MaxGekk commented on a change in pull request #27366: URL: https://github.com/apache/spark/pull/27366#discussion_r443202298
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/json/JsonFilters.scala ########## @@ -0,0 +1,131 @@ +/* + * 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.json + +import org.apache.spark.sql.catalyst.{InternalRow, StructFilters} +import org.apache.spark.sql.catalyst.expressions._ +import org.apache.spark.sql.internal.SQLConf +import org.apache.spark.sql.sources +import org.apache.spark.sql.types.StructType + +/** + * The class provides API for applying pushed down source filters to rows with + * struct schema parsed from JSON records. It assumes that: + * 1. reset() is called before any skipRow() calls for new row. + * 2. skipRow() can be called for any valid index of the struct fields, + * and in any order. + * + * @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. + */ +class JsonFilters(pushedFilters: Seq[sources.Filter], schema: StructType) + extends StructFilters(pushedFilters, schema) { + + /** + * Stateful JSON predicate that keeps track of its dependent references in the + * current row via `refCount`. + * + * @param predicate The predicate compiled from pushed down source filters. + * @param totalRefs The total amount of all filters references which the predicate + * compiled from. + * @param refCount The current number of predicate references in the row that have + * been not set yet. When `refCount` reaches zero, the predicate + * has all dependencies are set, and can be applied to the row. + */ + case class JsonPredicate(predicate: BasePredicate, totalRefs: Int, var refCount: Int) { + def reset(): Unit = { + refCount = totalRefs + } + } + + // Predicates compiled from the pushed down filters, and indexed by their references + // in the given schema. A predicate can occur in the array more than once if it + // has many references. For example: + // schema: i INTEGER, s STRING + // filters: IsNotNull("i"), AlwaysTrue, And(EqualTo("i", 0), StringStartsWith("s", "abc")) + // predicates: + // 0: Array(IsNotNull("i"), AlwaysTrue, And(EqualTo("i", 0), StringStartsWith("s", "abc"))) + // 1: Array(AlwaysTrue, And(EqualTo("i", 0), StringStartsWith("s", "abc"))) + private val predicates: Array[Array[JsonPredicate]] = { + val groupedPredicates = Array.fill(schema.length)(Array.empty[JsonPredicate]) + if (SQLConf.get.jsonFilterPushDown) { + val groupedByRefSet = filters + // Group filters that have the same set of references. For example: + // IsNotNull("i") -> Set("i"), AlwaysTrue -> Set(), + // And(EqualTo("i", 0), StringStartsWith("s", "abc")) -> Set("i", "s") + // By grouping filters we could avoid tracking their state of references in the + // current row separately. + .groupBy(_.references.toSet) + // Combine all filters from the same group by `And` because all filters should + // return `true` to do not skip a row. The result is compiled to a predicate. + .map { case (refSet, refsFilters) => + (refSet, JsonPredicate(toPredicate(refsFilters), refSet.size, 0)) + } + // Apply predicates w/o references like AlwaysTrue and AlwaysFalse to all fields. + // We cannot set such predicates to a particular position because skipRow() can + // be invoked for any index due to unpredictable order of JSON fields in JSON records. + val withLiterals = groupedByRefSet.map { case (refSet, pred) => + if (refSet.isEmpty) { + (schema.fields.map(_.name).toSet, pred.copy(totalRefs = 1)) + } else { + (refSet, pred) + } + } + // Build a map where key is only one field and value is seq of predicates refer to the field + // "i" -> Seq(AlwaysTrue, IsNotNull("i"), And(EqualTo("i", 0), StringStartsWith("s", "abc"))) + // "s" -> Seq(AlwaysTrue, And(EqualTo("i", 0), StringStartsWith("s", "abc"))) + val groupedByFields = withLiterals.toSeq + .flatMap { case (refSet, pred) => refSet.map((_, pred)) } + .groupBy(_._1) + // Build the final array by converting keys of `groupedByFields` to their + // indexes in the provided schema. + groupedByFields.foreach { case (fieldName, fieldPredicates) => + val fieldIndex = schema.fieldIndex(fieldName) + groupedPredicates(fieldIndex) = fieldPredicates.map(_._2).toArray + } + } + groupedPredicates + } + + /** + * Applies predicates (compiled filters) associated with the row field value + * at the position `index` only if other predicates dependencies are already + * set in the given row. + * + * @param row The row with fully or partially set values. + * @param index The index of already set value. + * @return true if at least one of applicable predicates (all dependent row values are set) + * return `false`. It returns `false` if all predicates return `true`. + */ + def skipRow(row: InternalRow, index: Int): Boolean = { + var skip = false + predicates(index).foreach { pred => + pred.refCount -= 1 Review comment: Added ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
