data processed and displays data or results in the Run console. This
component can be used as intermediate step in a data flow or as a n end object
in the Job flowchart.
tFileOutputDelimated: tFileOutputDelimited outputs data to
a delimited file and This component writes a delimited file that holds data
organized according to the defined schema. Use this component to write a
delimited file and separate fields using a field separator value.
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