Github user pwoody commented on a diff in the pull request:
https://github.com/apache/spark/pull/15835#discussion_r87560812
--- Diff:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala
---
@@ -272,6 +275,83 @@ class ParquetFileFormat
true
}
+ override def getSplits(fileIndex: FileIndex,
+ fileStatus: FileStatus,
+ filters: Seq[Filter],
+ schema: StructType,
+ hadoopConf: Configuration): Seq[FileSplit] = {
+ if (filters.isEmpty) {
+ // Return immediately to save FileSystem overhead
+ super.getSplits(fileIndex, fileStatus, filters, schema, hadoopConf)
+ } else {
+ val filePath = fileStatus.getPath
+ val rootOption: Option[Path] = fileIndex.rootPaths
+ .find(root => filePath.toString.startsWith(root.toString))
+ val metadataOption = rootOption.flatMap(getMetadataForPath(filePath,
_, hadoopConf))
+ // If the metadata exists, filter the splits.
+ // Otherwise, fall back to the default implementation.
+ metadataOption
+ .map(filterToSplits(fileStatus, _, rootOption.get, filters,
schema, hadoopConf))
+ .getOrElse(super.getSplits(fileIndex, fileStatus, filters, schema,
hadoopConf))
+ }
+ }
+
+ private def filterToSplits(fileStatus: FileStatus,
+ metadata: ParquetMetadata,
+ metadataRoot: Path,
+ filters: Seq[Filter],
+ schema: StructType,
+ hadoopConf: Configuration): Seq[FileSplit] = {
+ val metadataBlocks = metadata.getBlocks
+ val parquetSchema = metadata.getFileMetaData.getSchema
+ val filter = FilterCompat.get(filters
+ .flatMap(ParquetFilters.createFilter(schema, _))
+ .reduce(FilterApi.and))
+ val filteredMetadata =
+ RowGroupFilter.filterRowGroups(filter, metadataBlocks,
parquetSchema).asScala
+ filteredMetadata.flatMap(bmd => {
+ val bmdPath = new Path(metadataRoot, bmd.getPath)
+ val fsPath = fileStatus.getPath
+ if (bmdPath == fsPath) {
+ Some(new FileSplit(bmdPath, bmd.getStartingPos,
bmd.getTotalByteSize, Array.empty))
+ } else {
+ None
+ }
+ })
+ }
+
+ private def getMetadataForPath(filePath: Path,
+ rootPath: Path,
+ conf: Configuration):
Option[ParquetMetadata] = {
+ val fs = rootPath.getFileSystem(conf)
+ try {
+ val stat = fs.getFileStatus(rootPath)
+ // Mimic Parquet behavior. If given a directory, find the underlying
_metadata file
+ // If given a single file, check the parent directory for a
_metadata file
+ val directory = if (stat.isDirectory) stat.getPath else
stat.getPath.getParent
+ val metadataFile = new Path(directory,
ParquetFileWriter.PARQUET_METADATA_FILE)
+ val metadata =
+ ParquetFileReader.readFooter(conf, metadataFile,
ParquetMetadataConverter.NO_FILTER)
+
+ // Ensure that the metadata has an entry for the file.
+ // If it does not, do not filter at this stage.
+ val matchingBlockExists = metadata.getBlocks.asScala.exists(bmd => {
--- End diff --
By default, writes won't merge parquet metadata unfortunately. So if you
use SaveMode.Append on an existing parquet directory it will re-write it.
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