George Sakkis created ARROW-4076:
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Summary: [Python] schema validation and filters
Key: ARROW-4076
URL: https://issues.apache.org/jira/browse/ARROW-4076
Project: Apache Arrow
Issue Type: Bug
Components: Python
Reporter: George Sakkis
Currently [schema
validation|https://github.com/apache/arrow/blob/758bd557584107cb336cbc3422744dacd93978af/python/pyarrow/parquet.py#L900]
of {{ParquetDataset}} takes place before filtering. This may raise a
{{ValueError}}if the schema is different in some dataset pieces, even if these
pieces would be subsequently filtered out. I think validation should happen
after filtering to prevent such spurious errors:
{noformat}
--- a/pyarrow/parquet.py
+++ b/pyarrow/parquet.py
@@ -878,13 +878,13 @@
if split_row_groups:
raise NotImplementedError("split_row_groups not yet implemented")
- if validate_schema:
- self.validate_schemas()
-
if filters is not None:
filters = _check_filters(filters)
self._filter(filters)
+ if validate_schema:
+ self.validate_schemas()
+
def validate_schemas(self):
open_file = self._get_open_file_func()
{noformat}
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