spark ReplaceNullWithFalseInPredicate 源码

spark ReplaceNullWithFalseInPredicate 代码

文件路径：/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/ReplaceNullWithFalseInPredicate.scala

/*
 * 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 org.apache.spark.sql.catalyst.expressions.{And, ArrayExists, ArrayFilter, CaseWhen, EqualNullSafe, Expression, If, In, InSet, LambdaFunction, Literal, MapFilter, Not, Or}
import org.apache.spark.sql.catalyst.expressions.Literal.{FalseLiteral, TrueLiteral}
import org.apache.spark.sql.catalyst.plans.logical.{DeleteAction, DeleteFromTable, Filter, InsertAction, InsertStarAction, Join, LogicalPlan, MergeAction, MergeIntoTable, ReplaceData, UpdateAction, UpdateStarAction, UpdateTable}
import org.apache.spark.sql.catalyst.rules.Rule
import org.apache.spark.sql.catalyst.trees.TreePattern.{INSET, NULL_LITERAL, TRUE_OR_FALSE_LITERAL}
import org.apache.spark.sql.types.BooleanType
import org.apache.spark.util.Utils


/**
 * A rule that replaces `Literal(null, BooleanType)` with `FalseLiteral`, if possible, in the search
 * condition of the WHERE/HAVING/ON(JOIN) clauses, which contain an implicit Boolean operator
 * "(search condition) = TRUE". The replacement is only valid when `Literal(null, BooleanType)` is
 * semantically equivalent to `FalseLiteral` when evaluating the whole search condition.
 *
 * Please note that FALSE and NULL are not exchangeable in most cases, when the search condition
 * contains NOT and NULL-tolerant expressions. Thus, the rule is very conservative and applicable
 * in very limited cases.
 *
 * For example, `Filter(Literal(null, BooleanType))` is equal to `Filter(FalseLiteral)`.
 *
 * Another example containing branches is `Filter(If(cond, FalseLiteral, Literal(null, _)))`;
 * this can be optimized to `Filter(If(cond, FalseLiteral, FalseLiteral))`, and eventually
 * `Filter(FalseLiteral)`.
 *
 * Moreover, this rule also transforms predicates in all [[If]] expressions as well as branch
 * conditions in all [[CaseWhen]] expressions, even if they are not part of the search conditions.
 *
 * For example, `Project(If(And(cond, Literal(null)), Literal(1), Literal(2)))` can be simplified
 * into `Project(Literal(2))`.
 */
object ReplaceNullWithFalseInPredicate extends Rule[LogicalPlan] {

  def apply(plan: LogicalPlan): LogicalPlan = plan.transformWithPruning(
    _.containsAnyPattern(NULL_LITERAL, TRUE_OR_FALSE_LITERAL, INSET), ruleId) {
    case f @ Filter(cond, _) => f.copy(condition = replaceNullWithFalse(cond))
    case j @ Join(_, _, _, Some(cond), _) => j.copy(condition = Some(replaceNullWithFalse(cond)))
    case rd @ ReplaceData(_, cond, _, _, _) => rd.copy(condition = replaceNullWithFalse(cond))
    case d @ DeleteFromTable(_, cond) => d.copy(condition = replaceNullWithFalse(cond))
    case u @ UpdateTable(_, _, Some(cond)) => u.copy(condition = Some(replaceNullWithFalse(cond)))
    case m @ MergeIntoTable(_, _, mergeCond, matchedActions, notMatchedActions) =>
      m.copy(
        mergeCondition = replaceNullWithFalse(mergeCond),
        matchedActions = replaceNullWithFalse(matchedActions),
        notMatchedActions = replaceNullWithFalse(notMatchedActions))
    case p: LogicalPlan => p.transformExpressionsWithPruning(
      _.containsAnyPattern(NULL_LITERAL, TRUE_OR_FALSE_LITERAL), ruleId) {
      // For `EqualNullSafe` with a `TrueLiteral`, whether the other side is null or false has no
      // difference, as `null <=> true` and `false <=> true` both return false.
      case EqualNullSafe(left, TrueLiteral) =>
        EqualNullSafe(replaceNullWithFalse(left), TrueLiteral)
      case EqualNullSafe(TrueLiteral, right) =>
        EqualNullSafe(TrueLiteral, replaceNullWithFalse(right))
      case i @ If(pred, _, _) => i.copy(predicate = replaceNullWithFalse(pred))
      case cw @ CaseWhen(branches, _) =>
        val newBranches = branches.map { case (cond, value) =>
          replaceNullWithFalse(cond) -> value
        }
        cw.copy(branches = newBranches)
      case af @ ArrayFilter(_, lf @ LambdaFunction(func, _, _)) =>
        val newLambda = lf.copy(function = replaceNullWithFalse(func))
        af.copy(function = newLambda)
      case ae @ ArrayExists(_, lf @ LambdaFunction(func, _, _), false) =>
        val newLambda = lf.copy(function = replaceNullWithFalse(func))
        ae.copy(function = newLambda)
      case mf @ MapFilter(_, lf @ LambdaFunction(func, _, _)) =>
        val newLambda = lf.copy(function = replaceNullWithFalse(func))
        mf.copy(function = newLambda)
    }
  }

