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ReplaceNullWithFalseInPredicate.scala
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ReplaceNullWithFalseInPredicate.scala
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/*
* 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.SparkIllegalArgumentException
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, WriteDelta}
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, _, _, groupFilterCond, _) =>
val newCond = replaceNullWithFalse(cond)
val newGroupFilterCond = groupFilterCond.map(replaceNullWithFalse)
rd.copy(condition = newCond, groupFilterCondition = newGroupFilterCond)
case wd @ WriteDelta(_, cond, _, _, _, _) => wd.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 =>
m.copy(
mergeCondition = replaceNullWithFalse(m.mergeCondition),
matchedActions = replaceNullWithFalse(m.matchedActions),
notMatchedActions = replaceNullWithFalse(m.notMatchedActions),
notMatchedBySourceActions = replaceNullWithFalse(m.notMatchedBySourceActions))
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 =>
if (Utils.isTesting) {
throw new SparkIllegalArgumentException(
errorClass = "_LEGACY_ERROR_TEMP_3215",
messageParameters = Map(
"dataType" -> e.dataType.catalogString,
"expr" -> e.sql))
} else {
val message = "Expected a Boolean type expression in replaceNullWithFalse, " +
s"but got the type `${e.dataType.catalogString}` in `${e.sql}`."
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
}
}