[GitHub] [iceberg] rdblue commented on a change in pull request #3983: Spark: Spark3 ZOrder Rewrite Strategy

[GitBox <gi...@apache.org>]

rdblue commented on a change in pull request #3983:
URL: https://github.com/apache/iceberg/pull/3983#discussion_r805418354



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File path: spark/v3.2/spark/src/main/java/org/apache/iceberg/spark/actions/Spark3ZOrderStrategy.java
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@@ -0,0 +1,302 @@
+/*
+ * 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.iceberg.spark.actions;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Set;
+import java.util.UUID;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.apache.iceberg.DataFile;
+import org.apache.iceberg.FileScanTask;
+import org.apache.iceberg.NullOrder;
+import org.apache.iceberg.PartitionField;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.SortDirection;
+import org.apache.iceberg.Table;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.spark.FileRewriteCoordinator;
+import org.apache.iceberg.spark.FileScanTaskSetManager;
+import org.apache.iceberg.spark.SparkDistributionAndOrderingUtil;
+import org.apache.iceberg.spark.SparkReadOptions;
+import org.apache.iceberg.spark.SparkWriteOptions;
+import org.apache.iceberg.types.Types;
+import org.apache.iceberg.types.Types.NestedField;
+import org.apache.iceberg.util.SortOrderUtil;
+import org.apache.iceberg.util.ZOrderByteUtils;
+import org.apache.spark.sql.Column;
+import org.apache.spark.sql.Dataset;
+import org.apache.spark.sql.Row;
+import org.apache.spark.sql.SparkSession;
+import org.apache.spark.sql.catalyst.plans.logical.LogicalPlan;
+import org.apache.spark.sql.connector.distributions.Distribution;
+import org.apache.spark.sql.connector.distributions.Distributions;
+import org.apache.spark.sql.connector.expressions.SortOrder;
+import org.apache.spark.sql.expressions.UserDefinedFunction;
+import org.apache.spark.sql.functions;
+import org.apache.spark.sql.internal.SQLConf;
+import org.apache.spark.sql.types.BinaryType;
+import org.apache.spark.sql.types.BooleanType;
+import org.apache.spark.sql.types.ByteType;
+import org.apache.spark.sql.types.DataType;
+import org.apache.spark.sql.types.DataTypes;
+import org.apache.spark.sql.types.DateType;
+import org.apache.spark.sql.types.DoubleType;
+import org.apache.spark.sql.types.FloatType;
+import org.apache.spark.sql.types.IntegerType;
+import org.apache.spark.sql.types.LongType;
+import org.apache.spark.sql.types.ShortType;
+import org.apache.spark.sql.types.StringType;
+import org.apache.spark.sql.types.StructField;
+import org.apache.spark.sql.types.TimestampType;
+import scala.collection.Seq;
+
+public class Spark3ZOrderStrategy extends Spark3SortStrategy {
+
+  private static final String Z_COLUMN = "ICEZVALUE";
+  private static final Schema Z_SCHEMA = new Schema(NestedField.required(0, Z_COLUMN, Types.BinaryType.get()));
+  private static final org.apache.iceberg.SortOrder Z_SORT_ORDER = org.apache.iceberg.SortOrder.builderFor(Z_SCHEMA)
+      .sortBy(Z_COLUMN, SortDirection.ASC, NullOrder.NULLS_LAST)
+      .build();
+  private static final int STRING_KEY_LENGTH = 60;
+
+  private final List<String> zOrderColNames;
+  private final FileScanTaskSetManager manager = FileScanTaskSetManager.get();
+  private final FileRewriteCoordinator rewriteCoordinator = FileRewriteCoordinator.get();
+
+  public Spark3ZOrderStrategy(Table table, SparkSession spark, List<String> zOrderColNames) {
+    super(table, spark);
+
+    Stream<String> identityPartitionColumns = table.spec().fields().stream()
+        .filter(f -> f.transform().isIdentity())
+        .map(PartitionField::name);
+    List<String> partZOrderCols = identityPartitionColumns
+        .filter(zOrderColNames::contains)
+        .collect(Collectors.toList());
+    Preconditions.checkArgument(
+        partZOrderCols.isEmpty(),
+        "Cannot ZOrder on an Identity partition column as these values are constant within a partition, " +
+            "ZOrdering requested on %s",
+        partZOrderCols);

Review comment:
       What do you think about simply removing the column because the order is identical without it? If I want to use `order by zorder(col1, col2)` but I know `col1` is always a constant (as it is for a file in an identity partition) then it's equivalent to `order by col2`.
   
   I think I'd prefer to produce an equivalent, rather than failing.




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