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[SPARK-13070][SQL] Better error message when Parquet schema merging fails #10972

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liancheng wants to merge 3 commits into from
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[SPARK-13070][SQL] Better error message when Parquet schema merging fails #10972

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1ce61a4
Better error message when Parquet schema merging fails
liancheng Jan 29, 2016
bfe4987
Addresses PR comments
liancheng Jan 29, 2016
2e5eddb
Addresses PR comments
liancheng Jan 29, 2016
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6 changes: 3 additions & 3 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/types/StructType.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -402,13 +402,13 @@ object StructType extends AbstractDataType {
if ((leftPrecision == rightPrecision) && (leftScale == rightScale)) {
DecimalType(leftPrecision, leftScale)
} else if ((leftPrecision != rightPrecision) && (leftScale != rightScale)) {
throw new SparkException("Failed to merge Decimal Tpes with incompatible " +
throw new SparkException("Failed to merge decimal types with incompatible " +
s"precision $leftPrecision and $rightPrecision & scale $leftScale and $rightScale")
} else if (leftPrecision != rightPrecision) {
throw new SparkException("Failed to merge Decimal Tpes with incompatible " +
throw new SparkException("Failed to merge decimal types with incompatible " +
s"precision $leftPrecision and $rightPrecision")
} else {
throw new SparkException("Failed to merge Decimal Tpes with incompatible " +
throw new SparkException("Failed to merge decimal types with incompatible " +
s"scala $leftScale and $rightScale")
}

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18 changes: 15 additions & 3 deletions ...e/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
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Expand Up @@ -799,9 +799,21 @@ 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)
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@viirya viirya Jan 29, 2016

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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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@liancheng liancheng Jan 29, 2016

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Yeah you'll right, filter push-down can be affected due to #9940 (which I just merged today). Thanks for pointing this out!

} catch { case cause: SparkException =>
throw new SparkException(
s"Failed merging schema of file ${footer.getFile}:\n${schema.treeString}", cause)
}
}
Iterator.single(mergedSchema)
}
}.collect()

partiallyMergedSchemas.reduceLeftOption(_ merge _)
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15 changes: 15 additions & 0 deletions ...rc/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetSchemaSuite.scala
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Expand Up @@ -22,6 +22,7 @@ import scala.reflect.runtime.universe.TypeTag

import org.apache.parquet.schema.MessageTypeParser

import org.apache.spark.SparkException
import org.apache.spark.sql.catalyst.ScalaReflection
import org.apache.spark.sql.test.SharedSQLContext
import org.apache.spark.sql.types._
Expand Down Expand Up @@ -449,6 +450,20 @@ class ParquetSchemaSuite extends ParquetSchemaTest {
}.getMessage.contains("detected conflicting schemas"))
}

test("schema merging failure error message") {
withTempPath { dir =>
val path = dir.getCanonicalPath
sqlContext.range(3).write.parquet(s"$path/p=1")
sqlContext.range(3).selectExpr("CAST(id AS INT) AS id").write.parquet(s"$path/p=2")

val message = intercept[SparkException] {
sqlContext.read.option("mergeSchema", "true").parquet(path).schema
}.getMessage

assert(message.contains("Failed merging schema of file"))
}
}

// =======================================================
// Tests for converting Parquet LIST to Catalyst ArrayType
// =======================================================
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