Packages

object TimeWindowing extends Rule[LogicalPlan]

Maps a time column to multiple time windows using the Expand operator. Since it's non-trivial to figure out how many windows a time column can map to, we over-estimate the number of windows and filter out the rows where the time column is not inside the time window.

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Rule[LogicalPlan], Logging, AnyRef, Any
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  1. final def !=(arg0: Any): Boolean
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    AnyRef → Any
  2. final def ##(): Int
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  3. final def ==(arg0: Any): Boolean
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  4. def apply(plan: LogicalPlan): LogicalPlan

    Generates the logical plan for generating window ranges on a timestamp column.

    Generates the logical plan for generating window ranges on a timestamp column. Without knowing what the timestamp value is, it's non-trivial to figure out deterministically how many window ranges a timestamp will map to given all possible combinations of a window duration, slide duration and start time (offset). Therefore, we express and over-estimate the number of windows there may be, and filter the valid windows. We use last Project operator to group the window columns into a struct so they can be accessed as window.start and window.end.

    The windows are calculated as below: maxNumOverlapping <- ceil(windowDuration / slideDuration) for (i <- 0 until maxNumOverlapping) windowId <- ceil((timestamp - startTime) / slideDuration) windowStart <- windowId * slideDuration + (i - maxNumOverlapping) * slideDuration + startTime windowEnd <- windowStart + windowDuration return windowStart, windowEnd

    This behaves as follows for the given parameters for the time: 12:05. The valid windows are marked with a +, and invalid ones are marked with a x. The invalid ones are filtered using the Filter operator. window: 12m, slide: 5m, start: 0m :: window: 12m, slide: 5m, start: 2m 11:55 - 12:07 + 11:52 - 12:04 x 12:00 - 12:12 + 11:57 - 12:09 + 12:05 - 12:17 + 12:02 - 12:14 +

    plan

    The logical plan

    returns

    the logical plan that will generate the time windows using the Expand operator, with the Filter operator for correctness and Project for usability.

    Definition Classes
    TimeWindowing → Rule
  5. final def asInstanceOf[T0]: T0
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  6. def clone(): AnyRef
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    @throws( ... ) @native()
  7. final def eq(arg0: AnyRef): Boolean
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  8. def equals(arg0: Any): Boolean
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  9. def finalize(): Unit
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  11. def hashCode(): Int
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  12. def initializeLogIfNecessary(isInterpreter: Boolean, silent: Boolean): Boolean
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    Logging
  13. def initializeLogIfNecessary(isInterpreter: Boolean): Unit
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  14. final def isInstanceOf[T0]: Boolean
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  15. def isTraceEnabled(): Boolean
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  16. def log: Logger
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  17. def logDebug(msg: ⇒ String, throwable: Throwable): Unit
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  18. def logDebug(msg: ⇒ String): Unit
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  19. def logError(msg: ⇒ String, throwable: Throwable): Unit
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  20. def logError(msg: ⇒ String): Unit
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  21. def logInfo(msg: ⇒ String, throwable: Throwable): Unit
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  22. def logInfo(msg: ⇒ String): Unit
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  23. def logName: String
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  24. def logTrace(msg: ⇒ String, throwable: Throwable): Unit
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  25. def logTrace(msg: ⇒ String): Unit
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  26. def logWarning(msg: ⇒ String, throwable: Throwable): Unit
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  27. def logWarning(msg: ⇒ String): Unit
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  28. final def ne(arg0: AnyRef): Boolean
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  29. final def notify(): Unit
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  30. final def notifyAll(): Unit
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  31. val ruleName: String

    Name for this rule, automatically inferred based on class name.

    Name for this rule, automatically inferred based on class name.

    Definition Classes
    Rule
  32. final def synchronized[T0](arg0: ⇒ T0): T0
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  33. def toString(): String
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  36. final def wait(arg0: Long): Unit
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Inherited from Rule[LogicalPlan]

Inherited from Logging

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