Tidying up

Author: Alexey Kudinkin

hudi-spark-datasource/hudi-spark3/src/main/scala/org/apache/spark/sql/hudi/analysis/HoodieSpark3Analysis.scala

@@ -45,6 +45,8 @@ import scala.collection.JavaConverters.mapAsJavaMapConverter
  * Since Hudi relations don't currently implement DS V2 Read API, we have to fallback to V1 here.
  * Such fallback will have considerable performance impact, therefore it's only performed in cases
  * where V2 API have to be used. Currently only such use-case is using of Schema Evolution feature
+ *
+ * Check out HUDI-4178 for more details
  */
 class HoodieDataSourceV2ToV1Fallback(sparkSession: SparkSession) extends Rule[LogicalPlan]
   with ProvidesHoodieConfig {
@@ -129,7 +131,6 @@ class HoodieSpark3Analysis(sparkSession: SparkSession) extends Rule[LogicalPlan]
 
 /**
  * Rule for resolve hoodie's extended syntax or rewrite some logical plan.
- * @param sparkSession
  */
 case class HoodieSpark3ResolveReferences(sparkSession: SparkSession) extends Rule[LogicalPlan]
   with SparkAdapterSupport with ProvidesHoodieConfig {

hudi-spark-datasource/hudi-spark3/src/main/scala/org/apache/spark/sql/hudi/catalog/HoodieCatalog.scala

@@ -115,7 +115,14 @@ class HoodieCatalog extends DelegatingCatalogExtension
 
         val schemaEvolutionEnabled: Boolean = spark.sessionState.conf.getConfString(DataSourceReadOptions.SCHEMA_EVOLUTION_ENABLED.key,
           DataSourceReadOptions.SCHEMA_EVOLUTION_ENABLED.defaultValue.toString).toBoolean
-        // TODO elaborate
+
+        // NOTE: PLEASE READ CAREFULLY
+        //
+        // Since Hudi relations don't currently implement DS V2 Read API, we by default fallback to V1 here.
+        // Such fallback will have considerable performance impact, therefore it's only performed in cases
+        // where V2 API have to be used. Currently only such use-case is using of Schema Evolution feature
+        //
+        // Check out HUDI-4178 for more details
         if (schemaEvolutionEnabled) {
           v2Table
         } else {