Support duckdbpyrelation as input type

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- When using DuckDB, you can now pass `duckdb.DuckDBPyRelation`s as input tables to the `Linker` ([#2375](https://github.com/moj-analytical-services/splink/pull/2375))
+
 ### Fixed
 
 - Completeness chart now works correctly with indexed columns in spark ([#2309](https://github.com/moj-analytical-services/splink/pull/2309))

splink/internals/athena/database_api.py

@@ -3,13 +3,13 @@
 import json
 import logging
 import os
-from typing import Any, Sequence
+from typing import Any
 
 import awswrangler as wr
 import boto3
 import pandas as pd
 
-from ..database_api import AcceptableInputTableType, DatabaseAPI
+from ..database_api import DatabaseAPI
 from ..dialects import AthenaDialect
 from ..sql_transform import sqlglot_transform_sql
 from .athena_helpers.athena_transforms import cast_concat_as_varchar
@@ -250,17 +250,3 @@ def accepted_df_dtypes(self):
         except ImportError:
             pass
         return accepted_df_dtypes
-
-    def load_from_file(self, file_path: str) -> str:
-        raise NotImplementedError(
-            "Loading from file is not supported for Athena. "
-            "Please use the `table` method to load data."
-        )
-
-    def process_input_tables(
-        self, input_tables: Sequence[AcceptableInputTableType]
-    ) -> Sequence[AcceptableInputTableType]:
-        input_tables = super().process_input_tables(input_tables)
-        return [
-            self.load_from_file(t) if isinstance(t, str) else t for t in input_tables
-        ]

splink/internals/duckdb/database_api.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 import logging
-from typing import Sequence, Union
+from typing import Union
 
 import duckdb
 import pandas as pd
@@ -14,7 +14,6 @@
 from .dataframe import DuckDBDataFrame
 from .duckdb_helpers.duckdb_helpers import (
     create_temporary_duckdb_connection,
-    duckdb_load_from_file,
     validate_duckdb_connection,
 )
 
@@ -93,9 +92,6 @@ def table_exists_in_database(self, table_name):
             return False
         return True
 
-    def load_from_file(self, file_path: str) -> str:
-        return duckdb_load_from_file(file_path)
-
     def _execute_sql_against_backend(self, final_sql: str) -> duckdb.DuckDBPyRelation:
         return self._con.sql(final_sql)
 
@@ -110,11 +106,3 @@ def accepted_df_dtypes(self):
         except ImportError:
             pass
         return accepted_df_dtypes
-
-    def process_input_tables(
-        self, input_tables: Sequence[AcceptableInputTableType]
-    ) -> Sequence[AcceptableInputTableType]:
-        input_tables = super().process_input_tables(input_tables)
-        return [
-            self.load_from_file(t) if isinstance(t, str) else t for t in input_tables
-        ]

splink/internals/duckdb/dataframe.py

@@ -4,6 +4,7 @@
 import os
 from typing import TYPE_CHECKING
 
+from duckdb import DuckDBPyRelation
 from pandas import DataFrame as pd_DataFrame
 
 from splink.internals.input_column import InputColumn
@@ -50,6 +51,13 @@ def as_pandas_dataframe(self, limit: int = None) -> pd_DataFrame:
 
         return self.db_api._execute_sql_against_backend(sql).to_df()
 
+    def as_duckdbpyrelation(self, limit: int = None) -> DuckDBPyRelation:
+        sql = f"select * from {self.physical_name}"
+        if limit:
+            sql += f" limit {limit}"
+
+        return self.db_api._execute_sql_against_backend(sql)
+
     def to_parquet(self, filepath, overwrite=False):
         if not overwrite:
             self.check_file_exists(filepath)

splink/internals/duckdb/duckdb_helpers/duckdb_helpers.py

@@ -1,7 +1,6 @@
 import os
 import tempfile
 import uuid
-from pathlib import Path
 
 import duckdb
 
@@ -26,7 +25,7 @@ def validate_duckdb_connection(connection, logger):
 
     connection = connection.lower()
 
