org.apache.druid.query.topn.types

Class NullableNumericTopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>

java.lang.Object

org.apache.druid.query.topn.types.NullableNumericTopNColumnAggregatesProcessor<Selector>

All Implemented Interfaces:

ColumnSelectorStrategy, TopNColumnAggregatesProcessor<Selector>

Direct Known Subclasses:

DoubleTopNColumnAggregatesProcessor, FloatTopNColumnAggregatesProcessor, LongTopNColumnAggregatesProcessor

public abstract class NullableNumericTopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>
extends Object
implements TopNColumnAggregatesProcessor<Selector>

Base TopNColumnAggregatesProcessor for BaseNullableColumnValueSelector. Non-null selector values aggregates are stored in a type appropriate primitive map, created by TopNColumnAggregatesProcessor.initAggregateStore() and available via getAggregatesStore(), and null valued row aggregates are stored in a separate nullValueAggregates Aggregator array. updateResults(org.apache.druid.query.topn.TopNResultBuilder) will combine both the map and null aggregates to populate the TopNResultBuilder with the values produced by scanAndAggregate(org.apache.druid.query.topn.TopNQuery, Selector, org.apache.druid.segment.Cursor, org.apache.druid.query.aggregation.Aggregator[][]).

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	NullableNumericTopNColumnAggregatesProcessor(Function<Object,Comparable<?>> converter)

Method Summary

Modifier and Type	Method and Description
void	closeAggregators() Closes all on heap Aggregator associated withe the aggregates processor
int	getCardinality(Selector selector) Get value cardinality of underlying ColumnValueSelector
Aggregator[][]	getRowSelector(TopNQuery query, TopNParams params, StorageAdapter storageAdapter) Used by HeapBasedTopNAlgorithm.
long	scanAndAggregate(TopNQuery query, Selector selector, Cursor cursor, Aggregator[][] rowSelector) Used by HeapBasedTopNAlgorithm.
void	updateResults(TopNResultBuilder resultBuilder) Used by HeapBasedTopNAlgorithm.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.druid.query.topn.types.TopNColumnAggregatesProcessor

initAggregateStore

Constructor Detail

NullableNumericTopNColumnAggregatesProcessor

protected NullableNumericTopNColumnAggregatesProcessor(Function<Object,Comparable<?>> converter)

Method Detail

getCardinality

public int getCardinality(Selector selector)

Description copied from interface: TopNColumnAggregatesProcessor

Get value cardinality of underlying ColumnValueSelector

Specified by:

getCardinality in interface TopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>

getRowSelector

public Aggregator[][] getRowSelector(TopNQuery query,
                                     TopNParams params,
                                     StorageAdapter storageAdapter)

Description copied from interface: TopNColumnAggregatesProcessor

Used by HeapBasedTopNAlgorithm. Create an Aggregator[][] using BaseTopNAlgorithm.AggregatorArrayProvider and the given parameters. As the Aggregator[][] is used as an integer-based lookup, this method is only applicable for dimension types that use integer row values, e.g. string columns where the value cardinality is known. A dimension type that does not have integer values should return null.

Specified by:

getRowSelector in interface TopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>

Parameters:

query - The TopN query being served

params - Parameters for the TopN query being served

storageAdapter - Column storage adapter, to provide information about the column that can be used for query optimization, e.g. whether dimension values are sorted or not

Returns:

an Aggregator[][] for integer-valued dimensions, null otherwise

scanAndAggregate

public long scanAndAggregate(TopNQuery query,
                             Selector selector,
                             Cursor cursor,
                             Aggregator[][] rowSelector)

Description copied from interface: TopNColumnAggregatesProcessor

Used by HeapBasedTopNAlgorithm. The contract of this method requires calling TopNColumnAggregatesProcessor.initAggregateStore() prior to calling this method. Iterate through the Cursor, reading the current row from a dimension value selector, and for each row value: 1. Retrieve the Aggregator[] for the row value from rowSelector (fast integer lookup), usable if value cardinality is known, or from aggregatesStore (slower map). 2. If the rowSelector/aggregatesStore did not have an entry for a particular row value, this function should retrieve the current Aggregator[] using BaseTopNAlgorithm.makeAggregators(org.apache.druid.segment.Cursor, java.util.List<org.apache.druid.query.aggregation.AggregatorFactory>) and the provided cursor and query, storing them in rowSelector/aggregatesStore 3. Call Aggregator.aggregate() on each of the aggregators. If a dimension type doesn't have integer values, it should ignore rowSelector and use the aggregatesStore map only.

Specified by:

scanAndAggregate in interface TopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>

Parameters:

query - The TopN query being served.

selector - Dimension value selector

cursor - Cursor for the segment being queried

rowSelector - Integer lookup containing aggregators

Returns:

the number of processed rows (after postFilters are applied inside the cursor being processed)

updateResults

public void updateResults(TopNResultBuilder resultBuilder)

Description copied from interface: TopNColumnAggregatesProcessor

Used by HeapBasedTopNAlgorithm. Read entries from the aggregates store, adding the keys and associated values to the resultBuilder, applying the valueTransformer to the keys if present

Specified by:

updateResults in interface TopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>

Parameters:

resultBuilder - TopN result builder

closeAggregators

public void closeAggregators()

Description copied from interface: TopNColumnAggregatesProcessor

Closes all on heap Aggregator associated withe the aggregates processor

Specified by:

closeAggregators in interface TopNColumnAggregatesProcessor<Selector extends BaseNullableColumnValueSelector>