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[SPARK-25714] Fix Null Handling in the Optimizer rule BooleanSimplification #22702

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[SPARK-25714] Fix Null Handling in the Optimizer rule BooleanSimplification #22702

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gatorsmile Oct 11, 2018
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gatorsmile Oct 12, 2018
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18 changes: 9 additions & 9 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
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Expand Up @@ -276,15 +276,15 @@ object BooleanSimplification extends Rule[LogicalPlan] with PredicateHelper {
case a And b if a.semanticEquals(b) => a
case a Or b if a.semanticEquals(b) => a

case a And (b Or c) if Not(a).semanticEquals(b) => And(a, c)
case a And (b Or c) if Not(a).semanticEquals(c) => And(a, b)
case (a Or b) And c if a.semanticEquals(Not(c)) => And(b, c)
case (a Or b) And c if b.semanticEquals(Not(c)) => And(a, c)

case a Or (b And c) if Not(a).semanticEquals(b) => Or(a, c)
case a Or (b And c) if Not(a).semanticEquals(c) => Or(a, b)
case (a And b) Or c if a.semanticEquals(Not(c)) => Or(b, c)
case (a And b) Or c if b.semanticEquals(Not(c)) => Or(a, c)
case a And (b Or c) if !a.nullable && Not(a).semanticEquals(b) => And(a, c)

@cloud-fan cloud-fan Oct 12, 2018 •
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assuming a is null, then b is also null.
If c is null: a And (b Or c) -> null, And(a, c) -> null
If c is true: a And (b Or c) -> null, And(a, c) -> null
if c is false: a And (b Or c) -> null, And(a, c) -> false

So yes this is a bug, and we should rewrite it to If(IsNull(a), null, And(a, c)), because if a is null, the result is always null.

@cloud-fan cloud-fan Oct 12, 2018

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Since this is complicated, shall we put a comment to explain it?

@cloud-fan cloud-fan Oct 12, 2018

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after more thoughts, a And (b Or c) should be better than If(IsNull(a), null, And(a, c)), as it's more likely to get pushed down to data source, so the changes here LGTM

case a And (b Or c) if !a.nullable && Not(a).semanticEquals(c) => And(a, b)
case (a Or b) And c if !a.nullable && a.semanticEquals(Not(c)) => And(b, c)
case (a Or b) And c if !b.nullable && b.semanticEquals(Not(c)) => And(a, c)

case a Or (b And c) if !a.nullable && Not(a).semanticEquals(b) => Or(a, c)

@mgaido91 mgaido91 Oct 12, 2018

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these shouldn't be a problem, since if a is true, then a Or b is true, regardless of b's value/nullability, isn't it?

@cloud-fan cloud-fan Oct 12, 2018

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the problem is when a is null, c is true

@mgaido91 mgaido91 Oct 12, 2018

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I see now, sorry. Thanks.

@mgaido91 mgaido91 Oct 12, 2018

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Sorry, it is the other case where the change is not needed, right?
a And (b Or c) -> And(a, c) when a is null, And(a, c) returns null (I got a bit confused earlier, sorry).

@cloud-fan cloud-fan Oct 12, 2018

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when a is null, And(a, c) returns null

This is not always the case, null && false is false

@mgaido91 mgaido91 Oct 12, 2018

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oh, yes you're right, this might be a problem indeed if the expression is inside a not. Sorry, thanks.

case a Or (b And c) if !a.nullable && Not(a).semanticEquals(c) => Or(a, b)
case (a And b) Or c if !a.nullable && a.semanticEquals(Not(c)) => Or(b, c)
case (a And b) Or c if !b.nullable && b.semanticEquals(Not(c)) => Or(a, c)

// Common factor elimination for conjunction
case and @ (left And right) =>
Expand Down
111 changes: 87 additions & 24 deletions ...t/src/test/scala/org/apache/spark/sql/catalyst/optimizer/BooleanSimplificationSuite.scala
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Expand Up @@ -29,7 +29,7 @@ import org.apache.spark.sql.catalyst.rules._
import org.apache.spark.sql.internal.SQLConf
import org.apache.spark.sql.types.BooleanType

class BooleanSimplificationSuite extends PlanTest with PredicateHelper {
class BooleanSimplificationSuite extends PlanTest with ExpressionEvalHelper with PredicateHelper {

object Optimize extends RuleExecutor[LogicalPlan] {
val batches =
Expand Down Expand Up @@ -71,6 +71,14 @@ class BooleanSimplificationSuite extends PlanTest with PredicateHelper {
comparePlans(actual, correctAnswer)
}

private def checkConditionInNotNullableRelation(
input: Expression, expected: Expression): Unit = {
val plan = testNotNullableRelationWithData.where(input).analyze
val actual = Optimize.execute(plan)
val correctAnswer = testNotNullableRelationWithData.where(expected).analyze
comparePlans(actual, correctAnswer)
}

