Обсуждение: Changing csv structure and corresponding etl

Hello,

I am using redshift to store data from csv backups that appear at a regular interval. I use pyspark (psycopg library)
toperform etl. The issue is that the csv structure changes in between and the etl job fails.  
The issue I found is that the column gets mixed up.
For example, the original column list was A,B,C,D. In the next iteration, the columns can be A, B, C, X,Y, D
I read from some of the other posts that it is not possible to alter a table to add a column in a particular position
withinPostgres.  
The table itself currently has millions of rows. Merging tables whenever I get a change may not be a good option. I.e.
createa union of existing table and new data, drop the original table and rename union to original. 
Any pointers in how to proceed?

Thanks,
Shekar
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