refactor(api): remove now unsupported max_lookback window attribute

This feature was only supported by the pandas backend, but wasn\'t tested
properly and the support for it was entirely removed in the-epic-split refactor.

BREAKING CHANGE: `ibis.rows_with_max_lookback()` function and `ibis.window(max_lookback)` argument are removed

ibis/backends/impala/tests/test_window.py

@@ -63,15 +63,6 @@ def test_window_frame_specs(alltypes, window, snapshot):
     assert_sql_equal(expr, snapshot)
 
 
-def test_window_rows_with_max_lookback(alltypes):
-    mlb = ibis.rows_with_max_lookback(3, ibis.interval(days=3))
-    t = alltypes
-    w = ibis.trailing_window(mlb, order_by=t.i)
-    expr = t.a.sum().over(w)
-    with pytest.raises(NotImplementedError):
-        ibis.to_sql(expr, dialect="impala")
-
-
 @pytest.mark.parametrize("name", ["sum", "min", "max", "mean"])
 def test_cumulative_functions(alltypes, name, snapshot):
     t = alltypes

ibis/backends/pandas/tests/test_window.py

@@ -7,13 +7,11 @@
 import numpy as np
 import pandas as pd
 import pytest
-from packaging.version import parse as vparse
 
 import ibis
 import ibis.expr.datatypes as dt
 from ibis.backends.pandas import Backend
 from ibis.backends.pandas.tests.conftest import TestConf as tm
-from ibis.common.annotations import ValidationError
 from ibis.legacy.udf.vectorized import reduction
 
 
@@ -469,48 +467,6 @@ def test_window_with_preceding_expr(index):
     tm.assert_series_equal(result, expected.rename("mean"))
 
 
-@pytest.mark.xfail(
-    condition=vparse("1.4") <= vparse(pd.__version__) < vparse("1.4.2"),
-    raises=ValueError,
-    reason="https://github.com/pandas-dev/pandas/pull/44068",
-)
-def test_window_with_mlb():
-    index = pd.date_range("20170501", "20170507")
-    data = np.random.randn(len(index), 3)
-    df = (
-        pd.DataFrame(data, columns=list("abc"), index=index)
-        .rename_axis("time")
-        .reset_index(drop=False)
-    )
-    client = ibis.pandas.connect({"df": df})
-    t = client.table("df")
-    rows_with_mlb = ibis.rows_with_max_lookback(5, ibis.interval(days=10))
-    expr = t.mutate(
-        sum=lambda df: df.a.sum().over(
-            ibis.trailing_window(rows_with_mlb, order_by="time", group_by="b")
-        )
-    )
-    result = expr.execute()
-    expected = df.set_index("time")
-    gb_df = (
-        expected.groupby(["b"])["a"]
-        .rolling("10d", closed="both")
-        .apply(lambda s: s.iloc[-5:].sum(), raw=False)
-        .sort_index(level=["time"])
-        .reset_index(drop=True)
-    )
-    expected = expected.reset_index(drop=False).assign(sum=gb_df)
-    tm.assert_frame_equal(result, expected)
-
-    rows_with_mlb = ibis.rows_with_max_lookback(5, 10)
-    with pytest.raises(ValidationError):
-        t.mutate(
-            sum=lambda df: df.a.sum().over(
-                ibis.trailing_window(rows_with_mlb, order_by="time")
-            )
-        )
-
-
 def test_window_grouping_key_has_scope(t, df):
     param = ibis.param(dt.string)
     window = ibis.window(group_by=t.dup_strings + param)

ibis/backends/postgres/tests/test_functions.py

@@ -712,17 +712,6 @@ def test_rolling_window(alltypes, func, df):
     tm.assert_series_equal(result, expected)
 
 
-def test_rolling_window_with_mlb(alltypes):
-    t = alltypes
-    window = ibis.trailing_window(
-        preceding=ibis.rows_with_max_lookback(3, ibis.interval(days=5)),
-        order_by=t.timestamp_col,
-    )
-    expr = t["double_col"].sum().over(window)
-    with pytest.raises(NotImplementedError):
-        expr.execute()
-
-
 @pytest.mark.parametrize("func", ["mean", "sum", "min", "max"])
 def test_partitioned_window(alltypes, func, df):
     t = alltypes

ibis/backends/risingwave/tests/test_functions.py

@@ -506,17 +506,6 @@ def test_rolling_window(alltypes, func, df):
     tm.assert_series_equal(result, expected)
 
