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From wenc...@apache.org
Subject spark git commit: [SPARK-16355][SPARK-16354][SQL] Fix Bugs When LIMIT/TABLESAMPLE is Non-foldable, Zero or Negative
Date Mon, 11 Jul 2016 08:29:02 GMT
Repository: spark
Updated Branches:
  refs/heads/branch-2.0 139d5eae0 -> aa8cbcd19


[SPARK-16355][SPARK-16354][SQL] Fix Bugs When LIMIT/TABLESAMPLE is Non-foldable, Zero or Negative

#### What changes were proposed in this pull request?
**Issue 1:** When a query containing LIMIT/TABLESAMPLE 0, the statistics could be zero. Results
are correct but it could cause a huge performance regression. For example,
```Scala
Seq(("one", 1), ("two", 2), ("three", 3), ("four", 4)).toDF("k", "v")
  .createOrReplaceTempView("test")
val df1 = spark.table("test")
val df2 = spark.table("test").limit(0)
val df = df1.join(df2, Seq("k"), "left")
```
The statistics of both `df` and `df2` are zero. The statistics values should never be zero;
otherwise `sizeInBytes` of `BinaryNode` will also be zero (product of children). This PR is
to increase it to `1` when the num of rows is equal to 0.

**Issue 2:** When a query containing negative LIMIT/TABLESAMPLE, we should issue exceptions.
Negative values could break the implementation assumption of multiple parts. For example,
statistics calculation.  Below is the example query.
```SQL
SELECT * FROM testData TABLESAMPLE (-1 rows)
SELECT * FROM testData LIMIT -1
```
This PR is to issue an appropriate exception in this case.

**Issue 3:** Spark SQL follows the restriction of LIMIT clause in Hive. The argument to the
LIMIT clause must evaluate to a constant value. It can be a numeric literal, or another kind
of numeric expression involving operators, casts, and function return values. You cannot refer
to a column or use a subquery. Currently, we do not detect whether the expression in LIMIT
clause is foldable or not. If non-foldable, we might issue a strange error message. For example,
```SQL
SELECT * FROM testData LIMIT rand() > 0.2
```
Then, a misleading error message is issued, like
```
assertion failed: No plan for GlobalLimit (_nondeterministic#203 > 0.2)
+- Project [key#11, value#12, rand(-1441968339187861415) AS _nondeterministic#203]
   +- LocalLimit (_nondeterministic#202 > 0.2)
      +- Project [key#11, value#12, rand(-1308350387169017676) AS _nondeterministic#202]
         +- LogicalRDD [key#11, value#12]

java.lang.AssertionError: assertion failed: No plan for GlobalLimit (_nondeterministic#203
> 0.2)
+- Project [key#11, value#12, rand(-1441968339187861415) AS _nondeterministic#203]
   +- LocalLimit (_nondeterministic#202 > 0.2)
      +- Project [key#11, value#12, rand(-1308350387169017676) AS _nondeterministic#202]
         +- LogicalRDD [key#11, value#12]
```
This PR detects it and then issues a meaningful error message.

#### How was this patch tested?
Added test cases.

Author: gatorsmile <gatorsmile@gmail.com>

Closes #14034 from gatorsmile/limit.

(cherry picked from commit e22627894126dceb7491300b63f1fe028b1e2e2c)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>


Project: http://git-wip-us.apache.org/repos/asf/spark/repo
Commit: http://git-wip-us.apache.org/repos/asf/spark/commit/aa8cbcd1
Tree: http://git-wip-us.apache.org/repos/asf/spark/tree/aa8cbcd1
Diff: http://git-wip-us.apache.org/repos/asf/spark/diff/aa8cbcd1

Branch: refs/heads/branch-2.0
Commit: aa8cbcd199b5dcfd95b6a5e6f214f291e27d5781
Parents: 139d5ea
Author: gatorsmile <gatorsmile@gmail.com>
Authored: Mon Jul 11 16:21:13 2016 +0800
Committer: Wenchen Fan <wenchen@databricks.com>
Committed: Mon Jul 11 16:27:51 2016 +0800

----------------------------------------------------------------------
 .../sql/catalyst/analysis/CheckAnalysis.scala   | 19 +++++++++
 .../plans/logical/basicLogicalOperators.scala   | 16 ++++++-
 .../catalyst/analysis/AnalysisErrorSuite.scala  |  6 +++
 .../org/apache/spark/sql/SQLQuerySuite.scala    | 37 +++++++++++++++-
 .../org/apache/spark/sql/StatisticsSuite.scala  | 44 ++++++++++++++++++++
 5 files changed, 118 insertions(+), 4 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/spark/blob/aa8cbcd1/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
----------------------------------------------------------------------
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
index 7b30fcc..8b87a4e 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/CheckAnalysis.scala
@@ -46,6 +46,21 @@ trait CheckAnalysis extends PredicateHelper {
     }).length > 1
   }
 
