I test merge. However the merge will update the row regardless if there is update or not. I use Temporal table to verifiy this ----- all the mutch rows are tried as updated and create addtional new rows.
Even it may have some Teradata internal process to make update more effecitent during merge. However it can't tell which row(s) are really had update.
I wonder, is there is better solution within Teradata, not with thrid party tool?
If using hash, which hash is safe bet, or hash alway has risk regardless hash method?