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Enable predicate pushdown in read_parquet #886

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Enable predicate pushdown in read_parquet #886

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32 changes: 24 additions & 8 deletions dask_expr/io/parquet.py
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Original file line number Diff line number Diff line change
Expand Up @@ -39,12 +39,15 @@
And,
Blockwise,
Expr,
Filter,
Index,
Lengths,
Literal,
Or,
Projection,
are_co_aligned,
determine_column_projection,
is_filter_pushdown_available,
)
from dask_expr._reductions import Len
from dask_expr._util import _convert_to_list, _tokenize_deterministic
Expand Down Expand Up @@ -452,6 +455,7 @@ class ReadParquet(PartitionsFiltered, BlockwiseIO):
}
_pq_length_stats = None
_absorb_projections = True
_filter_passthrough = True

def _tree_repr_argument_construction(self, i, op, header):
if self._parameters[i] == "_dataset_info_cache":
Expand Down Expand Up @@ -486,6 +490,22 @@ def _simplify_up(self, parent, dependents):
if isinstance(parent, Projection):
return super()._simplify_up(parent, dependents)

if (
isinstance(parent, Filter)
and isinstance(parent.predicate, (LE, GE, LT, GT, EQ, NE, And, Or))
and is_filter_pushdown_available(self, parent, dependents)
):
# Predicate pushdown
filters = _DNF.extract_pq_filters(self, parent.predicate)
if filters._filters is not None:
return self.substitute_parameters(
{
"filters": filters.combine(
self.operand("filters")
).to_list_tuple()
}
)

if isinstance(parent, Lengths):
_lengths = self._get_lengths()
if _lengths:
Expand Down Expand Up @@ -888,19 +908,15 @@ def combine(self, other: _DNF | _And | _Or | list | tuple | None) -> _DNF:
def extract_pq_filters(cls, pq_expr: ReadParquet, predicate_expr: Expr) -> _DNF:
_filters = None
if isinstance(predicate_expr, (LE, GE, LT, GT, EQ, NE)):
if (
isinstance(predicate_expr.left, ReadParquet)
and predicate_expr.left.path == pq_expr.path
and not isinstance(predicate_expr.right, Expr)
if are_co_aligned(pq_expr, predicate_expr.left) and not isinstance(
predicate_expr.right, Expr
):
op = predicate_expr._operator_repr
column = predicate_expr.left.columns[0]
value = predicate_expr.right
_filters = (column, op, value)
elif (
isinstance(predicate_expr.right, ReadParquet)
and predicate_expr.right.path == pq_expr.path
and not isinstance(predicate_expr.left, Expr)
elif are_co_aligned(pq_expr, predicate_expr.right) and not isinstance(
predicate_expr.left, Expr
):
# Simple dict to make sure field comes first in filter
flip = {LE: GE, LT: GT, GE: LE, GT: LT}
Expand Down