private def checkConditionInNotNullableRelation(
input: Expression, expected: LogicalPlan): Unit = {
val plan = testNotNullableRelationWithData.where(input).analyze
Expand Down Expand Up @@ -119,42 +127,55 @@ class BooleanSimplificationSuite extends PlanTest with PredicateHelper {
'a === 'b || 'b > 3 && 'a > 3 && 'a < 5)
}

test("e && (!e || f)") {
checkCondition('e && (!'e || 'f ), 'e && 'f)
test("e && (!e || f) - not nullable") {
checkConditionInNotNullableRelation('e && (!'e || 'f ), 'e && 'f)

checkCondition('e && ('f || !'e ), 'e && 'f)
checkConditionInNotNullableRelation('e && ('f || !'e ), 'e && 'f)

checkCondition((!'e || 'f ) && 'e, 'f && 'e)
checkConditionInNotNullableRelation((!'e || 'f ) && 'e, 'f && 'e)

checkCondition(('f || !'e ) && 'e, 'f && 'e)
checkConditionInNotNullableRelation(('f || !'e ) && 'e, 'f && 'e)
}

test("a < 1 && (!(a < 1) || f)") {
checkCondition('a < 1 && (!('a < 1) || 'f), ('a < 1) && 'f)
checkCondition('a < 1 && ('f || !('a < 1)), ('a < 1) && 'f)
test("e && (!e || f) - nullable") {
Seq ('e && (!'e || 'f ),
'e && ('f || !'e ),
(!'e || 'f ) && 'e,
('f || !'e ) && 'e,
'e || (!'e && 'f),
'e || ('f && !'e),
('e && 'f) || !'e,
('f && 'e) || !'e).foreach { expr =>
checkCondition(expr, expr)
}
}

checkCondition('a <= 1 && (!('a <= 1) || 'f), ('a <= 1) && 'f)
checkCondition('a <= 1 && ('f || !('a <= 1)), ('a <= 1) && 'f)
test("a < 1 && (!(a < 1) || f) - not nullable") {
checkConditionInNotNullableRelation('a < 1 && (!('a < 1) || 'f), ('a < 1) && 'f)
checkConditionInNotNullableRelation('a < 1 && ('f || !('a < 1)), ('a < 1) && 'f)

checkCondition('a > 1 && (!('a > 1) || 'f), ('a > 1) && 'f)
checkCondition('a > 1 && ('f || !('a > 1)), ('a > 1) && 'f)
checkConditionInNotNullableRelation('a <= 1 && (!('a <= 1) || 'f), ('a <= 1) && 'f)
checkConditionInNotNullableRelation('a <= 1 && ('f || !('a <= 1)), ('a <= 1) && 'f)

checkCondition('a >= 1 && (!('a >= 1) || 'f), ('a >= 1) && 'f)
checkCondition('a >= 1 && ('f || !('a >= 1)), ('a >= 1) && 'f)
checkConditionInNotNullableRelation('a > 1 && (!('a > 1) || 'f), ('a > 1) && 'f)
checkConditionInNotNullableRelation('a > 1 && ('f || !('a > 1)), ('a > 1) && 'f)

checkConditionInNotNullableRelation('a >= 1 && (!('a >= 1) || 'f), ('a >= 1) && 'f)
checkConditionInNotNullableRelation('a >= 1 && ('f || !('a >= 1)), ('a >= 1) && 'f)
}

test("a < 1 && ((a >= 1) || f)") {
checkCondition('a < 1 && ('a >= 1 || 'f ), ('a < 1) && 'f)
checkCondition('a < 1 && ('f || 'a >= 1), ('a < 1) && 'f)
test("a < 1 && ((a >= 1) || f) - not nullable") {
checkConditionInNotNullableRelation('a < 1 && ('a >= 1 || 'f ), ('a < 1) && 'f)
checkConditionInNotNullableRelation('a < 1 && ('f || 'a >= 1), ('a < 1) && 'f)

checkCondition('a <= 1 && ('a > 1 || 'f ), ('a <= 1) && 'f)
checkCondition('a <= 1 && ('f || 'a > 1), ('a <= 1) && 'f)
checkConditionInNotNullableRelation('a <= 1 && ('a > 1 || 'f ), ('a <= 1) && 'f)
checkConditionInNotNullableRelation('a <= 1 && ('f || 'a > 1), ('a <= 1) && 'f)

checkCondition('a > 1 && (('a <= 1) || 'f), ('a > 1) && 'f)
checkCondition('a > 1 && ('f || ('a <= 1)), ('a > 1) && 'f)
checkConditionInNotNullableRelation('a > 1 && (('a <= 1) || 'f), ('a > 1) && 'f)
checkConditionInNotNullableRelation('a > 1 && ('f || ('a <= 1)), ('a > 1) && 'f)

