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Posted to commits@hudi.apache.org by GitBox <gi...@apache.org> on 2022/07/22 03:35:25 UTC

[GitHub] [hudi] alexeykudinkin commented on a diff in pull request #5708: [HUDI-4420][Stacked on 5430] Fixing table schema delineation on partition/data schema for Spark relations

alexeykudinkin commented on code in PR #5708:
URL: https://github.com/apache/hudi/pull/5708#discussion_r927259929


##########
hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieBaseRelation.scala:
##########
@@ -564,42 +538,57 @@ abstract class HoodieBaseRelation(val sqlContext: SQLContext,
     //       we have to eagerly initialize all of the readers even though only one specific to the type
     //       of the file being read will be used. This is required to avoid serialization of the whole
     //       relation (containing file-index for ex) and passing it to the executor
-    val reader = tableBaseFileFormat match {
-      case HoodieFileFormat.PARQUET =>
-        HoodieDataSourceHelper.buildHoodieParquetReader(
-          sparkSession = spark,
-          dataSchema = dataSchema.structTypeSchema,
-          partitionSchema = partitionSchema,
-          requiredSchema = requiredSchema.structTypeSchema,
-          filters = filters,
-          options = options,
-          hadoopConf = hadoopConf,
-          // We're delegating to Spark to append partition values to every row only in cases
-          // when these corresponding partition-values are not persisted w/in the data file itself
-          appendPartitionValues = shouldExtractPartitionValuesFromPartitionPath
-        )
+    val (read: (PartitionedFile => Iterator[InternalRow]), schema: StructType) =
+      tableBaseFileFormat match {
+        case HoodieFileFormat.PARQUET =>
+          (
+            HoodieDataSourceHelper.buildHoodieParquetReader(
+              sparkSession = spark,
+              dataSchema = dataSchema.structTypeSchema,
+              partitionSchema = partitionSchema,
+              requiredSchema = requiredSchema.structTypeSchema,
+              filters = filters,
+              options = options,
+              hadoopConf = hadoopConf,
+              // We're delegating to Spark to append partition values to every row only in cases
+              // when these corresponding partition-values are not persisted w/in the data file itself
+              appendPartitionValues = shouldExtractPartitionValuesFromPartitionPath
+            ),
+            // Since partition values by default are omitted, and not persisted w/in data-files by Spark,
+            // data-file readers (such as [[ParquetFileFormat]]) have to inject partition values while reading
+            // the data. As such, actual full schema produced by such reader is composed of
+            //    a) Prepended partition column values
+            //    b) Data-file schema (projected or not)
+            StructType(partitionSchema.fields ++ requiredSchema.structTypeSchema.fields)

Review Comment:
   It was actually a typo -- partition columns are actually appended (Spark's ParquetFileFormat has it incorrectly [here](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala#L237)



##########
hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/hudi/HoodieBaseRelation.scala:
##########
@@ -564,42 +538,57 @@ abstract class HoodieBaseRelation(val sqlContext: SQLContext,
     //       we have to eagerly initialize all of the readers even though only one specific to the type
     //       of the file being read will be used. This is required to avoid serialization of the whole
     //       relation (containing file-index for ex) and passing it to the executor
-    val reader = tableBaseFileFormat match {
-      case HoodieFileFormat.PARQUET =>
-        HoodieDataSourceHelper.buildHoodieParquetReader(
-          sparkSession = spark,
-          dataSchema = dataSchema.structTypeSchema,
-          partitionSchema = partitionSchema,
-          requiredSchema = requiredSchema.structTypeSchema,
-          filters = filters,
-          options = options,
-          hadoopConf = hadoopConf,
-          // We're delegating to Spark to append partition values to every row only in cases
-          // when these corresponding partition-values are not persisted w/in the data file itself
-          appendPartitionValues = shouldExtractPartitionValuesFromPartitionPath
-        )
+    val (read: (PartitionedFile => Iterator[InternalRow]), schema: StructType) =
+      tableBaseFileFormat match {
+        case HoodieFileFormat.PARQUET =>
+          (
+            HoodieDataSourceHelper.buildHoodieParquetReader(
+              sparkSession = spark,
+              dataSchema = dataSchema.structTypeSchema,
+              partitionSchema = partitionSchema,
+              requiredSchema = requiredSchema.structTypeSchema,
+              filters = filters,
+              options = options,
+              hadoopConf = hadoopConf,
+              // We're delegating to Spark to append partition values to every row only in cases
+              // when these corresponding partition-values are not persisted w/in the data file itself
+              appendPartitionValues = shouldExtractPartitionValuesFromPartitionPath
+            ),
+            // Since partition values by default are omitted, and not persisted w/in data-files by Spark,
+            // data-file readers (such as [[ParquetFileFormat]]) have to inject partition values while reading
+            // the data. As such, actual full schema produced by such reader is composed of
+            //    a) Prepended partition column values
+            //    b) Data-file schema (projected or not)
+            StructType(partitionSchema.fields ++ requiredSchema.structTypeSchema.fields)

Review Comment:
   It was actually a typo -- partition columns are actually appended (Spark's ParquetFileFormat has it incorrectly [here](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetFileFormat.scala#L237))



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