Package org.apache.drill.exec.physical.impl.xsort

Class PriorityQueueCopierWrapper.BatchMerger

java.lang.Object

org.apache.drill.exec.physical.impl.xsort.PriorityQueueCopierWrapper.BatchMerger

All Implemented Interfaces:

AutoCloseable, SortImpl.SortResults

Enclosing class:

PriorityQueueCopierWrapper

public static class PriorityQueueCopierWrapper.BatchMerger
extends Object
implements SortImpl.SortResults, AutoCloseable

We've gathered a set of batches, each of which has been sorted. The batches may have passed through a filter and thus may have "holes" where rows have been filtered out. We will spill records in blocks of targetRecordCount. To prepare, copy that many records into an outputContainer as a set of contiguous values in new vectors. The result is a single batch with vectors that combine a collection of input batches up to the given threshold.

Input. Here the top line is a selection vector of indexes. The second line is a set of batch groups (separated by underscores) with letters indicating individual records:

 [3 7 4 8 0 6 1] [5 3 6 8 2 0]
 [eh_ad_ibf]     [r_qm_kn_p]

Output, assuming blocks of 5 records. The brackets represent batches, the line represents the set of batches copied to the spill file.

 [abcde] [fhikm] [npqr]

The copying operation does a merge as well: copying values from the sources in ordered fashion. Consider a different example, we want to merge two input batches to produce a single output batch:

 Input:  [aceg] [bdfh]
 Output: [abcdefgh]

In the above, the input consists of two sorted batches. (In reality, the input batches have an associated selection vector, but that is omitted here and just the sorted values shown.) The output is a single batch with the merged records (indicated by letters) from the two input batches.

Here we bind the copier to the batchGroupList of sorted, buffered batches to be merged. We bind the copier output to outputContainer: the copier will write its merged "batches" of records to that container.

Calls to the next() method sequentially return merged batches of the desired row count.

Method Summary

Modifier and Type	Method	Description
void	close()
int	getBatchCount()
VectorContainer	getContainer()	Container into which results are delivered.
long	getEstBatchSize()	Gets the estimated batch size, in bytes.
int	getRecordCount()
SelectionVector2	getSv2()
SelectionVector4	getSv4()
boolean	next()	Read the next merged batch.
void	updateOutputContainer(VectorContainer container, SelectionVector4 sv4, RecordBatch.IterOutcome outcome, BatchSchema schema)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

next

public boolean next()

Read the next merged batch. The batch holds the specified row count, but may be less if this is the last batch.

Specified by:

next in interface SortImpl.SortResults

Returns:

the number of rows in the batch, or 0 if no more batches are available

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface SortImpl.SortResults

getRecordCount

public int getRecordCount()

Specified by:

getRecordCount in interface SortImpl.SortResults

getBatchCount

public int getBatchCount()

Specified by:

getBatchCount in interface SortImpl.SortResults

getEstBatchSize

public long getEstBatchSize()

Gets the estimated batch size, in bytes. Use for estimating the memory needed to process the batches that this operator created.

Returns:

the size of the largest batch created by this operation, in bytes

getSv4

public SelectionVector4 getSv4()

Specified by:

getSv4 in interface SortImpl.SortResults

updateOutputContainer

public void updateOutputContainer(VectorContainer container,
 SelectionVector4 sv4,
 RecordBatch.IterOutcome outcome,
 BatchSchema schema)

Specified by:

updateOutputContainer in interface SortImpl.SortResults

getSv2

public SelectionVector2 getSv2()

Specified by:

getSv2 in interface SortImpl.SortResults

getContainer

public VectorContainer getContainer()

Description copied from interface: SortImpl.SortResults

Container into which results are delivered. May the the original operator container, or may be a different one. This is the container that should be sent downstream. This is a fixed value for all returned results.

Specified by:

getContainer in interface SortImpl.SortResults

Returns: