[SPARK-49025] Make Column implementation agnostic (#3913)

#### Which Delta project/connector is this regarding?
- [x] Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [ ] Other (fill in here)

## Description
This PR ports the changes made in SPARK-49025 to Delta.

## How was this patch tested?
Existing tests.

## Does this PR introduce _any_ user-facing changes?
No.

spark/src/main/scala-spark-3.5/shims/ColumnConversionShims.scala

@@ -0,0 +1,28 @@
+/*
+ * Copyright (2021) The Delta Lake Project Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.delta
+
+import org.apache.spark.sql.Column
+import org.apache.spark.sql.catalyst.expressions.Expression
+
+/**
+ * Conversions from a [[org.apache.spark.sql.Column]] to an
+ * [[org.apache.spark.sql.catalyst.expressions.Expression]], and vice versa.
+ */
+object ClassicColumnConversions {
+  def expression(c: Column): Expression = c.expr
+}

spark/src/main/scala-spark-master/shims/ColumnConversionShims.scala

@@ -0,0 +1,33 @@
+/*
+ * Copyright (2021) The Delta Lake Project Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.delta
+
+import org.apache.spark.sql.classic.ClassicConversions
+import org.apache.spark.sql.classic.ColumnConversions
+
+/**
+ * Conversions from a [[org.apache.spark.sql.Column]] to an
+ * [[org.apache.spark.sql.catalyst.expressions.Expression]], and vice versa.
+ *
+ * @note [[org.apache.spark.sql.internal.ExpressionUtils#expression]] is a cheap alternative for
+ *       [[org.apache.spark.sql.Column]] to [[org.apache.spark.sql.catalyst.expressions.Expression]]
+ *       conversions. However this can only be used when the produced expression is used in a Column
+ *       later on.
+ */
+object ClassicColumnConversions
+  extends ClassicConversions
+  with ColumnConversions

spark/src/main/scala/io/delta/tables/DeltaMergeBuilder.scala

@@ -20,17 +20,17 @@ import scala.collection.JavaConverters._
 import scala.collection.Map
 
 import org.apache.spark.sql.delta.{DeltaAnalysisException, PostHocResolveUpCast, PreprocessTableMerge, ResolveDeltaMergeInto}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.DeltaTableUtils.withActiveSession
 import org.apache.spark.sql.delta.DeltaViewHelper
-import org.apache.spark.sql.delta.commands.MergeIntoCommand
 import org.apache.spark.sql.delta.util.AnalysisHelper
 
 import org.apache.spark.annotation._
 import org.apache.spark.internal.Logging
 import org.apache.spark.sql._
 import org.apache.spark.sql.catalyst.ExtendedAnalysisException
 import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
-import org.apache.spark.sql.catalyst.expressions.{AttributeReference, NamedExpression}
+import org.apache.spark.sql.catalyst.expressions.AttributeReference
 import org.apache.spark.sql.catalyst.plans.logical._
 import org.apache.spark.sql.functions.expr
 import org.apache.spark.sql.internal.SQLConf

spark/src/main/scala/io/delta/tables/DeltaTable.scala

@@ -19,6 +19,7 @@ package io.delta.tables
 import scala.collection.JavaConverters._
 
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.DeltaTableUtils.withActiveSession
 import org.apache.spark.sql.delta.actions.TableFeatureProtocolUtils
 import org.apache.spark.sql.delta.catalog.DeltaTableV2

spark/src/main/scala/io/delta/tables/execution/DeltaTableOperations.scala

@@ -20,6 +20,7 @@ import scala.collection.Map
 
 import org.apache.spark.sql.catalyst.TimeTravel
 import org.apache.spark.sql.delta.{DeltaErrors, DeltaLog}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.DeltaTableUtils.withActiveSession
 import org.apache.spark.sql.delta.catalog.DeltaTableV2
 import org.apache.spark.sql.delta.commands.{DeltaGenerateCommand, DescribeDeltaDetailCommand, VacuumCommand}

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

@@ -25,6 +25,7 @@ import scala.util.Try
 import scala.util.control.NonFatal
 
 // scalastyle:off import.ordering.noEmptyLine
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{Action, CheckpointMetadata, Metadata, SidecarFile, SingleAction}
 import org.apache.spark.sql.delta.logging.DeltaLogKeys
 import org.apache.spark.sql.delta.metering.DeltaLogging