checkCondition('a >= 1 && (('a < 1) || 'f), ('a >= 1) && 'f)
checkCondition('a >= 1 && ('f || ('a < 1)), ('a >= 1) && 'f)
checkConditionInNotNullableRelation('a >= 1 && (('a < 1) || 'f), ('a >= 1) && 'f)
checkConditionInNotNullableRelation('a >= 1 && ('f || ('a < 1)), ('a >= 1) && 'f)
}

test("DeMorgan's law") {
Expand Down Expand Up @@ -217,4 +238,46 @@ class BooleanSimplificationSuite extends PlanTest with PredicateHelper {
checkCondition('e || !'f, testRelationWithData.where('e || !'f).analyze)
checkCondition(!'f || 'e, testRelationWithData.where(!'f || 'e).analyze)
}

protected def assertEquivalent(e1: Expression, e2: Expression): Unit = {
val correctAnswer = Project(Alias(e2, "out")() :: Nil, OneRowRelation()).analyze
val actual = Optimize.execute(Project(Alias(e1, "out")() :: Nil, OneRowRelation()).analyze)
comparePlans(actual, correctAnswer)
}

test("filter reduction - positive cases") {
val fields = Seq(
'col1NotNULL.boolean.notNull,
'col2NotNULL.boolean.notNull
)
val Seq(col1NotNULL, col2NotNULL) = fields.zipWithIndex.map { case (f, i) => f.at(i) }

val exprs = Seq(
// actual expressions of the transformations: original -> transformed
(col1NotNULL && (!col1NotNULL || col2NotNULL)) -> (col1NotNULL && col2NotNULL),
(col1NotNULL && (col2NotNULL || !col1NotNULL)) -> (col1NotNULL && col2NotNULL),
((!col1NotNULL || col2NotNULL) && col1NotNULL) -> (col2NotNULL && col1NotNULL),
((col2NotNULL || !col1NotNULL) && col1NotNULL) -> (col2NotNULL && col1NotNULL),

(col1NotNULL || (!col1NotNULL && col2NotNULL)) -> (col1NotNULL || col2NotNULL),
(col1NotNULL || (col2NotNULL && !col1NotNULL)) -> (col1NotNULL || col2NotNULL),
((!col1NotNULL && col2NotNULL) || col1NotNULL) -> (col2NotNULL || col1NotNULL),
((col2NotNULL && !col1NotNULL) || col1NotNULL) -> (col2NotNULL || col1NotNULL)
)

// check plans
for ((originalExpr, expectedExpr) <- exprs) {
assertEquivalent(originalExpr, expectedExpr)
}

// check evaluation
val binaryBooleanValues = Seq(true, false)
for (col1NotNULLVal <- binaryBooleanValues;
col2NotNULLVal <- binaryBooleanValues;
(originalExpr, expectedExpr) <- exprs) {
val inputRow = create_row(col1NotNULLVal, col2NotNULLVal)
val optimizedVal = evaluateWithoutCodegen(expectedExpr, inputRow)
checkEvaluation(originalExpr, optimizedVal, inputRow)
}
}
}
10 changes: 10 additions & 0 deletions sql/core/src/test/scala/org/apache/spark/sql/DataFrameSuite.scala
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Expand Up @@ -30,6 +30,7 @@ import org.apache.spark.SparkException
import org.apache.spark.scheduler.{SparkListener, SparkListenerJobEnd}
import org.apache.spark.sql.catalyst.TableIdentifier
import org.apache.spark.sql.catalyst.expressions.Uuid
import org.apache.spark.sql.catalyst.optimizer.ConvertToLocalRelation
import org.apache.spark.sql.catalyst.plans.logical.{Filter, OneRowRelation, Union}
import org.apache.spark.sql.execution.{FilterExec, QueryExecution, WholeStageCodegenExec}
import org.apache.spark.sql.execution.aggregate.HashAggregateExec
Expand Down Expand Up @@ -2567,4 +2568,13 @@ class DataFrameSuite extends QueryTest with SharedSQLContext {

checkAnswer(df.where("(NOT a) OR a"), Seq.empty)
}

test("SPARK-25714 Null handling in BooleanSimplification") {
withSQLConf(SQLConf.OPTIMIZER_EXCLUDED_RULES.key -> ConvertToLocalRelation.ruleName) {
val df = Seq(("abc", 1), (null, 3)).toDF("col1", "col2")
checkAnswer(
df.filter("col1 = 'abc' OR (col1 != 'abc' AND col2 == 3)"),
Row ("abc", 1))
}
}
}