 
-def test_rolling_window_with_mlb(alltypes):
-    t = alltypes
-    window = ibis.trailing_window(
-        preceding=ibis.rows_with_max_lookback(3, ibis.interval(days=5)),
-        order_by=t.timestamp_col,
-    )
-    expr = t["double_col"].sum().over(window)
-    with pytest.raises(NotImplementedError):
-        expr.execute()
-
-
 @pytest.mark.parametrize("func", ["mean", "sum", "min", "max"])
 @pytest.mark.xfail(
     reason="Window function with empty PARTITION BY is not supported yet"

ibis/backends/sql/rewrites.py

@@ -102,8 +102,6 @@ def sort_to_select(_, **kwargs):
 @replace(p.WindowFunction)
 def window_function_to_window(_, **kwargs):
     """Convert a WindowFunction node to a Window node."""
-    if isinstance(_.frame, ops.RowsWindowFrame) and _.frame.max_lookback is not None:
-        raise NotImplementedError("max_lookback is not supported for SQL backends")
     return Window(
         how=_.frame.how,
         func=_.func,

ibis/expr/api.py

@@ -9,7 +9,7 @@
 import numbers
 import operator
 from collections import Counter
-from typing import TYPE_CHECKING, Any, NamedTuple, overload
+from typing import TYPE_CHECKING, Any, overload
 
 import ibis.expr.builders as bl
 import ibis.expr.datatypes as dt
@@ -44,7 +44,6 @@
     from collections.abc import Iterable, Sequence
     from pathlib import Path
 
-    import numpy as np
     import pandas as pd
     import pyarrow as pa
 
@@ -154,7 +153,6 @@
     "read_parquet",
     "row_number",
     "rows_window",
-    "rows_with_max_lookback",
     "schema",
     "Schema",
     "selectors",
@@ -1591,32 +1589,6 @@ def get_backend(expr: Expr | None = None) -> BaseBackend:
     return expr._find_backend(use_default=True)
 
 
-class RowsWithMaxLookback(NamedTuple):
-    rows: int
-    max_lookback: ir.IntervalValue
-
-
-def rows_with_max_lookback(
-    rows: int | np.integer, max_lookback: ir.IntervalValue
-) -> RowsWithMaxLookback:
-    """Create a bound preceding value for use with trailing window functions.
-
-    Parameters
-    ----------
-    rows
-        Number of rows
-    max_lookback
-        Maximum lookback in time
-
-    Returns
-    -------
-    RowsWithMaxLookback
-        A named tuple of rows and maximum look-back in time.
-
-    """
-    return RowsWithMaxLookback(rows, max_lookback)
-
-
 def window(
     preceding=None,
     following=None,
@@ -1658,12 +1630,6 @@ def window(
         A window frame
 
     """
-    if isinstance(preceding, RowsWithMaxLookback):
-        max_lookback = preceding.max_lookback
-        preceding = preceding.rows
-    else:
-        max_lookback = None
-
     has_rows = rows is not None
     has_range = range is not None
     has_between = between is not None
@@ -1673,12 +1639,7 @@ def window(
             "Must only specify either `rows`, `range`, `between` or `preceding`/`following`"
         )
 
-    builder = (
-        bl.LegacyWindowBuilder()
-        .group_by(group_by)
-        .order_by(order_by)
-        .lookback(max_lookback)
-    )
+    builder = bl.LegacyWindowBuilder().group_by(group_by).order_by(order_by)
     if has_rows:
         return builder.rows(*rows)
     elif has_range:
@@ -1716,17 +1677,10 @@ def rows_window(preceding=None, following=None, group_by=None, order_by=None):
         A window frame
 
     """
-    if isinstance(preceding, RowsWithMaxLookback):
-        max_lookback = preceding.max_lookback
-        preceding = preceding.rows
-    else:
-        max_lookback = None
-
     return (
         bl.LegacyWindowBuilder()
         .group_by(group_by)
         .order_by(order_by)
-        .lookback(max_lookback)
         .preceding_following(preceding, following, how="rows")
     )
 

ibis/expr/builders.py

@@ -147,7 +147,6 @@ class WindowBuilder(Builder):
     end: Optional[RangeWindowBoundary] = None
     groupings: VarTuple[Union[str, Resolver, ops.Value]] = ()
     orderings: VarTuple[Union[str, Resolver, ops.Value]] = ()
-    max_lookback: Optional[ops.Value[dt.Interval]] = None
 
     @attribute
     def _table(self):
@@ -156,7 +155,6 @@ def _table(self):
             self.end,
             *self.groupings,
             *self.orderings,
-            self.max_lookback,
         )
         valuerels = (v.relations for v in inputs if isinstance(v, ops.Value))
         relations = frozenset().union(*valuerels)
@@ -227,9 +225,6 @@ def group_by(self, expr) -> Self:
     def order_by(self, expr) -> Self:
         return self.copy(orderings=self.orderings + util.promote_tuple(expr))
 
