Module org.elasticsearch.compute
Package org.elasticsearch.compute.operator

Class SparklineGenerateEmptyBucketsOperator

java.lang.Object
org.elasticsearch.compute.operator.SparklineGenerateEmptyBucketsOperator
All Implemented Interfaces:
Closeable, AutoCloseable, Operator, Releasable
public class SparklineGenerateEmptyBucketsOperator extends Object implements Operator
Fills in zero-valued buckets for data produced by the last sparkline aggregation phase and stops the @timestamp columns. Let's take an example: 
| STATS mi=SPARKLINE(   MAX(int), @timestamp, 3, "2025-01-01", "2025-01-03"),
        md=SPARKLINE(MIN(double), @timestamp, 3, "2025-01-01", "2025-01-03")
     BY hostname

That's going to produce output like: 

┌───────────────┬──────────────────┬──────────┐
│ MIN(int)      │ MAX(double)      │ hostname │
├───────────────┼──────────────────┼──────────┤
│ [10, 20, 30]  │ [1.0, 2.0, 3.0]  │ yay      │
│ [42,  0, 99]  │ [4.2, 0.0, 9.9]  │ server   │
└───────────────┴──────────────────┴──────────┘

To get there the original ESQL is rewritten into: 

| STATS mi=MAX(int), md=MIN(double), BY @timestamp=DATE_TRUNC(1 day, @timestamp), hostname
| STATS TOP(@timestamp, 3, "asc", mi), TOP(@timestamp, 3, "asc", md), TOP(@timestamp, 3, "asc")
       BY hostname
| SPARKLINE_GENERATE_EMPTY_BUCKETS <-- you are here

The first STATS is just pretty normal agg. Imagine it returns something like: 

┌───────────────┬──────────────────┬────────────┬──────────┐
│ MIN(int)      │ MAX(double)      │ @timestamp │ hostname │
├───────────────┼──────────────────┼────────────┼──────────┤
│ 10            │ 1.0              │ 2025-01-01 │ yay      │
│ 20            │ 2.0              │ 2025-01-02 │ yay      │
│ 30            │ 3.0              │ 2025-01-03 │ yay      │
│ 42            │ 4.2              │ 2025-01-01 │ server   │
│ 99            │ 9.9              │ 2025-01-03 │ server   │
└───────────────┴──────────────────┴────────────┴──────────┘

The second STATS collects the results into the arrays that the output layout expects. But have a look: 

┌───────────────┬──────────────────┬──────────────────────────────────────┬──────────┐
│ MIN(int)      │ MAX(double)      │ @timestamp                           │ hostname │
├───────────────┼──────────────────┼──────────────────────────────────────┼──────────┤
│ [10, 20, 30]  │ [1.0, 2.0, 3.0]  │ [2025-01-01, 2025-01-02, 2025-01-03] │ yay      │
│ [42, 99]      │ [4.2, 9.9]       │ [2025-01-01, 2025-01-03]             │ server   │
└───────────────┴──────────────────┴──────────────────────────────────────┴──────────┘

See?! The second row is complete - ready! It's what we want! Well, it has a @timestamp we don't want, but it's close! But the second row is trouble. It's missing the value for 2025-01-02. You can tell which day is missing by looking at the timestamp. This operator fills in the 0. It'll consume the data above and make: 

┌───────────────┬──────────────────┬──────────┐
│ MIN(int)      │ MAX(double)      │ hostname │
├───────────────┼──────────────────┼──────────┤
│ [10, 20, 30]  │ [1.0, 2.0, 3.0]  │ yay      │
│ [42,  0, 99]  │ [4.2, 0.0, 9.9]  │ server   │
└───────────────┴──────────────────┴──────────┘

And that is exactly what we want.

  • Constructor Details

    • SparklineGenerateEmptyBucketsOperator

      public SparklineGenerateEmptyBucketsOperator(DriverContext driverContext, int numValueColumns, Rounding.Prepared dateBucketRounding, long minDate, long maxDate)

  • Method Details

    • needsInput

      public boolean needsInput()
      Description copied from interface: Operator
      whether the given operator can accept more input pages
      Specified by:
      needsInput in interface Operator

    • addInput

      public void addInput(Page page)
      Description copied from interface: Operator
      adds an input page to the operator. only called when needsInput() == true and isFinished() == false
      Specified by:
      addInput in interface Operator

    • finish

      public void finish()
      Description copied from interface: Operator
      notifies the operator that it won't receive any more input pages
      Specified by:
      finish in interface Operator

    • isFinished

      public boolean isFinished()
      Description copied from interface: Operator
      whether the operator has finished processing all input pages and made the corresponding output pages available
      Specified by:
      isFinished in interface Operator

    • canProduceMoreDataWithoutExtraInput

      public boolean canProduceMoreDataWithoutExtraInput()
      Description copied from interface: Operator
      Returns true if the operator can produce more output pages without requiring additional input pages. This is useful for operators that buffer data or have internal state that can produce multiple output pages.

      Operators that do not buffer data should return false - they cannot produce pages out of thin air. Examples of operators that may return true:

      • Operators with internal buffers (e.g., AsyncOperator with pending results)
      • Operators processing a single input page into multiple output pages
      • Aggregation operators that buffer partial results
      Specified by:
      canProduceMoreDataWithoutExtraInput in interface Operator
      Returns:
      true if the operator has buffered data that can produce output, false otherwise

    • getOutput

      public Page getOutput()
      Description copied from interface: Operator
      returns non-null if output page available. Only called when isFinished() == false
      Specified by:
      getOutput in interface Operator

    • close

      public void close()
      Description copied from interface: Operator
      notifies the operator that it won't be used anymore (i.e. none of the other methods called), and its resources can be cleaned up
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Specified by:
      close in interface Operator
      Specified by:
      close in interface Releasable

    • toString

      public String toString()
      Overrides:
      toString in class Object