What happens?

Uniqueness in keys is not ensured by MAP function

To Reproduce

Steps to reproduce the behavior. Bonus points if those are only SQL queries.

Expected:

presto> select MAP(ARRAY[1, 1, 3, 4],ARRAY[10, 9, 8, 7]);
----
Query 20220513_121640_00001_hhhs4 failed: Duplicate map keys (1) are not allowed

Observed:

select MAP(LIST_VALUE(1, 1, 3, 4),LIST_VALUE(10, 9, 8, 7))
----
{1=10, 1=9, 3=8, 4=7}

Also NULL as a map key has this behavior on PrestoDB:

presto> select MAP(ARRAY[1, 1, 3, NULL],ARRAY[10, 9, 8, 7]);
----
Query 20220607_141513_00003_qpq6n failed: map key cannot be null

Arrow errors on this as well:

pyarrow.lib.ArrowInvalid: Invalid Map: key field can not contain null values

Environment (please complete the following information):

• OS: MacOS
• DuckDB Version: latest
• DuckDB Client: unittest

Before Submitting

• Have you tried this on the latest master branch?

• Python: pip install duckdb --upgrade --pre
• R: install.packages("https://github.com/duckdb/duckdb/releases/download/master-builds/duckdb_r_src.tar.gz", repos = NULL)
• Other Platforms: You can find binaries here or compile from source.

• Have you tried the steps to reproduce? Do they include all relevant data and configuration? Does the issue you report still appear there?