-    def lookback(self, value) -> Self:
-        return self.copy(max_lookback=value)
-
     @annotated
     def bind(self, table: Optional[ops.Relation]):
         table = table or self._table
@@ -255,7 +250,6 @@ def bind_value(value):
                 end=self.end,
                 group_by=groupings,
                 order_by=orderings,
-                max_lookback=self.max_lookback,
             )
         elif self.how == "range":
             return ops.RangeWindowFrame(

ibis/expr/operations/window.py

@@ -100,21 +100,6 @@ class RowsWindowFrame(WindowFrame):
     how = "rows"
     start: Optional[WindowBoundary[dt.Integer]] = None
     end: Optional[WindowBoundary] = None
-    max_lookback: Optional[Value[dt.Interval]] = None
-
-    def __init__(self, max_lookback, order_by, **kwargs):
-        if max_lookback:
-            # TODO(kszucs): this should belong to a timeseries extension rather than
-            # the core window operation
-            if len(order_by) != 1:
-                raise com.IbisTypeError(
-                    "`max_lookback` window must be ordered by a single column"
-                )
-            if not order_by[0].dtype.is_timestamp():
-                raise com.IbisTypeError(
-                    "`max_lookback` window must be ordered by a timestamp column"
-                )
-        super().__init__(max_lookback=max_lookback, order_by=order_by, **kwargs)
 
 
 @public

ibis/tests/expr/test_window_frames.py

@@ -1,7 +1,6 @@
 from __future__ import annotations
 
 import numpy as np
-import pandas as pd
 import pytest
 from pytest import param
 
@@ -11,7 +10,7 @@
 import ibis.expr.datatypes as dt
 import ibis.expr.operations as ops
 from ibis.common.annotations import ValidationError
-from ibis.common.exceptions import IbisInputError, IbisTypeError
+from ibis.common.exceptions import IbisInputError
 from ibis.common.patterns import NoMatch, Pattern
 
 
@@ -260,12 +259,6 @@ def test_window_api_properly_determines_how():
     assert ibis.window(following=3.14).how == "range"
     assert ibis.window(following=3).how == "rows"
 
-    mlb1 = ibis.rows_with_max_lookback(3, ibis.interval(months=3))
-    mlb2 = ibis.rows_with_max_lookback(3, ibis.interval(pd.Timedelta(days=3)))
-    mlb3 = ibis.rows_with_max_lookback(np.int64(7), ibis.interval(months=3))
-    for mlb in [mlb1, mlb2, mlb3]:
-        assert ibis.window(mlb).how == "rows"
-
 
 def test_window_api_mutually_exclusive_options():
     with pytest.raises(IbisInputError):
@@ -300,13 +293,6 @@ def test_window_builder_methods(alltypes):
     expected = ibis.window(preceding=5, following=1, group_by=t.a, order_by=[t.b, t.d])
     assert w3 == expected
 
-    w4 = ibis.trailing_window(ibis.rows_with_max_lookback(3, ibis.interval(months=3)))
-    w5 = w4.group_by(t.a)
-    expected = ibis.trailing_window(
-        ibis.rows_with_max_lookback(3, ibis.interval(months=3)), group_by=t.a
-    )
-    assert w5 == expected
-
 
 @pytest.mark.parametrize(
     ["method", "is_preceding"],
@@ -338,33 +324,13 @@ def test_window_api_preceding_following(method, is_preceding):
     p4 = method(t.a).op()
     assert p4.value == t.a.op()
 
-    # TODO(kszucs): support deferred
-
 
 def test_window_api_trailing_range():
     t = ibis.table([("col", "int64")], name="t")
     w = ibis.trailing_range_window(ibis.interval(days=1), order_by="col")
     w.bind(t)
 
 
-def test_window_api_max_rows_with_lookback(alltypes):
-    t = alltypes
-    mlb = ibis.rows_with_max_lookback(3, ibis.interval(days=5))
-    window = ibis.trailing_window(mlb, order_by=t.i)
-
-    window = ibis.trailing_window(mlb)
-    with pytest.raises(IbisTypeError):
-        t.f.lag().over(window)
-
-    window = ibis.trailing_window(mlb, order_by=t.a)
-    with pytest.raises(IbisTypeError):
-        t.f.lag().over(window)
-
-    window = ibis.trailing_window(mlb, order_by=[t.i, t.a])
-    with pytest.raises(IbisTypeError):
-        t.f.lag().over(window)
-
-
 @pytest.mark.parametrize(
     ["a", "b"],
     [