What are the Import File Merge Modes

Import File Merge Modes

The merge modes work before any of the data is actually imported. The match mode attempts to find existing data in the system first, and based on whether it finds 0 matches or 1 match, the merge mode determines what happens next (more than 1 match results in the row erroring):

InsertOnly:

if the match mode found 0 matches, import the data. Otherwise (1 match), skip

UpdateOnly:

if the match mode found 1 match, update that matched data. Otherwise (0 matches), the row errors

Upsert:

if the match mode found 0 matches, import the data. Otherwise (1 match), update the matched data. This works well as a default since it does both inserts and updates (upsert is a combination of the words update and insert)

After that point, we know we are importing the current row of data, so the import service goes column by column and imports each cell on that row from the import file. As it goes column by column, that’s when the field rules get applied.