From bce011aab6530a543d1e21d75e5a45504b30feaa Mon Sep 17 00:00:00 2001 From: Guilherme Martins Crocetti <24530683+gmcrocetti@users.noreply.github.com> Date: Fri, 2 Aug 2024 15:40:37 -0300 Subject: [PATCH] feat: Implement option 'truncate' of argument 'if_exists' in 'DataFrame.to_sql' API. --- doc/source/whatsnew/v3.0.0.rst | 1 + pandas/io/sql.py | 66 ++++++++++++++++++++++++++++------ pandas/tests/io/test_sql.py | 60 +++++++++++++++++++++++++++++-- 3 files changed, 114 insertions(+), 13 deletions(-) diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst index da0d85b7bb529..1a19341f93265 100644 --- a/doc/source/whatsnew/v3.0.0.rst +++ b/doc/source/whatsnew/v3.0.0.rst @@ -59,6 +59,7 @@ Other enhancements - Support passing a :class:`Iterable[Hashable]` input to :meth:`DataFrame.drop_duplicates` (:issue:`59237`) - Support reading Stata 102-format (Stata 1) dta files (:issue:`58978`) - Support reading Stata 110-format (Stata 7) dta files (:issue:`47176`) +- Add ``"truncate"`` option to ``if_exists`` argument in :meth:`DataFrame.to_sql` truncating the table before inserting data (:issue:`37210`). .. --------------------------------------------------------------------------- .. _whatsnew_300.notable_bug_fixes: diff --git a/pandas/io/sql.py b/pandas/io/sql.py index 99dd06568fa01..c8501fac1452c 100644 --- a/pandas/io/sql.py +++ b/pandas/io/sql.py @@ -736,7 +736,7 @@ def to_sql( name: str, con, schema: str | None = None, - if_exists: Literal["fail", "replace", "append"] = "fail", + if_exists: Literal["fail", "replace", "append", "truncate"] = "fail", index: bool = True, index_label: IndexLabel | None = None, chunksize: int | None = None, @@ -762,10 +762,12 @@ def to_sql( schema : str, optional Name of SQL schema in database to write to (if database flavor supports this). If None, use default schema (default). - if_exists : {'fail', 'replace', 'append'}, default 'fail' + if_exists : {'fail', 'replace', 'append', 'truncate'}, default 'fail' - fail: If table exists, do nothing. - replace: If table exists, drop it, recreate it, and insert data. - append: If table exists, insert data. Create if does not exist. + - truncate: If table exists, truncate it. Create if does not exist. + Raises NotImplementedError if 'TRUNCATE TABLE' is not supported index : bool, default True Write DataFrame index as a column. index_label : str or sequence, optional @@ -816,7 +818,7 @@ def to_sql( `sqlite3 `__ or `SQLAlchemy `__ """ # noqa: E501 - if if_exists not in ("fail", "replace", "append"): + if if_exists not in ("fail", "replace", "append", "truncate"): raise ValueError(f"'{if_exists}' is not valid for if_exists") if isinstance(frame, Series): @@ -924,7 +926,7 @@ def __init__( pandas_sql_engine, frame=None, index: bool | str | list[str] | None = True, - if_exists: Literal["fail", "replace", "append"] = "fail", + if_exists: Literal["fail", "replace", "append", "truncate"] = "fail", prefix: str = "pandas", index_label=None, schema=None, @@ -972,11 +974,13 @@ def create(self) -> None: if self.exists(): if self.if_exists == "fail": raise ValueError(f"Table '{self.name}' already exists.") - if self.if_exists == "replace": + elif self.if_exists == "replace": self.pd_sql.drop_table(self.name, self.schema) self._execute_create() elif self.if_exists == "append": pass + elif self.if_exists == "truncate": + self.pd_sql.truncate_table(self.name, self.schema) else: raise ValueError(f"'{self.if_exists}' is not valid for if_exists") else: @@ -1468,7 +1472,7 @@ def to_sql( self, frame, name: str, - if_exists: Literal["fail", "replace", "append"] = "fail", + if_exists: Literal["fail", "replace", "append", "truncate"] = "fail", index: