Packages

case class OptimizeSkewedJoin(ensureRequirements: EnsureRequirements) extends Rule[SparkPlan] with Product with Serializable

A rule to optimize skewed joins to avoid straggler tasks whose share of data are significantly larger than those of the rest of the tasks.

The general idea is to divide each skew partition into smaller partitions and replicate its matching partition on the other side of the join so that they can run in parallel tasks. Note that when matching partitions from the left side and the right side both have skew, it will become a cartesian product of splits from left and right joining together.

For example, assume the Sort-Merge join has 4 partitions: left: [L1, L2, L3, L4] right: [R1, R2, R3, R4]

Let's say L2, L4 and R3, R4 are skewed, and each of them get split into 2 sub-partitions. This is scheduled to run 4 tasks at the beginning: (L1, R1), (L2, R2), (L3, R3), (L4, R4). This rule expands it to 9 tasks to increase parallelism: (L1, R1), (L2-1, R2), (L2-2, R2), (L3, R3-1), (L3, R3-2), (L4-1, R4-1), (L4-2, R4-1), (L4-1, R4-2), (L4-2, R4-2)

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Serializable, Product, Equals, Rule[SparkPlan], Logging, SQLConfHelper, AnyRef, Any
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  1. OptimizeSkewedJoin
  2. Serializable
  3. Product
  4. Equals
  5. Rule
  6. Logging
  7. SQLConfHelper
  8. AnyRef
  9. Any
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Visibility
  1. Public
  2. Protected

Instance Constructors

  1. new OptimizeSkewedJoin(ensureRequirements: EnsureRequirements)

Type Members

  1. implicit class LogStringContext extends AnyRef
    Definition Classes
    Logging

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##: Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def apply(plan: SparkPlan): SparkPlan
    Definition Classes
    OptimizeSkewedJoin → Rule
  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.CloneNotSupportedException]) @IntrinsicCandidate() @native()
  7. def conf: SQLConf
    Definition Classes
    SQLConfHelper
  8. val ensureRequirements: EnsureRequirements
  9. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  10. final def getClass(): Class[_ <: AnyRef]
    Definition Classes
    AnyRef → Any
    Annotations
    @IntrinsicCandidate() @native()
  11. def getSkewThreshold(medianSize: Long): Long

    A partition is considered as a skewed partition if its size is larger than the median partition size * SKEW_JOIN_SKEWED_PARTITION_FACTOR and also larger than SKEW_JOIN_SKEWED_PARTITION_THRESHOLD.

    A partition is considered as a skewed partition if its size is larger than the median partition size * SKEW_JOIN_SKEWED_PARTITION_FACTOR and also larger than SKEW_JOIN_SKEWED_PARTITION_THRESHOLD. Thus we pick the larger one as the skew threshold.

  12. def initializeLogIfNecessary(isInterpreter: Boolean, silent: Boolean): Boolean
    Attributes
    protected
    Definition Classes
    Logging
  13. def initializeLogIfNecessary(isInterpreter: Boolean): Unit
    Attributes
    protected
    Definition Classes
    Logging
  14. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  15. def isTraceEnabled(): Boolean
    Attributes
    protected
    Definition Classes
    Logging
  16. def log: Logger
    Attributes
    protected
    Definition Classes
    Logging
  17. def logDebug(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  18. def logDebug(entry: LogEntry, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  19. def logDebug(entry: LogEntry): Unit
    Attributes
    protected
    Definition Classes
    Logging
  20. def logDebug(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  21. def logError(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  22. def logError(entry: LogEntry, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  23. def logError(entry: LogEntry): Unit
    Attributes
    protected
    Definition Classes
    Logging
  24. def logError(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  25. def logInfo(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  26. def logInfo(entry: LogEntry, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  27. def logInfo(entry: LogEntry): Unit
    Attributes
    protected
    Definition Classes
    Logging
  28. def logInfo(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  29. def logName: String
    Attributes
    protected
    Definition Classes
    Logging
  30. def logTrace(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  31. def logTrace(entry: LogEntry, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  32. def logTrace(entry: LogEntry): Unit
    Attributes
    protected
    Definition Classes
    Logging
  33. def logTrace(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  34. def logWarning(msg: => String, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  35. def logWarning(entry: LogEntry, throwable: Throwable): Unit
    Attributes
    protected
    Definition Classes
    Logging
  36. def logWarning(entry: LogEntry): Unit
    Attributes
    protected
    Definition Classes
    Logging
  37. def logWarning(msg: => String): Unit
    Attributes
    protected
    Definition Classes
    Logging
  38. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  39. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @IntrinsicCandidate() @native()
  40. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @IntrinsicCandidate() @native()
  41. def optimizeSkewJoin(plan: SparkPlan): SparkPlan
  42. def productElementNames: Iterator[String]
    Definition Classes
    Product
  43. lazy val ruleId: RuleId
    Attributes
    protected
    Definition Classes
    Rule
  44. val ruleName: String
    Definition Classes
    Rule
  45. final def synchronized[T0](arg0: => T0): T0
    Definition Classes
    AnyRef
  46. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  47. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException]) @native()
  48. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.InterruptedException])
  49. def withLogContext(context: HashMap[String, String])(body: => Unit): Unit
    Attributes
    protected
    Definition Classes
    Logging
  50. def withSQLConf[T](pairs: (String, String)*)(f: => T): T
    Attributes
    protected
    Definition Classes
    SQLConfHelper
  51. object ShuffleStage

Deprecated Value Members

  1. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws(classOf[java.lang.Throwable]) @Deprecated
    Deprecated

    (Since version 9)

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from Rule[SparkPlan]

Inherited from Logging

Inherited from SQLConfHelper

Inherited from AnyRef

Inherited from Any

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