feat(duckdb): add dict-like for DuckDB settings

Adds a dict-like passthrough object for setting options in the DuckDB
backend.

The repr will show all values as stringified, but this is also how
they'll be passed in.

This avoids users having to pass in options via calls to `raw_sql` or similar.

Co-authored-by: Phillip Cloud <417981+cpcloud@users.noreply.github.com>

ibis/backends/duckdb/__init__.py

@@ -7,10 +7,7 @@
 import os
 import warnings
 from pathlib import Path
-from typing import (
-    TYPE_CHECKING,
-    Any,
-)
+from typing import TYPE_CHECKING, Any
 
 import duckdb
 import pyarrow as pa
@@ -69,11 +66,41 @@ def _format_kwargs(kwargs: Mapping[str, Any]):
 }
 
 
+class _Settings:
+    def __init__(self, con):
+        self.con = con
+
+    def __getitem__(self, key):
+        try:
+            with self.con.begin() as con:
+                return con.exec_driver_sql(
+                    f"select value from duckdb_settings() where name = '{key}'"
+                ).one()
+        except sa.exc.NoResultFound:
+            raise KeyError(key)
+
+    def __setitem__(self, key, value):
+        with self.con.begin() as con:
+            con.exec_driver_sql(f"SET {key}='{value}'")
+
+    def __repr__(self):
+        with self.con.begin() as con:
+            kv = con.exec_driver_sql(
+                "select map(array_agg(name), array_agg(value)) from duckdb_settings()"
+            ).scalar()
+
+        return repr(dict(zip(kv["key"], kv["value"])))
+
+
 class Backend(AlchemyCrossSchemaBackend, CanCreateSchema):
     name = "duckdb"
     compiler = DuckDBSQLCompiler
     supports_create_or_replace = True
 
+    @property
+    def settings(self) -> _Settings:
+        return _Settings(self)
+
     @property
     def current_database(self) -> str:
         return self._scalar_query(sa.select(sa.func.current_database()))

ibis/backends/duckdb/tests/test_client.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import duckdb
+import pyarrow as pa
 import pytest
 import sqlalchemy as sa
 from pytest import param
@@ -132,3 +133,28 @@ def test_create_table_with_timestamp_scales(con, scale):
     schema = ibis.schema(dict(ts=dt.Timestamp(scale=scale)))
     t = con.create_table(gen_name("duckdb_timestamp_scale"), schema=schema, temp=True)
     assert t.schema() == schema
+
+
+def test_config_options(con):
+    a_first = {"a": [None, 1]}
+    a_last = {"a": [1, None]}
+    nulls_first = pa.Table.from_pydict(a_first, schema=pa.schema([("a", pa.float64())]))
+    nulls_last = pa.Table.from_pydict(a_last, schema=pa.schema([("a", pa.float64())]))
+
+    t = ibis.memtable(a_last)
+
+    expr = t.order_by("a")
+
+    assert con.to_pyarrow(expr) == nulls_last
+
+    con.settings["null_order"] = "nulls_first"
+
+    assert con.to_pyarrow(expr) == nulls_first
+
+
+def test_config_options_bad_option(con):
+    with pytest.raises(sa.exc.ProgrammingError):
+        con.settings["not_a_valid_option"] = "oopsie"
+
+    with pytest.raises(KeyError):
+        con.settings["i_didnt_set_this"]