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[SPARK-6040][SQL] Fix the percent bug in tablesample #4789

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watermen wants to merge 1 commit into from
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[SPARK-6040][SQL] Fix the percent bug in tablesample #4789

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11 changes: 10 additions & 1 deletion sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ import org.apache.spark.sql.execution.ExplainCommand
import org.apache.spark.sql.sources.DescribeCommand
import org.apache.spark.sql.hive.execution.{HiveNativeCommand, DropTable, AnalyzeTable, HiveScriptIOSchema}
import org.apache.spark.sql.types._
import org.apache.spark.util.random.RandomSampler

/* Implicit conversions */
import scala.collection.JavaConversions._
Expand Down Expand Up @@ -850,7 +851,15 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
case Token("TOK_TABLESPLITSAMPLE",
Token("TOK_PERCENT", Nil) ::
Token(fraction, Nil) :: Nil) =>
Sample(fraction.toDouble, withReplacement = false, (math.random * 1000).toInt, relation)
// The range of fraction accepted by Sample is [0, 1]. Because Hive's block sampling
// function takes X PERCENT as the input and the range of X is [0, 100], we need to
// adjust the fraction.
require(
fraction.toDouble >= (0.0 - RandomSampler.roundingEpsilon)
&& fraction.toDouble <= (100.0 + RandomSampler.roundingEpsilon),
s"Sampling fraction ($fraction) must be on interval [0, 100]")
Sample(fraction.toDouble / 100, withReplacement = false, (math.random * 1000).toInt,
relation)
case Token("TOK_TABLEBUCKETSAMPLE",
Token(numerator, Nil) ::
Token(denominator, Nil) :: Nil) =>
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1 change: 1 addition & 0 deletions sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveQuerySuite.scala
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Expand Up @@ -467,6 +467,7 @@ class HiveQuerySuite extends HiveComparisonTest with BeforeAndAfter {

test("sampling") {
sql("SELECT * FROM src TABLESAMPLE(0.1 PERCENT) s")
sql("SELECT * FROM src TABLESAMPLE(100 PERCENT) s")
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@marmbrus marmbrus Mar 2, 2015

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I'm going to go ahead and merge this since it changes semantics and we are close to the release where we remove the alpha tag, but it would be great if you could add a test that actually checks to make sure sampling is happening and we are getting something close to the expected number of results.

}

test("DataFrame toString") {
Expand Down