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

@@ -19,6 +19,7 @@ package org.apache.spark.sql.delta
 // scalastyle:off import.ordering.noEmptyLine
 import scala.collection.mutable
 
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{Metadata, Protocol}
 import org.apache.spark.sql.delta.commands.cdc.CDCReader
 import org.apache.spark.sql.delta.constraints.{Constraint, Constraints}

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

@@ -28,6 +28,7 @@ import scala.util.Try
 import scala.util.control.NonFatal
 
 import com.databricks.spark.util.TagDefinitions._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions._
 import org.apache.spark.sql.delta.commands.WriteIntoDelta
 import org.apache.spark.sql.delta.coordinatedcommits.CoordinatedCommitsUtils

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

@@ -19,6 +19,7 @@ package org.apache.spark.sql.delta
 // scalastyle:off import.ordering.noEmptyLine
 import java.util.Locale
 
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{Metadata, Protocol}
 import org.apache.spark.sql.delta.files.{TahoeBatchFileIndex, TahoeFileIndex}
 import org.apache.spark.sql.delta.metering.DeltaLogging

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

@@ -18,6 +18,7 @@ package org.apache.spark.sql.delta
 
 import scala.collection.mutable
 
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.metering.DeltaLogging
 import org.apache.spark.sql.delta.sources.DeltaSourceUtils._
 import org.apache.spark.sql.delta.sources.DeltaSQLConf

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

@@ -27,6 +27,7 @@ import scala.collection.mutable.{ArrayBuffer, HashSet}
 import scala.util.control.NonFatal
 
 import com.databricks.spark.util.TagDefinitions.TAG_LOG_STORE_CLASS
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.DeltaOperations.{ChangeColumn, CreateTable, Operation, ReplaceColumns, ReplaceTable, UpdateSchema}
 import org.apache.spark.sql.delta.RowId.RowTrackingMetadataDomain
 import org.apache.spark.sql.delta.actions._

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

@@ -28,6 +28,7 @@ import scala.collection.mutable
 import scala.util.control.NonFatal
 
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.commands.DeletionVectorUtils
 import org.apache.spark.sql.delta.sources.DeltaSQLConf
 import org.apache.spark.sql.delta.util.{DeltaFileOperations, JsonUtils, Utils => DeltaUtils}

spark/src/main/scala/org/apache/spark/sql/delta/commands/DMLWithDeletionVectorsHelper.scala

@@ -22,6 +22,7 @@ import scala.collection.generic.Sizing
 
 import org.apache.spark.sql.catalyst.expressions.aggregation.BitmapAggregator
 import org.apache.spark.sql.delta.{DeltaLog, DeltaParquetFileFormat, OptimisticTransaction, Snapshot}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.DeltaParquetFileFormat._
 import org.apache.spark.sql.delta.actions.{AddFile, DeletionVectorDescriptor, FileAction}
 import org.apache.spark.sql.delta.deletionvectors.{RoaringBitmapArray, RoaringBitmapArrayFormat, StoredBitmap}

spark/src/main/scala/org/apache/spark/sql/delta/commands/DeleteCommand.scala

@@ -20,6 +20,7 @@ import java.util.concurrent.TimeUnit
 
 import org.apache.spark.sql.delta.metric.IncrementMetric
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{Action, AddCDCFile, AddFile, FileAction}
 import org.apache.spark.sql.delta.commands.DeleteCommand.{rewritingFilesMsg, FINDING_TOUCHED_FILES_MSG}
 import org.apache.spark.sql.delta.commands.MergeIntoCommandBase.totalBytesAndDistinctPartitionValues

spark/src/main/scala/org/apache/spark/sql/delta/commands/UpdateCommand.scala

@@ -21,6 +21,7 @@ import java.util.concurrent.TimeUnit
 
 import org.apache.spark.sql.delta.metric.IncrementMetric
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{AddCDCFile, AddFile, FileAction}
 import org.apache.spark.sql.delta.commands.cdc.CDCReader.{CDC_TYPE_COLUMN_NAME, CDC_TYPE_NOT_CDC, CDC_TYPE_UPDATE_POSTIMAGE, CDC_TYPE_UPDATE_PREIMAGE}
 import org.apache.spark.sql.delta.files.{TahoeBatchFileIndex, TahoeFileIndex}

