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[SPARK-33884][SQL] Simplify CaseWhenclauses with (true and false) and (false and true) #30898

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[SPARK-33884][SQL] Simplify CaseWhenclauses with (true and false) and (false and true) #30898

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c78882a
simplify CaseWhen when one clause is null and another is boolean
wangyum Dec 23, 2020
44733f8
Add test to PushFoldableIntoBranchesSuite
wangyum Dec 23, 2020
15c74ca
Merge remote-tracking branch 'upstream/master' into SPARK-33884
wangyum Dec 24, 2020
afbded1
Merge remote-tracking branch 'upstream/master' into SPARK-33884
wangyum Dec 24, 2020
91ec8b2
fix
wangyum Dec 25, 2020
871d29f
fix
wangyum Dec 25, 2020
ae3b284
fix
wangyum Dec 28, 2020
186a3d5
Merge remote-tracking branch 'upstream/master' into SPARK-33884
wangyum Dec 29, 2020
d3b072e
fix
wangyum Dec 29, 2020
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simplify CaseWhen when one clause is null and another is boolean
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@wangyum
wangyum committed Dec 23, 2020
commit c78882a1dd06c90c5971b6ac86a0f12561b7ca4f
13 changes: 13 additions & 0 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala
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Expand Up @@ -484,6 +484,19 @@ object SimplifyConditionals extends Rule[LogicalPlan] with PredicateHelper {
case If(cond, FalseLiteral, l @ Literal(null, _)) if !cond.nullable => And(Not(cond), l)
case If(cond, TrueLiteral, l @ Literal(null, _)) if !cond.nullable => Or(cond, l)

case CaseWhen(Seq((cond, l @ Literal(null, _))), Some(FalseLiteral))
if !cond.nullable =>
And(cond, l)
case CaseWhen(Seq((cond, l @ Literal(null, _))), Some(TrueLiteral))
if !cond.nullable =>
Or(Not(cond), l)
case CaseWhen(Seq((cond, FalseLiteral)), elseOpt @ (Some(Literal(null, BooleanType)) | None))
if !cond.nullable =>
And(Not(cond), elseOpt.getOrElse(Literal(null, BooleanType)))
case CaseWhen(Seq((cond, TrueLiteral)), elseOpt @ (Some(Literal(null, BooleanType)) | None))
if !cond.nullable =>
Or(cond, elseOpt.getOrElse(Literal(null, BooleanType)))

case e @ CaseWhen(branches, elseValue) if branches.exists(x => falseOrNullLiteral(x._1)) =>
// If there are branches that are always false, remove them.
// If there are no more branches left, just use the else value.
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48 changes: 48 additions & 0 deletions ...yst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/SimplifyConditionalSuite.scala
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Expand Up @@ -215,4 +215,52 @@ class SimplifyConditionalSuite extends PlanTest with ExpressionEvalHelper with P
If(GreaterThan(Rand(0), UnresolvedAttribute("a")), FalseLiteral, TrueLiteral),
LessThanOrEqual(Rand(0), UnresolvedAttribute("a")))
}

test("SPARK-33884: simplify CaseWhen when one clause is null and another is boolean") {
val p = IsNull('a)
val nullLiteral = Literal(null, BooleanType)
assertEquivalent(CaseWhen(Seq((p, nullLiteral)), FalseLiteral), And(p, nullLiteral))
assertEquivalent(CaseWhen(Seq((p, nullLiteral)), TrueLiteral), Or(IsNotNull('a), nullLiteral))
assertEquivalent(CaseWhen(Seq((p, FalseLiteral)), nullLiteral), And(IsNotNull('a), nullLiteral))
assertEquivalent(CaseWhen(Seq((p, FalseLiteral)), None), And(IsNotNull('a), nullLiteral))
assertEquivalent(CaseWhen(Seq((p, TrueLiteral)), nullLiteral), Or(p, nullLiteral))
assertEquivalent(CaseWhen(Seq((p, TrueLiteral)), None), Or(p, nullLiteral))

// the rule should not apply to nullable predicate
Seq(TrueLiteral, FalseLiteral).foreach { b =>
assertEquivalent(CaseWhen(Seq((GreaterThan('a, 42), nullLiteral)), b),
CaseWhen(Seq((GreaterThan('a, 42), nullLiteral)), b))
assertEquivalent(CaseWhen(Seq((GreaterThan('a, 42), b)), nullLiteral),
CaseWhen(Seq((GreaterThan('a, 42), b)), nullLiteral))
assertEquivalent(CaseWhen(Seq((GreaterThan('a, 42), b)), None),
CaseWhen(Seq((GreaterThan('a, 42), b)), None))
}

// check evaluation also
Seq(TrueLiteral, FalseLiteral).foreach { b =>
checkEvaluation(CaseWhen(Seq((b, nullLiteral)), FalseLiteral),
And(b, nullLiteral).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((b, nullLiteral)), TrueLiteral),
Or(Not(b), nullLiteral).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((b, FalseLiteral)), nullLiteral),
And(Not(b), nullLiteral).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((b, FalseLiteral)), None),
And(Not(b), nullLiteral).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((b, TrueLiteral)), nullLiteral),
Or(b, nullLiteral).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((b, TrueLiteral)), None),
Or(b, nullLiteral).eval(EmptyRow))
}

// should have no effect on expressions with nullable if condition
assert((Factorial(5) > 100L).nullable)
Seq(TrueLiteral, FalseLiteral).foreach { b =>
checkEvaluation(CaseWhen(Seq((Factorial(5) > 100L, nullLiteral)), b),
CaseWhen(Seq((Factorial(5) > 100L, nullLiteral)), b).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((Factorial(5) > 100L, b)), nullLiteral),
CaseWhen(Seq((Factorial(5) > 100L, b)), nullLiteral).eval(EmptyRow))
checkEvaluation(CaseWhen(Seq((Factorial(5) > 100L, b)), None),
CaseWhen(Seq((Factorial(5) > 100L, b)), None).eval(EmptyRow))
}
}
}