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[SPARK-23599][SQL] Add a UUID generator from Pseudo-Random Numbers #20817

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[SPARK-23599][SQL] Add a UUID generator from Pseudo-Random Numbers #20817

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b7bce25
Add a UUID generator from Pseudo-Random Numbers.
viirya Mar 14, 2018
cd73b4c
Use Mersenne Twister as RNG.
viirya Mar 15, 2018
75b80a2
Add API to get UTF8String UUID.
viirya Mar 16, 2018
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Add API to get UTF8String UUID.
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@viirya
viirya committed Mar 16, 2018
commit 75b80a249c9e5492e6fe159ac527feaea4f46c5a
4 changes: 4 additions & 0 deletions sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/RandomUUIDGenerator.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ import java.util.UUID

import org.apache.commons.math3.random.MersenneTwister

import org.apache.spark.unsafe.types.UTF8String

/**
* This class is used to generate a UUID from Pseudo-Random Numbers.
*
Expand All @@ -36,4 +38,6 @@ case class RandomUUIDGenerator(randomSeed: Long) {

new UUID(mostSigBits, leastSigBits)
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@hvanhovell hvanhovell Mar 14, 2018 •
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I think we need to use a different RNG. java.util.Random only has 48 bits of state, which is less than the 122 bits we need for UUID generation. Something like PCG or a Mersenne twister would work.

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@viirya viirya Mar 15, 2018

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Ok. Mersenne Twister is used in the update.

}

def getNextUUIDUTF8String(): UTF8String = UTF8String.fromString(getNextUUID().toString())
}
7 changes: 7 additions & 0 deletions ...catalyst/src/test/scala/org/apache/spark/sql/catalyst/util/RandomUUIDGeneratorSuite.scala
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Expand Up @@ -47,4 +47,11 @@ class RandomUUIDGeneratorSuite extends SparkFunSuite {
assert(uuid1 != uuid3)
}
}

test("Get UTF8String UUID") {
val generator = RandomUUIDGenerator(new Random().nextLong())
val utf8StringUUID = generator.getNextUUIDUTF8String()
val uuid = java.util.UUID.fromString(utf8StringUUID.toString)
assert(uuid.version() == 4 && uuid.variant() == 2 && utf8StringUUID.toString == uuid.toString)
}
}