spark/src/main/scala/org/apache/spark/sql/delta/commands/WriteIntoDelta.scala

@@ -20,6 +20,7 @@ import scala.collection.mutable
 
 // scalastyle:off import.ordering.noEmptyLine
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions._
 import org.apache.spark.sql.delta.commands.DMLUtils.TaggedCommitData
 import org.apache.spark.sql.delta.commands.cdc.CDCReader

spark/src/main/scala/org/apache/spark/sql/delta/commands/alterDeltaTableCommands.scala

@@ -25,6 +25,7 @@ import scala.util.control.NonFatal
 import org.apache.spark.sql.delta.skipping.clustering.ClusteredTableUtils
 import org.apache.spark.sql.delta.skipping.clustering.ClusteringColumnInfo
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.Protocol
 import org.apache.spark.sql.delta.actions.TableFeatureProtocolUtils
 import org.apache.spark.sql.delta.catalog.DeltaTableV2

spark/src/main/scala/org/apache/spark/sql/delta/commands/cdc/CDCReader.scala

@@ -22,6 +22,7 @@ import scala.collection.mutable.{ListBuffer, Map => MutableMap}
 import scala.util.Try
 
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions._
 import org.apache.spark.sql.delta.commands.DeletionVectorUtils
 import org.apache.spark.sql.delta.deletionvectors.{RoaringBitmapArray, RoaringBitmapArrayFormat}

spark/src/main/scala/org/apache/spark/sql/delta/commands/merge/ClassicMergeExecutor.scala

@@ -19,6 +19,7 @@ package org.apache.spark.sql.delta.commands.merge
 import scala.collection.JavaConverters._
 
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{AddCDCFile, AddFile, FileAction}
 import org.apache.spark.sql.delta.commands.{DeletionVectorBitmapGenerator, DMLWithDeletionVectorsHelper, MergeIntoCommandBase}
 import org.apache.spark.sql.delta.commands.cdc.CDCReader.{CDC_TYPE_COLUMN_NAME, CDC_TYPE_NOT_CDC}
@@ -246,7 +247,7 @@ trait ClassicMergeExecutor extends MergeOutputGeneration {
    */
   protected def generateFilterForModifiedRows(): Expression = {
     val matchedExpression = if (matchedClauses.nonEmpty) {
-      And(Column(condition).expr, clauseDisjunction(matchedClauses))
+      And(condition, clauseDisjunction(matchedClauses))
     } else {
       Literal.FalseLiteral
     }

spark/src/main/scala/org/apache/spark/sql/delta/commands/merge/InsertOnlyMergeExecutor.scala

@@ -18,6 +18,7 @@ package org.apache.spark.sql.delta.commands.merge
 
 import org.apache.spark.sql.delta.metric.IncrementMetric
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{AddFile, FileAction}
 import org.apache.spark.sql.delta.commands.MergeIntoCommandBase
 

spark/src/main/scala/org/apache/spark/sql/delta/commands/merge/MergeOutputGeneration.scala

@@ -19,6 +19,7 @@ package org.apache.spark.sql.delta.commands.merge
 import scala.collection.mutable
 
 import org.apache.spark.sql.delta.{RowCommitVersion, RowId}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.commands.MergeIntoCommandBase
 import org.apache.spark.sql.delta.commands.cdc.CDCReader
 
@@ -164,8 +165,8 @@ trait MergeOutputGeneration { self: MergeIntoCommandBase =>
     // That is, conditionally invokes them based on whether there was a match in the outer join.
 
