perf: Use promote_offsets for consistent row number generation for index.get_loc (#1957)

* perf: use promote_offsets for consistent row number generation for
index.get_loc

* remove unused import

* work on lint

Author: shuoweil

bigframes/core/indexes/base.py

@@ -27,16 +27,12 @@
 import pandas
 
 from bigframes import dtypes
-from bigframes.core.array_value import ArrayValue
 import bigframes.core.block_transforms as block_ops
 import bigframes.core.blocks as blocks
 import bigframes.core.expression as ex
-import bigframes.core.identifiers as ids
-import bigframes.core.nodes as nodes
 import bigframes.core.ordering as order
 import bigframes.core.utils as utils
 import bigframes.core.validations as validations
-import bigframes.core.window_spec as window_spec
 import bigframes.dtypes
 import bigframes.formatting_helpers as formatter
 import bigframes.operations as ops
@@ -272,37 +268,20 @@ def get_loc(self, key) -> typing.Union[int, slice, "bigframes.series.Series"]:
         # Get the index column from the block
         index_column = self._block.index_columns[0]
 
-        # Apply row numbering to the original data
-        row_number_column_id = ids.ColumnId.unique()
-        window_node = nodes.WindowOpNode(
-            child=self._block._expr.node,
-            expression=ex.NullaryAggregation(agg_ops.RowNumberOp()),
-            window_spec=window_spec.unbound(),
-            output_name=row_number_column_id,
-            never_skip_nulls=True,
-        )
-
-        windowed_array = ArrayValue(window_node)
-        windowed_block = blocks.Block(
-            windowed_array,
-            index_columns=self._block.index_columns,
-            column_labels=self._block.column_labels.insert(
-                len(self._block.column_labels), None
-            ),
-            index_labels=self._block._index_labels,
+        # Use promote_offsets to get row numbers (similar to argmax/argmin implementation)
+        block_with_offsets, offsets_id = self._block.promote_offsets(
+            "temp_get_loc_offsets_"
         )
 
         # Create expression to find matching positions
         match_expr = ops.eq_op.as_expr(ex.deref(index_column), ex.const(key))
-        windowed_block, match_col_id = windowed_block.project_expr(match_expr)
+        block_with_offsets, match_col_id = block_with_offsets.project_expr(match_expr)
 
         # Filter to only rows where the key matches
-        filtered_block = windowed_block.filter_by_id(match_col_id)
+        filtered_block = block_with_offsets.filter_by_id(match_col_id)
 
-        # Check if key exists at all by counting on the filtered block
-        count_agg = ex.UnaryAggregation(
-            agg_ops.count_op, ex.deref(row_number_column_id.name)
-        )
+        # Check if key exists at all by counting
+        count_agg = ex.UnaryAggregation(agg_ops.count_op, ex.deref(offsets_id))
         count_result = filtered_block._expr.aggregate([(count_agg, "count")])
         count_scalar = self._block.session._executor.execute(
             count_result
@@ -313,9 +292,7 @@ def get_loc(self, key) -> typing.Union[int, slice, "bigframes.series.Series"]:
 
         # If only one match, return integer position
         if count_scalar == 1:
-            min_agg = ex.UnaryAggregation(
-                agg_ops.min_op, ex.deref(row_number_column_id.name)
-            )
+            min_agg = ex.UnaryAggregation(agg_ops.min_op, ex.deref(offsets_id))
             position_result = filtered_block._expr.aggregate([(min_agg, "position")])
             position_scalar = self._block.session._executor.execute(
                 position_result
@@ -325,32 +302,24 @@ def get_loc(self, key) -> typing.Union[int, slice, "bigframes.series.Series"]:
         # Handle multiple matches based on index monotonicity
         is_monotonic = self.is_monotonic_increasing or self.is_monotonic_decreasing
         if is_monotonic:
-            return self._get_monotonic_slice(filtered_block, row_number_column_id)
+            return self._get_monotonic_slice(filtered_block, offsets_id)
         else:
             # Return boolean mask for non-monotonic duplicates
-            mask_block = windowed_block.select_columns([match_col_id])
-            # Reset the index to use positional integers instead of original index values
+            mask_block = block_with_offsets.select_columns([match_col_id])
             mask_block = mask_block.reset_index(drop=True)
-            # Ensure correct dtype and name to match pandas behavior
             result_series = bigframes.series.Series(mask_block)
             return result_series.astype("boolean")
 
-    def _get_monotonic_slice(
-        self, filtered_block, row_number_column_id: "ids.ColumnId"
-    ) -> slice:
+    def _get_monotonic_slice(self, filtered_block, offsets_id: str) -> slice:
         """Helper method to get a slice for monotonic duplicates with an optimized query."""
         # Combine min and max aggregations into a single query for efficiency
         min_max_aggs = [
             (
-                ex.UnaryAggregation(
-                    agg_ops.min_op, ex.deref(row_number_column_id.name)
-                ),
+                ex.UnaryAggregation(agg_ops.min_op, ex.deref(offsets_id)),
                 "min_pos",
             ),
             (
-                ex.UnaryAggregation(
-                    agg_ops.max_op, ex.deref(row_number_column_id.name)
-                ),
+                ex.UnaryAggregation(agg_ops.max_op, ex.deref(offsets_id)),
                 "max_pos",
             ),
         ]

third_party/bigframes_vendored/pandas/core/indexes/base.py

@@ -767,7 +767,7 @@ def get_loc(
             1     True
             2    False
             3     True
-            Name: nan, dtype: boolean
+            dtype: boolean
 
         Args:
             key: Label to get the location for.