+  private def checkLimitClause(limitExpr: Expression): Unit = {
+    limitExpr match {
+      case e if !e.foldable => failAnalysis(
+        "The limit expression must evaluate to a constant value, but got " +
+          limitExpr.sql)
+      case e if e.dataType != IntegerType => failAnalysis(
+        s"The limit expression must be integer type, but got " +
+          e.dataType.simpleString)
+      case e if e.eval().asInstanceOf[Int] < 0 => failAnalysis(
+        "The limit expression must be equal to or greater than 0, but got " +
+          e.eval().asInstanceOf[Int])
+      case e => // OK
+    }
+  }
+
   def checkAnalysis(plan: LogicalPlan): Unit = {
     // We transform up and order the rules so as to catch the first possible failure instead
     // of the result of cascading resolution failures.
@@ -251,6 +266,10 @@ trait CheckAnalysis extends PredicateHelper {
                 s"but one table has '${firstError.output.length}' columns and another table
has " +
                 s"'${s.children.head.output.length}' columns")
 
+          case GlobalLimit(limitExpr, _) => checkLimitClause(limitExpr)
+
+          case LocalLimit(limitExpr, _) => checkLimitClause(limitExpr)
+
           case p if p.expressions.exists(ScalarSubquery.hasCorrelatedScalarSubquery) =>
             p match {
               case _: Filter | _: Aggregate | _: Project => // Ok

http://git-wip-us.apache.org/repos/asf/spark/blob/aa8cbcd1/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
----------------------------------------------------------------------
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
index 79f9a21..c0e400f 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/basicLogicalOperators.scala
@@ -660,7 +660,13 @@ case class GlobalLimit(limitExpr: Expression, child: LogicalPlan) extends
UnaryN
   }
   override lazy val statistics: Statistics = {
     val limit = limitExpr.eval().asInstanceOf[Int]
-    val sizeInBytes = (limit: Long) * output.map(a => a.dataType.defaultSize).sum
+    val sizeInBytes = if (limit == 0) {
+      // sizeInBytes can't be zero, or sizeInBytes of BinaryNode will also be zero
+      // (product of children).
+      1
+    } else {
+      (limit: Long) * output.map(a => a.dataType.defaultSize).sum
+    }
     child.statistics.copy(sizeInBytes = sizeInBytes)
   }
 }
@@ -675,7 +681,13 @@ case class LocalLimit(limitExpr: Expression, child: LogicalPlan) extends
UnaryNo
   }
   override lazy val statistics: Statistics = {
     val limit = limitExpr.eval().asInstanceOf[Int]
-    val sizeInBytes = (limit: Long) * output.map(a => a.dataType.defaultSize).sum
+    val sizeInBytes = if (limit == 0) {
+      // sizeInBytes can't be zero, or sizeInBytes of BinaryNode will also be zero
+      // (product of children).
+      1
+    } else {
+      (limit: Long) * output.map(a => a.dataType.defaultSize).sum
+    }
     child.statistics.copy(sizeInBytes = sizeInBytes)
   }
 }

http://git-wip-us.apache.org/repos/asf/spark/blob/aa8cbcd1/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisErrorSuite.scala
----------------------------------------------------------------------
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisErrorSuite.scala
b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisErrorSuite.scala
index a9cde1e..ff112c5 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisErrorSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisErrorSuite.scala
@@ -353,6 +353,12 @@ class AnalysisErrorSuite extends AnalysisTest {
   )
 
   errorTest(
+    "num_rows in limit clause must be equal to or greater than 0",
+    listRelation.limit(-1),
+    "The limit expression must be equal to or greater than 0, but got -1" :: Nil
+  )
+
+  errorTest(
     "more than one generators in SELECT",
     listRelation.select(Explode('list), Explode('list)),
     "Only one generator allowed per select clause but found 2: explode(list), explode(list)"
:: Nil

http://git-wip-us.apache.org/repos/asf/spark/blob/aa8cbcd1/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
----------------------------------------------------------------------
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
index dca9e5e..ede7d9a 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/SQLQuerySuite.scala
@@ -660,11 +660,11 @@ class SQLQuerySuite extends QueryTest with SharedSQLContext {
 
   test("limit") {
     checkAnswer(
-      sql("SELECT * FROM testData LIMIT 10"),
+      sql("SELECT * FROM testData LIMIT 9 + 1"),
       testData.take(10).toSeq)
 
     checkAnswer(
-      sql("SELECT * FROM arrayData LIMIT 1"),
+      sql("SELECT * FROM arrayData LIMIT CAST(1 AS Integer)"),
       arrayData.collect().take(1).map(Row.fromTuple).toSeq)
 
     checkAnswer(
@@ -672,6 +672,39 @@ class SQLQuerySuite extends QueryTest with SharedSQLContext {
       mapData.collect().take(1).map(Row.fromTuple).toSeq)
   }
 