     // Predicates to check whether there was a match in the full outer join.
-    val ifSourceRowNull = col(SOURCE_ROW_PRESENT_COL).isNull.expr
-    val ifTargetRowNull = col(TARGET_ROW_PRESENT_COL).isNull.expr
+    val ifSourceRowNull = expression(col(SOURCE_ROW_PRESENT_COL).isNull)
+    val ifTargetRowNull = expression(col(TARGET_ROW_PRESENT_COL).isNull)
 
     val outputCols = targetWriteColNames.zipWithIndex.map { case (name, i) =>
       // Coupled with the clause conditions, the resultant possibly-nested CaseWhens can
@@ -213,7 +214,8 @@ trait MergeOutputGeneration { self: MergeIntoCommandBase =>
         Column(Alias(caseWhen, name)())
       }
     }
-    logDebug("writeAllChanges: join output expressions\n\t" + seqToString(outputCols.map(_.expr)))
+    logDebug("writeAllChanges: join output expressions\n\t" + seqToString(
+      outputCols.map(expression)))
     outputCols
   }.toIndexedSeq
 
@@ -421,36 +423,36 @@ trait MergeOutputGeneration { self: MergeIntoCommandBase =>
 
     val cdcTypeCol = outputCols.last
     val cdcArray = Column(CaseWhen(Seq(
-      EqualNullSafe(cdcTypeCol.expr, Literal(CDC_TYPE_INSERT)) -> array(
-        struct(outputCols: _*)).expr,
+      EqualNullSafe(expression(cdcTypeCol), Literal(CDC_TYPE_INSERT)) -> expression(array(
+        struct(outputCols: _*))),
 
-      EqualNullSafe(cdcTypeCol.expr, Literal(CDC_TYPE_UPDATE_POSTIMAGE)) -> array(
+      EqualNullSafe(expression(cdcTypeCol), Literal(CDC_TYPE_UPDATE_POSTIMAGE)) -> expression(array(
         struct(updatePreimageCdcOutput: _*),
-        struct(outputCols: _*)).expr,
+        struct(outputCols: _*))),
 
-      EqualNullSafe(cdcTypeCol.expr, CDC_TYPE_DELETE) -> array(
-        struct(deleteCdcOutput: _*)).expr),
+      EqualNullSafe(expression(cdcTypeCol), CDC_TYPE_DELETE) -> expression(array(
+        struct(deleteCdcOutput: _*)))),
 
       // If none of the CDC cases apply (true for purely rewritten target rows, dropped source
       // rows, etc.) just stick to the normal output.
-      array(struct(mainDataOutput: _*)).expr
+      expression(array(struct(mainDataOutput: _*)))
     ))
 
     val cdcToMainDataArray = Column(If(
       Or(
-        EqualNullSafe(col(s"packedCdc.$CDC_TYPE_COLUMN_NAME").expr,
+        EqualNullSafe(expression(col(s"packedCdc.$CDC_TYPE_COLUMN_NAME")),
           Literal(CDC_TYPE_INSERT)),
-        EqualNullSafe(col(s"packedCdc.$CDC_TYPE_COLUMN_NAME").expr,
+        EqualNullSafe(expression(col(s"packedCdc.$CDC_TYPE_COLUMN_NAME")),
           Literal(CDC_TYPE_UPDATE_POSTIMAGE))),
-      array(
+      expression(array(
         col("packedCdc"),
         struct(
           outputColNames
             .dropRight(1)
             .map { n => col(s"packedCdc.`$n`") }
             :+ Column(CDC_TYPE_NOT_CDC).as(CDC_TYPE_COLUMN_NAME): _*)
-      ).expr,
-      array(col("packedCdc")).expr
+      )),
+      expression(array(col("packedCdc")))
     ))
 
     if (deduplicateDeletes.enabled) {

spark/src/main/scala/org/apache/spark/sql/delta/hooks/GenerateSymlinkManifest.scala

@@ -20,6 +20,7 @@ package org.apache.spark.sql.delta.hooks
 import java.net.URI
 
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions._
 import org.apache.spark.sql.delta.commands.DeletionVectorUtils.isTableDVFree
 import org.apache.spark.sql.delta.logging.DeltaLogKeys

