chore: add adbc, duckdb examples (#76)

Adds examples of running substrait plans with adbc (duckdb driver) and plain duckdb

Author: tokoko

examples/adbc_example.py

@@ -0,0 +1,44 @@
+# Install pyarrow, adbc-driver-manager and duckdb before running this example
+# This example  currently can be run only with duckdb<=1.1.3, later versions of duckdb no longer support substrait in adbc
+# /// script
+# dependencies = [
+#   "pyarrow==20.0.0",
+#   "adbc-driver-manager==1.5.0",
+#   "duckdb==1.1.3",
+#   "substrait[extensions] @ file:///${PROJECT_ROOT}/"
+# ]
+# ///
+
+
+import adbc_driver_duckdb.dbapi
+import pyarrow
+from substrait.builders.plan import read_named_table, filter
+from substrait.builders.extended_expression import scalar_function, column, literal
+from substrait.builders.type import i64
+from substrait.extension_registry import ExtensionRegistry
+import pyarrow.substrait as pa_substrait
+
+registry = ExtensionRegistry()
+
+data = pyarrow.record_batch(
+    [[1, 2, 3, 4], ["a", "b", "c", "d"]],
+    names=["ints", "strs"],
+)
+
+def read_adbc_named_table(name: str, conn):
+    pa_schema = conn.adbc_get_table_schema(name)
+    substrait_schema = pa_substrait.serialize_schema(pa_schema).to_pysubstrait().base_schema
+    return read_named_table(name, substrait_schema)
+
+with adbc_driver_duckdb.dbapi.connect(":memory:") as conn:
+    with conn.cursor() as cur:
+        cur.adbc_ingest("AnswerToEverything", data)
+
+        cur.executescript("INSTALL substrait;")
+        cur.executescript("LOAD substrait;")
+
+        table = read_adbc_named_table("AnswerToEverything", conn)
+        table = filter(table, expression=scalar_function('functions_comparison.yaml', 'gte', column('ints'), literal(3, i64())))
+
+        cur.execute(table(registry).SerializeToString())
+        print(cur.fetch_arrow_table())

examples/duckdb_example.py

@@ -0,0 +1,42 @@
+# Install duckdb and pyarrow before running this example
+# /// script
+# dependencies = [
+#   "pyarrow==20.0.0",
+#   "duckdb==1.2.1",
+#   "substrait[extensions] @ file:///${PROJECT_ROOT}/"
+# ]
+# ///
+
+
+import duckdb
+from substrait.builders.plan import read_named_table, project, filter
+from substrait.builders.extended_expression import column, scalar_function, literal
+from substrait.builders.type import i32
+from substrait.extension_registry import ExtensionRegistry
+from substrait.json import dump_json
+import pyarrow.substrait as pa_substrait
+
+try:
+    duckdb.install_extension("substrait")
+except:
+    duckdb.install_extension("substrait", repository="community")
+duckdb.load_extension("substrait")
+
+duckdb.install_extension("tpch")
+duckdb.load_extension("tpch")
+
+duckdb.sql("CALL dbgen(sf = 1);")
+
+registry = ExtensionRegistry(load_default_extensions=True)
+
+def read_duckdb_named_table(name: str, conn):
+    pa_schema = conn.sql(f"SELECT * FROM {name} LIMIT 0").arrow().schema
+    substrait_schema = pa_substrait.serialize_schema(pa_schema).to_pysubstrait().base_schema
+    return read_named_table(name, substrait_schema)
+
+table = read_duckdb_named_table("customer", duckdb)
+table = filter(table, expression=scalar_function('functions_comparison.yaml', 'equal', column('c_nationkey'), literal(3, i32())))
+table = project(table, expressions=[column('c_name'), column('c_address'), column('c_nationkey')])
+
+sql = f"CALL from_substrait_json('{dump_json(table(registry))}')"
+print(duckdb.sql(sql))