rdblue commented on a change in pull request #1738:
URL: https://github.com/apache/iceberg/pull/1738#discussion_r519073827



##########
File path: 
spark3-extensions/src/main/scala/org/apache/spark/sql/catalyst/optimizer/RewriteDelete.scala
##########
@@ -0,0 +1,160 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.catalyst.optimizer
+
+import java.util.UUID
+import org.apache.spark.sql.{sources, AnalysisException}
+import org.apache.spark.sql.catalyst.analysis.Resolver
+import org.apache.spark.sql.catalyst.expressions.{Alias, Attribute, 
AttributeReference, EqualNullSafe, Expression, InputFileName, Literal, Not, 
PredicateHelper, SubqueryExpression}
+import org.apache.spark.sql.catalyst.expressions.Literal.FalseLiteral
+import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, 
DeleteFromTable, DynamicFileFilter, Filter, LocalRelation, LogicalPlan, 
OverwriteFiles, Project}
+import org.apache.spark.sql.catalyst.rules.Rule
+import org.apache.spark.sql.connector.catalog.{SupportsMetadataOnlyDeletes, 
Table}
+import org.apache.spark.sql.connector.write.{LogicalWriteInfo, 
LogicalWriteInfoImpl, RowLevelOperationsBuilder, 
SupportsPushDownRowLevelFilters}
+import org.apache.spark.sql.execution.datasources.DataSourceStrategy
+import org.apache.spark.sql.execution.datasources.v2.{DataSourceV2Relation, 
DataSourceV2ScanRelation}
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.types.{BooleanType, StructType}
+import org.apache.spark.sql.util.CaseInsensitiveStringMap
+
+// TODO: should be part of early scan push down after the delete condition is 
optimized
+object RewriteDelete extends Rule[LogicalPlan] with PredicateHelper {
+
+  import 
org.apache.spark.sql.execution.datasources.v2.ExtendedDataSourceV2Implicits._
+
+  private val FILE_NAME_COL = "_file"
+
+  override def apply(plan: LogicalPlan): LogicalPlan = plan resolveOperators {
+    // no need to execute this delete as the condition is false
+    case DeleteFromTable(_, Some(FalseLiteral)) =>
+      LocalRelation()
+
+    // don't rewrite deletes that can be answered using metadata only 
operations
+    case d @ DeleteFromTable(r: DataSourceV2Relation, Some(cond)) if 
isMetadataOnlyOperation(r, cond) =>
+      d
+
+    // rewrite all operations that require reading the table to delete records
+    case DeleteFromTable(r: DataSourceV2Relation, Some(cond)) =>
+      // TODO: do a switch based on whether we get BatchWrite or 
DeltaBatchWrite
+      val writeInfo = newWriteInfo(r.schema)
+      val builder = 
r.table.asRowLevelModifiable.newRowLevelOperationsBuilder(writeInfo)
+
+      pushDownFilters(builder, cond, r.output)
+
+      val scan = builder.buildScan()
+      val scanRelation = DataSourceV2ScanRelation(r.table, scan, r.output)
+      val filterPlan = buildFilterPlan(cond, scanRelation)
+
+      val batchWrite = builder.buildBatchWrite()
+      // TODO: group by something so that we can write back
+      // Option 1: repartition/sort by partition values
+      // Option 2: repartition by _file and local sort by partition values 
(how to deal with 1 GB files?)

Review comment:
       If this is currently a one-stage plan (other than dynamic filtering) 
then I'd say let's not add a shuffle. That way, the source can create a 1-to-1 
file replacement. Later, we can use `RequiresDistributionAndOrdering` to make 
this customizable.




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