bool = True, index_label=None, schema=None, @@ -1854,7 +1858,7 @@ def prep_table( self, frame, name: str, - if_exists: Literal["fail", "replace", "append"] = "fail", + if_exists: Literal["fail", "replace", "append", "truncate"] = "fail", index: bool | str | list[str] | None = True, index_label=None, schema=None, @@ -1931,7 +1935,7 @@ def to_sql( self, frame, name: str, - if_exists: Literal["fail", "replace", "append"] = "fail", + if_exists: Literal["fail", "replace", "append", "truncate"] = "fail", index: bool = True, index_label=None, schema: str | None = None, @@ -1949,10 +1953,12 @@ def to_sql( frame : DataFrame name : string Name of SQL table. - if_exists : {'fail', 'replace', 'append'}, default 'fail' + if_exists : {'fail', 'replace', 'append', 'truncate'}, default 'fail' - fail: If table exists, do nothing. - replace: If table exists, drop it, recreate it, and insert data. - append: If table exists, insert data. Create if does not exist. + - truncate: If table exists, truncate it. Create if does not exist. + Raises NotImplementedError if 'TRUNCATE TABLE' is not supported index : boolean, default True Write DataFrame index as a column. index_label : string or sequence, default None @@ -2049,6 +2055,26 @@ def drop_table(self, table_name: str, schema: str | None = None) -> None: self.get_table(table_name, schema).drop(bind=self.con) self.meta.clear() + def truncate_table(self, table_name: str, schema: str | None = None) -> None: + from sqlalchemy.exc import OperationalError + + schema = schema or self.meta.schema + + if self.has_table(table_name, schema): + self.meta.reflect( + bind=self.con, only=[table_name], schema=schema, views=True + ) + with self.run_transaction(): + table = self.get_table(table_name, schema) + try: + self.execute(f"TRUNCATE TABLE {table.name}") + except OperationalError as exc: + raise NotImplementedError( + "'TRUNCATE TABLE' is not supported by this database." + ) from exc + + self.meta.clear() + def _create_sql_schema( self, frame: DataFrame, @@ -2306,7 +2332,7 @@ def to_sql( self, frame, name: str, - if_exists: Literal["fail", "replace", "append"] = "fail", + if_exists: Literal["fail", "replace", "append", "truncate"] = "fail", index: bool = True, index_label=None, schema: str | None = None, @@ -2328,6 +2354,8 @@ def to_sql( - fail: If table exists, do nothing. - replace: If table exists, drop it, recreate it, and insert data. - append: If table exists, insert data. Create if does not exist. + - truncate: If table exists, truncate it. Create if does not exist. + Raises NotImplementedError if 'TRUNCATE TABLE' is not supported index : boolean, default True Write DataFrame index as a column. index_label : string or sequence, default None @@ -2345,6 +2373,8 @@ def to_sql( engine : {'auto', 'sqlalchemy'}, default 'auto' Raises NotImplementedError if not set to 'auto' """ + from adbc_driver_manager import ProgrammingError + if index_label: raise NotImplementedError( "'index_label' is not implemented for ADBC drivers" @@ -2378,6 +2408,15 @@ def to_sql( cur.execute(f"DROP TABLE {table_name}") elif if_exists == "append": mode = "append" + elif if_exists == "truncate": + mode = "append" + with self.con.cursor() as cur: + try: + cur.execute(f"TRUNCATE TABLE {table_name}") + except ProgrammingError as exc: + raise NotImplementedError( + "'TRUNCATE TABLE' is not supported by this database." + ) from exc import pyarrow as pa @@ -2779,10 +2818,12 @@ def to_sql( frame: DataFrame name: string Name of SQL table. - if_exists: {'fail', 'replace', 'append'}, default 'fail' + if_exists: {'fail', 'replace', 'append', 'truncate'}, default 'fail' fail: If table exists, do