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Add make_reader support for parquet partitioned on more than one key #488

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Add make_reader support for parquet partitioned on more than one key #488

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8f4949d
Add support for double partitioning
jamesprinc3 Feb 14, 2020
db6f15c
Rm blank line
jamesprinc3 Feb 14, 2020
bd6ddfd
add empty line
jamesprinc3 Feb 14, 2020
697f5c2
Update test_predicates.py
jamesprinc3 Feb 14, 2020
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4 changes: 1 addition & 3 deletions petastorm/reader.py
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Original file line number Diff line number Diff line change
Expand Up @@ -532,9 +532,7 @@ def _apply_predicate_to_row_groups(self, dataset, row_groups, predicate):
raise ValueError('predicate parameter is expected to be derived from PredicateBase')
predicate_fields = predicate.get_fields()

if set(predicate_fields) == dataset.partitions.partition_names:
assert len(dataset.partitions.partition_names) == 1, \
'Datasets with only a single partition level supported at the moment'
if set(predicate_fields).issubset(dataset.partitions.partition_names):

filtered_row_group_indexes = []
for piece_index, piece in enumerate(row_groups):
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6 changes: 5 additions & 1 deletion petastorm/tests/test_predicates.py
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Expand Up @@ -154,12 +154,14 @@ def test_predicate_on_partitioned_dataset(tmpdir):
"""
TestSchema = Unischema('TestSchema', [
UnischemaField('id', np.int32, (), ScalarCodec(IntegerType()), False),
UnischemaField('id2', np.int32, (), ScalarCodec(IntegerType()), False),
UnischemaField('test_field', np.int32, (), ScalarCodec(IntegerType()), False),
])

def test_row_generator(x):
"""Returns a single entry in the generated dataset."""
return {'id': x,
'id2': x+1,
'test_field': x*x}

rowgroup_size_mb = 256
Expand All @@ -177,11 +179,13 @@ def test_row_generator(x):

spark.createDataFrame(rows_rdd, TestSchema.as_spark_schema()) \
.write \
.partitionBy('id') \
.partitionBy('id', 'id2') \
.parquet(dataset_url)

with make_reader(dataset_url, predicate=in_lambda(['id'], lambda x: x == 3)) as reader:
assert next(reader).id == 3
with make_reader(dataset_url, predicate=in_lambda(['id2'], lambda x: x == 5)) as reader:
assert next(reader).id == 5
with make_reader(dataset_url, predicate=in_lambda(['id'], lambda x: x == '3')) as reader:
with pytest.raises(StopIteration):
# Predicate should have selected none, so a StopIteration should be raised.
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