viirya commented on a change in pull request #27728:
[SPARK-25556][SPARK-17636][SPARK-31026][SQL][test-hive1.2] Nested Column
Predicate Pushdown for Parquet
URL: https://github.com/apache/spark/pull/27728#discussion_r387264452
##########
File path:
sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFilters.scala
##########
@@ -49,15 +49,34 @@ class ParquetFilters(
pushDownInFilterThreshold: Int,
caseSensitive: Boolean) {
// A map which contains parquet field name and data type, if predicate push
down applies.
- private val nameToParquetField : Map[String, ParquetField] = {
- // Here we don't flatten the fields in the nested schema but just look up
through
- // root fields. Currently, accessing to nested fields does not push down
filters
- // and it does not support to create filters for them.
- val primitiveFields =
-
schema.getFields.asScala.filter(_.isPrimitive).map(_.asPrimitiveType()).map { f
=>
- f.getName -> ParquetField(f.getName,
- ParquetSchemaType(f.getOriginalType,
- f.getPrimitiveTypeName, f.getTypeLength, f.getDecimalMetadata))
+ // The keys are the column names. For nested column, `dot` will be used as a
separator.
+ // For column name that contains `dot`, backquote will be used.
+ // See `org.apache.spark.sql.connector.catalog.quote` for implementation
details.
+ private val nameToParquetField : Map[String, ParquetPrimitiveField] = {
+ // Recursively traverse the parquet schema to get primitive fields that
can be pushed-down.
+ // `parentFieldNames` is used to keep track of the current nested level
when traversing.
+ def getPrimitiveFields(
+ fields: Seq[Type],
+ parentFieldNames: Array[String] = Array.empty):
Seq[ParquetPrimitiveField] = {
+ fields.flatMap {
+ case p: PrimitiveType =>
+ Some(ParquetPrimitiveField(fieldNames = parentFieldNames :+
p.getName,
+ fieldType = ParquetSchemaType(p.getOriginalType,
+ p.getPrimitiveTypeName, p.getTypeLength, p.getDecimalMetadata)))
+ // Note that when g is a `Struct`, `g.getOriginalType` is `null`.
+ // When g is a `Map`, `g.getOriginalType` is `MAP`.
+ // When g is a `List`, `g.getOriginalType` is `LIST`.
+ case g: GroupType if g.getOriginalType == null =>
+ getPrimitiveFields(g.getFields.asScala, parentFieldNames :+
g.getName)
+ // Parquet only supports push-down for primitive types; as a result,
Map and List types
+ // are removed.
+ case _ => None
+ }
+ }
+
+ val primitiveFields = getPrimitiveFields(schema.getFields.asScala).map {
field =>
+ import
org.apache.spark.sql.connector.catalog.CatalogV2Implicits.MultipartIdentifierHelper
Review comment:
nit: move `import` outside `map?
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