Github user viirya commented on a diff in the pull request:
https://github.com/apache/spark/pull/10972#discussion_r51221351
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
---
@@ -799,9 +799,26 @@ private[sql] object ParquetRelation extends Logging {
assumeInt96IsTimestamp = assumeInt96IsTimestamp,
writeLegacyParquetFormat = writeLegacyParquetFormat)
- footers.map { footer =>
- ParquetRelation.readSchemaFromFooter(footer, converter)
- }.reduceLeftOption(_ merge _).iterator
+ if (footers.isEmpty) {
+ Iterator.empty
+ } else {
+ var mergedSchema = StructType(Nil)
+ footers.foreach { footer =>
+ val schema = ParquetRelation.readSchemaFromFooter(footer,
converter)
+ try {
+ mergedSchema = mergedSchema.merge(schema)
--- End diff --
Can we get the schema from first footer and then go through this loop for
remaining footers? Because you merge the first schema with an empty schema, I
think the all fields in merged schema will be optional in their metadata. So
the pushing down of filters will not normally work.
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