A few case studies and discussed the previous work experience

All scenario based questions , none straight. 1) In what situations can middleware tool fail to transfer all table columns from source ( oracle) to target ( Snowflake) 2) SQL coding questions involving join on 2 tables and aggregate results like max / avg 3) Files getting loaded daily to SF stage. One day if external interface fails to deliver files that were to be loaded , what could possibly go wrong ? 4) how to find duplicate files/records in SF.