[CT-2704] [Bug] When any of the unique keys is null incremental model duplicates data

[alejandrofm]

Is this a new bug in dbt-core?

• I believe this is a new bug in dbt-core
• I have searched the existing issues, and I could not find an existing issue for this bug

Current Behavior

When one or more unique keys have NULL values on the table, the incremental model appends a row instead of replacing the existing one.
So:
1, NULL, 1 duplicates the record
1, 2, 1 works ok

Expected Behavior

take null into account on unique keys of incremental models

Steps To Reproduce

set a unique key that could have NULL values.
run the incremental model twice

Relevant log output

No response

Environment

- OS: Ubuntu
- Python: 3.8
- dbt-core: 1.4

Which database adapter are you using with dbt?

No response

Additional Context

No response

[dbeatty10]

Thank you for reporting this @alejandrofm !

This looks like the same thing as dbt-labs/dbt-adapters#159, so I'm going to close this as a duplicate.