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From GitBox <...@apache.org>
Subject [GitHub] [spark] MaxGekk commented on a change in pull request #27366: [SPARK-30648][SQL] Support filters pushdown in JSON datasource
Date Tue, 23 Jun 2020 06:30:55 GMT

MaxGekk commented on a change in pull request #27366:
URL: https://github.com/apache/spark/pull/27366#discussion_r443990454



##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/StructFilters.scala
##########
@@ -0,0 +1,161 @@
+/*
+ * 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
+
+import scala.util.Try
+
+import org.apache.spark.sql.catalyst.StructFilters._
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.sources
+import org.apache.spark.sql.types.{BooleanType, StructType}
+
+/**
+ * The class provides API for applying pushed down filters to partially or
+ * fully set internal rows that have the struct schema.
+ *
+ * @param pushedFilters The pushed down source filters. The filters should refer to
+ *                      the fields of the provided schema.
+ * @param schema The required schema of records from datasource files.
+ */
+abstract class StructFilters(pushedFilters: Seq[sources.Filter], schema: StructType) {
+
+  protected val filters = pushedFilters.filter(checkFilterRefs(_, schema.fieldNames.toSet))
+
+  /**
+   * Applies pushed down source filters to the given row assuming that
+   * value at `index` has been already set.
+   *
+   * @param row The row with fully or partially set values.
+   * @param index The index of already set value.
+   * @return true if currently processed row can be skipped otherwise false.
+   */
+  def skipRow(row: InternalRow, index: Int): Boolean
+
+  /**
+   * Resets states of pushed down filters. The method must be called before
+   * precessing any new row otherwise skipRow() may return wrong result.
+   */
+  def reset(): Unit
+
+  /**
+   * Compiles source filters to a predicate.
+   */
+  def toPredicate(filters: Seq[sources.Filter]): BasePredicate = {
+    val reducedExpr = filters
+      .sortBy(_.references.length)
+      .flatMap(filterToExpression(_, toRef))
+      .reduce(And)
+    Predicate.create(reducedExpr)
+  }
+
+  // Finds a filter attribute in the schema and converts it to a `BoundReference`
+  def toRef(attr: String): Option[BoundReference] = {
+    schema.getFieldIndex(attr).map { index =>
+      val field = schema(index)
+      BoundReference(schema.fieldIndex(attr), field.dataType, field.nullable)

Review comment:
       Right, I will replace it by `index`.




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