Replace Mode
Database and Application Sources
Pipelines in Replace mode extract the entire contents of the source during every extraction. When the transformed records are loaded, all the existing records are removed from the destination table.
This mode is used in cases where the source doesn’t allow querying for changed data. For database sources, this mode is used when a table doesn’t have a primary key.

File Sources
Each file is assumed to contain the full contents of the source. When the transformed records are loaded, all the existing records are removed from the destination table. When you create a new replace-mode pipeline from a folder, only the file with the latest modification time in that folder is processed.