  /**
   * Recursively traverse the Boolean-type expression to replace
   * `Literal(null, BooleanType)` with `FalseLiteral`, if possible.
   *
   * Note that `transformExpressionsDown` can not be used here as we must stop as soon as we hit
   * an expression that is not [[CaseWhen]], [[If]], [[And]], [[Or]] or
   * `Literal(null, BooleanType)`.
   */
  private def replaceNullWithFalse(e: Expression): Expression = e match {
    case Literal(null, BooleanType) =>
      FalseLiteral
    // In SQL, the `Not(IN)` expression evaluates as follows:
    // `NULL not in (1)` -> NULL
    // `NULL not in (1, NULL)` -> NULL
    // `1 not in (1, NULL)` -> false
    // `1 not in (2, NULL)` -> NULL
    // In predicate, NULL is equal to false, so we can simplify them to false directly.
    case Not(In(value, list)) if (value +: list).exists(isNullLiteral) =>
      FalseLiteral
    case Not(InSet(value, list)) if isNullLiteral(value) || list.contains(null) =>
      FalseLiteral

    case And(left, right) =>
      And(replaceNullWithFalse(left), replaceNullWithFalse(right))
    case Or(left, right) =>
      Or(replaceNullWithFalse(left), replaceNullWithFalse(right))
    case cw: CaseWhen if cw.dataType == BooleanType =>
      val newBranches = cw.branches.map { case (cond, value) =>
        replaceNullWithFalse(cond) -> replaceNullWithFalse(value)
      }
      val newElseValue = cw.elseValue.map(replaceNullWithFalse).getOrElse(FalseLiteral)
      CaseWhen(newBranches, newElseValue)
    case i @ If(pred, trueVal, falseVal) if i.dataType == BooleanType =>
      If(replaceNullWithFalse(pred), replaceNullWithFalse(trueVal), replaceNullWithFalse(falseVal))
    case e if e.dataType == BooleanType =>
      e
    case e =>
      val message = "Expected a Boolean type expression in replaceNullWithFalse, " +
        s"but got the type `${e.dataType.catalogString}` in `${e.sql}`."
      if (Utils.isTesting) {
        throw new IllegalArgumentException(message)
      } else {
        logWarning(message)
        e
      }
  }

  private def replaceNullWithFalse(mergeActions: Seq[MergeAction]): Seq[MergeAction] = {
    mergeActions.map {
      case u @ UpdateAction(Some(cond), _) => u.copy(condition = Some(replaceNullWithFalse(cond)))
      case u @ UpdateStarAction(Some(cond)) => u.copy(condition = Some(replaceNullWithFalse(cond)))
      case d @ DeleteAction(Some(cond)) => d.copy(condition = Some(replaceNullWithFalse(cond)))
      case i @ InsertAction(Some(cond), _) => i.copy(condition = Some(replaceNullWithFalse(cond)))
      case i @ InsertStarAction(Some(cond)) => i.copy(condition = Some(replaceNullWithFalse(cond)))
      case other => other
    }
  }

  private def isNullLiteral(e: Expression): Boolean = e match {
    case Literal(null, _) => true
    case _ => false
  }
}

相关信息

spark 源码目录

相关文章

spark ComplexTypes 源码

spark CostBasedJoinReorder 源码

spark DecorrelateInnerQuery 源码

spark EliminateResolvedHint 源码

spark InjectRuntimeFilter 源码

spark InlineCTE 源码

spark LimitPushDownThroughWindow 源码

spark MergeScalarSubqueries 源码

spark NestedColumnAliasing 源码

spark NormalizeFloatingNumbers 源码