From e22627894126dceb7491300b63f1fe028b1e2e2c Mon Sep 17 00:00:00 2001
From: gatorsmile <gatorsmile@gmail.com>
Date: Mon, 11 Jul 2016 16:21:13 +0800
Subject: [PATCH] [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.
---
.../sql/catalyst/analysis/CheckAnalysis.scala | 19 ++++++++
.../plans/logical/basicLogicalOperators.scala | 16 ++++++-
.../analysis/AnalysisErrorSuite.scala | 6 +++
.../org/apache/spark/sql/SQLQuerySuite.scala | 37 +++++++++++++++-
.../apache/spark/sql/StatisticsSuite.scala | 44 +++++++++++++++++++
5 files changed, 118 insertions(+), 4 deletions(-)
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 7b30fcc6c5..8b87a4e41c 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
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 79f9a210a3..c0e400f617 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)
}
}
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 a9cde1e19e..ff112c5169 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
@@ -352,6 +352,12 @@ class AnalysisErrorSuite extends AnalysisTest {
"Generators are not supported outside the SELECT clause, but got: Sort" :: Nil
)
+ 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)),
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 dca9e5e503..ede7d9a0c9 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"),
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 4de3cf605c..ab55242ec0 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}")
+ }
+ }
+
}
--
GitLab