Warn / fail if contents of delta files have changed

[volcan01010]

I have enjoyed experimenting the PUM this afternoon. It looks very useful. Thank you for creating it.

I tried the following:

• Create delta_0.0.201807131730.sql that does CREATE TABLE IF NOT EXISTS public.test
• Apply delta with pum upgrade. Result is success.
• Modify delta file to add another column to table.
• pum info reports delta file as pending but applied upgrades for same file as success.
• pum upgrade applies delta and reports success.
• Extra column is not added to table (due to IF NOT EXISTS)

I expected pum to report that the checksum for the delta file was different from the one recorded in the metadata and prevent me from applying the upgrade. That is what DBFit does. It is a very useful feature. Would it be possible to implement this?