+  test("non-foldable expressions in LIMIT") {
+    val e = intercept[AnalysisException] {
+      sql("SELECT * FROM testData LIMIT key > 3")
+    }.getMessage
+    assert(e.contains("The limit expression must evaluate to a constant value, " +
+      "but got (testdata.`key` > 3)"))
+  }
+
+  test("Expressions in limit clause are not integer") {
+    var e = intercept[AnalysisException] {
+      sql("SELECT * FROM testData LIMIT true")
+    }.getMessage
+    assert(e.contains("The limit expression must be integer type, but got boolean"))
+
+    e = intercept[AnalysisException] {
+      sql("SELECT * FROM testData LIMIT 'a'")
+    }.getMessage
+    assert(e.contains("The limit expression must be integer type, but got string"))
+  }
+
+  test("negative in LIMIT or TABLESAMPLE") {
+    val expected = "The limit expression must be equal to or greater than 0, but got -1"
+    var e = intercept[AnalysisException] {
+      sql("SELECT * FROM testData TABLESAMPLE (-1 rows)")
+    }.getMessage
+    assert(e.contains(expected))
+
+    e = intercept[AnalysisException] {
+      sql("SELECT * FROM testData LIMIT -1")
+    }.getMessage
+    assert(e.contains(expected))
+  }
+
   test("CTE feature") {
     checkAnswer(
       sql("with q1 as (select * from testData limit 10) select * from q1"),

http://git-wip-us.apache.org/repos/asf/spark/blob/aa8cbcd1/sql/core/src/test/scala/org/apache/spark/sql/StatisticsSuite.scala
----------------------------------------------------------------------
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/StatisticsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/StatisticsSuite.scala
index 4de3cf6..ab55242 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/StatisticsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/StatisticsSuite.scala
@@ -17,10 +17,12 @@
 
 package org.apache.spark.sql
 
+import org.apache.spark.sql.catalyst.plans.logical.{GlobalLimit, Join, LocalLimit}
 import org.apache.spark.sql.test.SharedSQLContext
 import org.apache.spark.sql.types._
 
 class StatisticsSuite extends QueryTest with SharedSQLContext {
+  import testImplicits._
 
   test("SPARK-15392: DataFrame created from RDD should not be broadcasted") {
     val rdd = sparkContext.range(1, 100).map(i => Row(i, i))
@@ -31,4 +33,46 @@ class StatisticsSuite extends QueryTest with SharedSQLContext {
       spark.sessionState.conf.autoBroadcastJoinThreshold)
   }
 
+  test("estimates the size of limit") {
+    withTempTable("test") {
+      Seq(("one", 1), ("two", 2), ("three", 3), ("four", 4)).toDF("k", "v")
+        .createOrReplaceTempView("test")
+      Seq((0, 1), (1, 24), (2, 48)).foreach { case (limit, expected) =>
+        val df = sql(s"""SELECT * FROM test limit $limit""")
+
+        val sizesGlobalLimit = df.queryExecution.analyzed.collect { case g: GlobalLimit =>
+          g.statistics.sizeInBytes
+        }
+        assert(sizesGlobalLimit.size === 1, s"Size wrong for:\n ${df.queryExecution}")
+        assert(sizesGlobalLimit.head === BigInt(expected),
+          s"expected exact size $expected for table 'test', got: ${sizesGlobalLimit.head}")
+
+        val sizesLocalLimit = df.queryExecution.analyzed.collect { case l: LocalLimit =>
+          l.statistics.sizeInBytes
+        }
+        assert(sizesLocalLimit.size === 1, s"Size wrong for:\n ${df.queryExecution}")
+        assert(sizesLocalLimit.head === BigInt(expected),
+          s"expected exact size $expected for table 'test', got: ${sizesLocalLimit.head}")
+      }
+    }
+  }
+
+  test("estimates the size of a limit 0 on outer join") {
+    withTempTable("test") {
+      Seq(("one", 1), ("two", 2), ("three", 3), ("four", 4)).toDF("k", "v")
+        .createOrReplaceTempView("test")
+      val df1 = spark.table("test")
+      val df2 = spark.table("test").limit(0)
+      val df = df1.join(df2, Seq("k"), "left")
+
+      val sizes = df.queryExecution.analyzed.collect { case g: Join =>
+        g.statistics.sizeInBytes
+      }
+
+      assert(sizes.size === 1, s"number of Join nodes is wrong:\n ${df.queryExecution}")
+      assert(sizes.head === BigInt(96),
+        s"expected exact size 96 for table 'test', got: ${sizes.head}")
+    }
+  }
+
 }


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