nothing. replace: If table exists, drop it, recreate it, and insert data. append: If table exists, insert data. Create if it does not exist. + truncate: If table exists, truncate it. Create if does not exist. + Raises NotImplementedError if 'TRUNCATE TABLE' is not supported index : bool, default True Write DataFrame index as a column index_label : string or sequence, default None @@ -2858,6 +2899,9 @@ def drop_table(self, name: str, schema: str | None = None) -> None: drop_sql = f"DROP TABLE {_get_valid_sqlite_name(name)}" self.execute(drop_sql) + def truncate_table(self, name: str, schema: str | None = None) -> None: + raise NotImplementedError("'TRUNCATE TABLE' is not supported by this database.") + def _create_sql_schema( self, frame, diff --git a/pandas/tests/io/test_sql.py b/pandas/tests/io/test_sql.py index 980c88f070b89..62df4ec6d9735 100644 --- a/pandas/tests/io/test_sql.py +++ b/pandas/tests/io/test_sql.py @@ -1063,12 +1063,27 @@ def test_to_sql(conn, method, test_frame1, request): @pytest.mark.parametrize("conn", all_connectable) -@pytest.mark.parametrize("mode, num_row_coef", [("replace", 1), ("append", 2)]) +@pytest.mark.parametrize( + "mode, num_row_coef", [("replace", 1), ("append", 2), ("truncate", 1)] +) def test_to_sql_exist(conn, mode, num_row_coef, test_frame1, request): + connections_without_truncate = sqlite_connectable + [ + "sqlite_buildin", + "sqlite_adbc_conn", + ] + if conn in connections_without_truncate and mode == "truncate": + context = pytest.raises( + NotImplementedError, + match="'TRUNCATE TABLE' is not supported by this database.", + ) + else: + context = contextlib.nullcontext() conn = request.getfixturevalue(conn) + with pandasSQL_builder(conn, need_transaction=True) as pandasSQL: pandasSQL.to_sql(test_frame1, "test_frame", if_exists="fail") - pandasSQL.to_sql(test_frame1, "test_frame", if_exists=mode) + with context: + pandasSQL.to_sql(test_frame1, "test_frame", if_exists=mode) assert pandasSQL.has_table("test_frame") assert count_rows(conn, "test_frame") == num_row_coef * len(test_frame1) @@ -2693,6 +2708,47 @@ def test_drop_table(conn, request): assert not insp.has_table("temp_frame") +@pytest.mark.parametrize("conn", mysql_connectable + postgresql_connectable) +def test_truncate_table_success(conn, test_frame1, request): + table_name = "temp_frame" + conn = request.getfixturevalue(conn) + + with sql.SQLDatabase(conn) as pandasSQL: + with pandasSQL.run_transaction(): + assert pandasSQL.to_sql(test_frame1, table_name, if_exists="replace") == 4 + + with pandasSQL.run_transaction(): + pandasSQL.truncate_table(table_name) + assert count_rows(conn, table_name) == 0 + + +@pytest.mark.parametrize("conn", sqlite_connectable) +def test_truncate_table_not_supported(conn, test_frame1, request): + table_name = "temp_frame" + conn = request.getfixturevalue(conn) + + with sql.SQLDatabase(conn) as pandasSQL: + with pandasSQL.run_transaction(): + assert pandasSQL.to_sql(test_frame1, table_name, if_exists="replace") == 4 + + with pandasSQL.run_transaction(): + with pytest.raises( + NotImplementedError, + match="'TRUNCATE TABLE' is not supported by this database.", + ): + pandasSQL.truncate_table(table_name) + assert count_rows(conn, table_name) == len(test_frame1) + + +def test_truncate_table_sqlite_not_implemented(sqlite_buildin): + with sql.SQLiteDatabase(sqlite_buildin) as pandasSQL: + with pytest.raises( + NotImplementedError, + match="'TRUNCATE TABLE' is not supported by this database.", + ): + pandasSQL.truncate_table("table") + + @pytest.mark.parametrize("conn", all_connectable) def test_roundtrip(conn, request, test_frame1): if conn == "sqlite_str":