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[SPARK-35207][SQL] Normalize hash function behavior with negative zero (floating point types) #32496

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[SPARK-35207][SQL] Normalize hash function behavior with negative zero (floating point types) #32496

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planga82 May 11, 2021
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planga82 May 12, 2021
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Merge remote-tracking branch 'upstream/master' into feature/spark3520…
planga82 May 13, 2021
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planga82 May 14, 2021
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planga82 May 14, 2021
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@planga82
planga82 committed May 13, 2021
commit 1de9c3d6f15fe230b61fc30dee6c539248f0e403
4 changes: 2 additions & 2 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/hash.scala
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Expand Up @@ -371,7 +371,7 @@ abstract class HashExpression[E] extends Expression {

protected def genHashFloat(input: String, result: String): String = {
s"""
|if(Float.floatToIntBits($input) == Float.floatToIntBits(-0.0f)) {
|if($input == -0.0f) {
| ${genHashInt(s"Float.floatToIntBits(0.0f)", result)}
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@dongjoon-hyun dongjoon-hyun May 13, 2021

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Although this has the semantic, shall we use simply "0" instead of s"Float.floatToIntBits(0.0f)"? We may add some comment for the semantic instead.

jshell> Float.floatToIntBits(0.0f)
$1 ==> 0

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@planga82 planga82 May 14, 2021

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You are right, I have tested it to be sure.
Murmur3HashFunction.hashInt(java.lang.Float.floatToIntBits(0.0f), 42) == Murmur3HashFunction.hashInt(0, 42)
It is simpler.

|} else {
| ${genHashInt(s"Float.floatToIntBits($input)", result)}
Expand All @@ -381,7 +381,7 @@ abstract class HashExpression[E] extends Expression {

protected def genHashDouble(input: String, result: String): String = {
s"""
|if(Double.doubleToLongBits($input) == Double.doubleToLongBits(-0.0d)) {
|if($input == -0.0d) {
| ${genHashLong(s"Double.doubleToLongBits(0.0d)", result)}
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@dongjoon-hyun dongjoon-hyun May 13, 2021

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ditto. We had better use the simplest constant here instead of s"Double.doubleToLongBits(0.0d)".

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@dongjoon-hyun dongjoon-hyun May 13, 2021

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In this case, 0L?

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@planga82 planga82 May 14, 2021

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The same as the previous point, thanks

|} else {
| ${genHashLong(s"Double.doubleToLongBits($input)", result)}
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11 changes: 6 additions & 5 deletions ...alyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/HashExpressionsSuite.scala
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Expand Up @@ -710,12 +710,13 @@ class HashExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper {

test("SPARK-35207: Compute hash consistent between -0.0 and 0.0") {
def checkResult(exprs1: Expression, exprs2: Expression): Unit = {
assert(Murmur3Hash(Seq(exprs1), 42).eval() == Murmur3Hash(Seq(exprs2), 42).eval())
assert(XxHash64(Seq(exprs1), 42).eval() == XxHash64(Seq(exprs2), 42).eval())
assert(HiveHash(Seq(exprs1)).eval() == HiveHash(Seq(exprs2)).eval())
checkEvaluation(Murmur3Hash(Seq(exprs1), 42), Murmur3Hash(Seq(exprs2), 42).eval())
checkEvaluation(XxHash64(Seq(exprs1), 42), XxHash64(Seq(exprs2), 42).eval())
checkEvaluation(HiveHash(Seq(exprs1)), HiveHash(Seq(exprs2)).eval())
}
checkResult(Literal.create(0D, DoubleType), Literal.create(-0D, DoubleType))
checkResult(Literal.create(0L, LongType), Literal.create(-0L, LongType))

checkResult(Literal.create(-0D, DoubleType), Literal.create(0D, DoubleType))
checkResult(Literal.create(-0F, FloatType), Literal.create(0F, FloatType))
}

private def testHash(inputSchema: StructType): Unit = {
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26 changes: 0 additions & 26 deletions sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
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Expand Up @@ -708,30 +708,4 @@ class WholeStageCodegenSuite extends QueryTest with SharedSparkSession
}
}
}

test("SPARK-35207: Compute hash consistent between -0.0 and 0.0 doubles with Codegen") {
val data = Seq((0.0d, -1.0d, 1.0d))
withTempPath { dir =>
val path = dir.getCanonicalPath
data.toDF("col1", "col2", "col3").write.parquet(path)
sql(s"create table testHash(col1 double, col2 double, col3 double) " +
s"using parquet location '$path'")
sql("select hash(col1 / col2) == hash(col1 / col3) from testHash").collect()
.foreach(row => assert(row.getBoolean(0) == true))
sql("drop table testHash")
}
}

test("SPARK-35207: Compute hash consistent between -0.0 and 0.0 floats with Codegen") {
val data = Seq((0.0f, -1.0f, 1.0f))
withTempPath { dir =>
val path = dir.getCanonicalPath
data.toDF("col1", "col2", "col3").write.parquet(path)
sql(s"create table testHash(col1 float, col2 float, col3 float) " +
s"using parquet location '$path'")
sql("select hash(col1 / col2) == hash(col1 / col3) from testHash").collect()
.foreach(row => assert(row.getBoolean(0) == true))
sql("drop table testHash")
}
}
}