-    if connection in [":memory:", ":temporary:"]:
+    if connection in [":memory:", ":temporary:", ":default:"]:
         return
 
     suffixes = (".duckdb", ".db")
@@ -49,15 +48,3 @@ def create_temporary_duckdb_connection(self):
     path = os.path.join(self._temp_dir.name, f"{fname}.duckdb")
     con = duckdb.connect(database=path, read_only=False)
     return con
-
-
-def duckdb_load_from_file(path: str) -> str:
-    file_functions = {
-        ".csv": f"read_csv_auto('{path}')",
-        ".parquet": f"read_parquet('{path}')",
-    }
-    file_ext = Path(path).suffix
-    if file_ext in file_functions.keys():
-        return file_functions[file_ext]
-    else:
-        return path

splink/internals/linker.py

@@ -306,9 +306,11 @@ def _register_input_tables(
         input_tables: Sequence[AcceptableInputTableType],
         input_aliases: Optional[str | List[str]],
     ) -> Dict[str, SplinkDataFrame]:
+        input_tables_list = ensure_is_list(input_tables)
+
         if input_aliases is None:
             input_table_aliases = [
-                f"__splink__input_table_{i}" for i, _ in enumerate(input_tables)
+                f"__splink__input_table_{i}" for i, _ in enumerate(input_tables_list)
             ]
             overwrite = True
         else:

tests/test_full_example_duckdb.py

@@ -1,5 +1,6 @@
 import os
 
+import duckdb
 import pandas as pd
 import pyarrow as pa
 import pyarrow.csv as pa_csv
@@ -8,10 +9,9 @@
 
 import splink.internals.comparison_level_library as cll
 import splink.internals.comparison_library as cl
+from splink import DuckDBAPI, Linker, SettingsCreator, block_on
 from splink.blocking_analysis import count_comparisons_from_blocking_rule
 from splink.exploratory import completeness_chart, profile_columns
-from splink.internals.duckdb.database_api import DuckDBAPI
-from splink.internals.linker import Linker
 
 from .basic_settings import get_settings_dict, name_comparison
 from .decorator import mark_with_dialects_including
@@ -197,10 +197,6 @@ def test_link_only(input, source_l, source_r):
             pd.read_csv("./tests/datasets/fake_1000_from_splink_demos.csv"),
             id="DuckDB link from pandas df",
         ),
-        pytest.param(
-            "./tests/datasets/fake_1000_from_splink_demos.csv",
-            id="DuckDB load from file",
-        ),
         pytest.param(
             pa.Table.from_pandas(
                 pd.read_csv("./tests/datasets/fake_1000_from_splink_demos.csv")
@@ -219,7 +215,7 @@ def test_link_only(input, source_l, source_r):
     ],
 )
 @mark_with_dialects_including("duckdb")
-def test_duckdb_load_from_file(df):
+def test_duckdb_load_different_tablish_types(df):
     settings = get_settings_dict()
 
     db_api = DuckDBAPI()
@@ -324,3 +320,18 @@ def test_small_example_duckdb(tmp_path):
     linker.training.estimate_parameters_using_expectation_maximisation(blocking_rule)
 
     linker.inference.predict()
+
+
+@mark_with_dialects_including("duckdb")
+def test_duckdb_input_is_duckdbpyrelation():
+    df1 = duckdb.read_csv("./tests/datasets/fake_1000_from_splink_demos.csv")
+    df2 = pd.read_csv("./tests/datasets/fake_1000_from_splink_demos.csv")
+
+    settings = SettingsCreator(
+        link_type="link_and_dedupe",
+        comparisons=[cl.ExactMatch("first_name")],
+        blocking_rules_to_generate_predictions=[block_on("first_name", "surname")],
+    )
+    db_api = DuckDBAPI(connection=":default:")
+    linker = Linker([df1, df2], settings, db_api)
+    linker.inference.predict()