maropu commented on a change in pull request #24158: [SPARK-26847][SQL] Pruning
nested serializers from object serializers: MapType support
URL: https://github.com/apache/spark/pull/24158#discussion_r268032776
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/objects.scala
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@@ -132,49 +130,74 @@ object ObjectSerializerPruning extends Rule[LogicalPlan]
{
fields.map(f => collectStructType(f.dataType, structs))
case ArrayType(elementType, _) =>
collectStructType(elementType, structs)
+ case MapType(_, valueType, _) =>
+ // Because we can't select a field from struct in key, so we skip key
type.
+ collectStructType(valueType, structs)
case _ =>
}
structs
}
+ /**
+ * This method returns pruned `CreateNamedStruct` expression given an
original `CreateNamedStruct`
+ * and a pruned `StructType`.
+ */
+ private def pruneNamedStruct(struct: CreateNamedStruct, prunedType:
StructType) = {
+ // Filters out the pruned fields.
+ val prunedFields = struct.nameExprs.zip(struct.valExprs).filter { case
(nameExpr, _) =>
+ val name = nameExpr.eval(EmptyRow).toString
+ prunedType.fieldNames.exists { fieldName =>
+ if (SQLConf.get.caseSensitiveAnalysis) {
+ fieldName.equals(name)
+ } else {
+ fieldName.equalsIgnoreCase(name)
+ }
+ }
+ }.flatMap(pair => Seq(pair._1, pair._2))
+
+ CreateNamedStruct(prunedFields)
+ }
+
+ /**
+ * When we change nested serializer data type, `If` expression will be
unresolved because
+ * literal null's data type doesn't match now. We need to align it with new
data type.
+ * Note: we should do `transformUp` explicitly to change data types.
+ */
+ private def alignNullTypeInIf(expr: Expression) = expr.transformUp {
+ case i @ If(_: IsNull, Literal(null, dt), ser) if
!dt.sameType(ser.dataType) =>
+ i.copy(trueValue = Literal(null, ser.dataType))
+ }
+
/**
* This method prunes given serializer expression by given pruned data type.
For example,
* given a serializer creating struct(a int, b int) and pruned data type
struct(a int),
- * this method returns pruned serializer creating struct(a int). For now it
supports to
- * prune nested fields in struct and array of struct.
- * TODO(SPARK-26847): support to prune nested fields in key and value of map
type.
+ * this method returns pruned serializer creating struct(a int).
*/
def pruneSerializer(
serializer: NamedExpression,
prunedDataType: DataType): NamedExpression = {
val prunedStructTypes = collectStructType(prunedDataType,
ArrayBuffer.empty[StructType])
var structTypeIndex = 0
- val prunedSerializer = serializer.transformDown {
+ val transformedSerializer = serializer.transformDown {
+ case m: ExternalMapToCatalyst =>
+ val valueStructs = m.valueConverter.collect {
Review comment:
`valueStructs` not used?
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