hvanhovell commented on a change in pull request #21055: [SPARK-23693][SQL] Functions to generate UUIDs URL: https://github.com/apache/spark/pull/21055#discussion_r243777362
########## File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/RandomBasedUuid.scala ########## @@ -0,0 +1,62 @@ +/* + * 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.expressions + +import java.util.Random + +import com.fasterxml.uuid.Generators + +import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode, FalseLiteral} + +@ExpressionDescription( + usage = "_FUNC_() - Returns a random-based universally unique identifier (UUID)." + + " The value is returned as a canonical UUID 36-character string.", + examples = """ + Examples: + > SELECT _FUNC_(); + 46707d92-02f4-4817-8116-a4c3b23e6266 + """, + since = "2.4.0" +) +case class RandomBasedUuid(randomSeed: Option[Long] = None) extends UuidExpression { + + def this() = this(None) + + override lazy val resolved: Boolean = randomSeed.isDefined + + override protected def initializeInternal(partitionIndex: Int): Unit = { + generator = Generators.randomBasedGenerator(new Random(randomSeed.get + partitionIndex)) Review comment: `java.util.Random` only has 48 bits of entropy and it cannot create all possible long value because of that. This makes collisions far more likely. You will need a better PRNG here. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected] With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