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

@@ -16,6 +16,7 @@
 
 package org.apache.spark.sql.delta
 
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.OptimizablePartitionExpression._
 
 import org.apache.spark.sql.Column

spark/src/main/scala/org/apache/spark/sql/delta/schema/SchemaUtils.scala

@@ -22,6 +22,7 @@ import scala.util.control.NonFatal
 
 import org.apache.spark.sql.delta.{DeltaAnalysisException, DeltaColumnMappingMode, DeltaErrors, DeltaLog, GeneratedColumn, NoMapping, TypeWidening, TypeWideningMode}
 import org.apache.spark.sql.delta.{RowCommitVersion, RowId}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.Protocol
 import org.apache.spark.sql.delta.commands.cdc.CDCReader
 import org.apache.spark.sql.delta.logging.DeltaLogKeys

spark/src/main/scala/org/apache/spark/sql/delta/skipping/MultiDimClusteringFunctions.scala

@@ -18,6 +18,7 @@ package org.apache.spark.sql.delta.skipping
 
 // scalastyle:off import.ordering.noEmptyLine
 import org.apache.spark.sql.delta.expressions.{HilbertByteArrayIndex, HilbertLongIndex, InterleaveBits, RangePartitionId}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 
 import org.apache.spark.SparkException
 import org.apache.spark.sql.Column
@@ -37,7 +38,7 @@ object MultiDimClusteringFunctions {
    * partition range ids as (0, 0, 1, 1, 2, 2).
    */
   def range_partition_id(col: Column, numPartitions: Int): Column = withExpr {
-    RangePartitionId(col.expr, numPartitions)
+    RangePartitionId(expression(col), numPartitions)
   }
 
   /**
@@ -54,7 +55,7 @@ object MultiDimClusteringFunctions {
    * @note Only supports input expressions of type Int for now.
    */
   def interleave_bits(cols: Column*): Column = withExpr {
-    InterleaveBits(cols.map(_.expr))
+    InterleaveBits(cols.map(expression))
   }
 
   // scalastyle:off line.size.limit
@@ -73,9 +74,9 @@ object MultiDimClusteringFunctions {
     }
     val hilbertBits = cols.length * numBits
     if (hilbertBits < 64) {
-      HilbertLongIndex(numBits, cols.map(_.expr))
+      HilbertLongIndex(numBits, cols.map(expression))
     } else {
-      Cast(HilbertByteArrayIndex(numBits, cols.map(_.expr)), StringType)
+      Cast(HilbertByteArrayIndex(numBits, cols.map(expression)), StringType)
     }
   }
 }

spark/src/main/scala/org/apache/spark/sql/delta/sources/DeltaSink.scala

@@ -19,6 +19,7 @@ package org.apache.spark.sql.delta.sources
 import java.util.concurrent.ConcurrentHashMap
 
 import org.apache.spark.sql.delta._
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.DeltaOperations.StreamingUpdate
 import org.apache.spark.sql.delta.actions.{FileAction, Metadata, Protocol, SetTransaction}
 import org.apache.spark.sql.delta.logging.DeltaLogKeys

spark/src/main/scala/org/apache/spark/sql/delta/stats/DataSkippingPredicateBuilder.scala

@@ -16,6 +16,7 @@
 
 package org.apache.spark.sql.delta.stats
 
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.stats.DeltaStatistics.{MAX, MIN}
 
 import org.apache.spark.sql.Column

spark/src/main/scala/org/apache/spark/sql/delta/stats/DataSkippingReader.scala

@@ -23,6 +23,7 @@ import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.sql.delta.skipping.clustering.{ClusteredTableUtils, ClusteringColumnInfo}
 import org.apache.spark.sql.delta.{DeltaColumnMapping, DeltaLog, DeltaTableUtils}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 import org.apache.spark.sql.delta.actions.{AddFile, Metadata}
 import org.apache.spark.sql.delta.implicits._
 import org.apache.spark.sql.delta.metering.DeltaLogging

spark/src/main/scala/org/apache/spark/sql/delta/stats/DeletedRecordCountsHistogramUtils.scala

@@ -17,6 +17,7 @@
 package org.apache.spark.sql.delta.stats
 
 import org.apache.spark.sql.delta.{DeltaErrors, DeltaUDF}
+import org.apache.spark.sql.delta.ClassicColumnConversions._
 
 import org.apache.spark.sql.Column
 import org.apache.spark.sql.catalyst.InternalRow