avoid computation without wscg

spark/src/main/scala/org/apache/spark/sql/delta/SnapshotState.scala

@@ -27,6 +27,7 @@ import org.apache.spark.sql.util.ScalaExtensions._
 
 import org.apache.spark.sql.{Column, DataFrame}
 import org.apache.spark.sql.functions.{coalesce, col, collect_set, count, last, lit, sum}
+import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.util.Utils
 
 
@@ -145,8 +146,16 @@ trait SnapshotStateManager extends DeltaLogging { self: Snapshot =>
    * A Map of alias to aggregations which needs to be done to calculate the `computedState`
    */
   protected def aggregationsToComputeState: Map[String, Column] = {
-    lazy val histogramAgg =
+    // The FileSizeHistogram computation doesn't work without whole stage codegen.
+    val avoidHistogramComputationDueToNoWholeStageCodeGen =
+      !spark.conf.get(SQLConf.WHOLESTAGE_CODEGEN_ENABLED)
+    val histogramAgg = if (
+      fileSizeHistogramEnabled && !avoidHistogramComputationDueToNoWholeStageCodeGen
+    ) {
       FileSizeHistogramUtils.histogramAggregate(coalesce(col("add.size"), lit(-1L)).expr)
+    } else {
+      lit(null).cast(FileSizeHistogram.schema)
+    }
     Map(
       // sum may return null for empty data set.
       "sizeInBytes" -> coalesce(sum(col("add.size")), lit(0L)),
@@ -159,8 +168,7 @@ trait SnapshotStateManager extends DeltaLogging { self: Snapshot =>
       "domainMetadata" -> collect_set(col("domainMetadata")),
       "metadata" -> last(col("metaData"), ignoreNulls = true),
       "protocol" -> last(col("protocol"), ignoreNulls = true),
-      "fileSizeHistogram" ->
-        (if (fileSizeHistogramEnabled) histogramAgg else lit(null).cast(FileSizeHistogram.schema))
+      "fileSizeHistogram" -> histogramAgg
     )
   }