Refactor!: map duckdb LIST to ArrayAgg

[georgesittas]

This is Copilot's response when I asked whether LIST and ARRAY_AGG are synonymous in DuckDB:

«In DuckDB, list(expr) and array_agg(expr) are essentially the same kind of aggregate: both collect the grouped input values into a single LIST (array) value.

Practical differences are mostly about name/compatibility and a few option/details, not the core semantics:

• Purpose

  • array_agg is the more standard SQL / Postgres-style name.
  • list is a shorter DuckDB-friendly alias/name for the same idea.

• Return type

  • Both return DuckDB’s LIST type (conceptually an array).

• Options

  • Both typically support the same aggregate features you’d expect: DISTINCT, FILTER, and often ORDER BY within the aggregate (depending on DuckDB version).

So: yes, for normal usage they’re interchangeable—use array_agg if you want portability/readability for SQL folks, use list if you prefer the concise DuckDB idiom.

If you tell me your DuckDB version (or paste SELECT version();), I can be precise about any version-specific differences (e.g., ordering guarantees/availability of ORDER BY within the aggregate).»

Original PR: #7551

[georgesittas]

cc @maxa-jonathan-hallee

[georgesittas]

The advantage of this approach is that LIST is correctly identified as an AggFunc (because of ArrayAgg). The LIST function was added for Materializes' LIST function, which IIRC isn't an aggregate function. That's why I decided to change this.

[github-actions]

SQLGlot Integration Test Results

Comparing:

• this branch (sqlglot:jo/map_ddb_list_to_array_agg, sqlglot version: jo/map_ddb_list_to_array_agg)
• baseline (main, sqlglot version: 0.0.1.dev1)

By Dialect

dialect	main	sqlglot:jo/map_ddb_list_to_array_agg	transitions	links
bigquery -> bigquery	24645/24650 passed (100.0%)	23495/23495 passed (100.0%)	No change	full result / delta
bigquery -> duckdb	867/1154 passed (75.1%)	0/0 passed (0.0%)	Results not found	full result / delta
duckdb -> duckdb	5823/5823 passed (100.0%)	5823/5823 passed (100.0%)	No change	full result / delta
snowflake -> duckdb	1063/1961 passed (54.2%)	1063/1961 passed (54.2%)	No change	full result / delta
snowflake -> snowflake	65133/65133 passed (100.0%)	65133/65133 passed (100.0%)	No change	full result / delta
databricks -> databricks	1370/1370 passed (100.0%)	1370/1370 passed (100.0%)	No change	full result / delta
postgres -> postgres	6042/6042 passed (100.0%)	6042/6042 passed (100.0%)	No change	full result / delta
redshift -> redshift	7101/7101 passed (100.0%)	7101/7101 passed (100.0%)	No change	full result / delta

Overall

main: 113234 total, 112044 passed (pass rate: 98.9%), sqlglot version: 0.0.1.dev1

sqlglot:jo/map_ddb_list_to_array_agg: 110925 total, 110027 passed (pass rate: 99.2%), sqlglot version: jo/map_ddb_list_to_array_agg

Transitions:
No change

Dialect pair changes: 0 previous results not found, 1 current results not found

✅ 34 test(s) passed