org.apache.druid.query.groupby.epinephelinae

Class GroupByQueryEngineV2

java.lang.Object

org.apache.druid.query.groupby.epinephelinae.GroupByQueryEngineV2

public class GroupByQueryEngineV2
extends Object

Class that knows how to process a groupBy query on a single StorageAdapter. It returns a Sequence of ResultRow objects that are not guaranteed to be in any particular order, and may not even be fully grouped. It is expected that a downstream GroupByMergingQueryRunnerV2 will finish grouping these results. This code runs on data servers, like Historicals. Used by GroupByStrategyV2.process(GroupByQuery, StorageAdapter, GroupByQueryMetrics).

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GroupByQueryEngineV2.GroupByEngineIterator<KeyType>
static class	GroupByQueryEngineV2.HashAggregateIterator

Field Summary

Fields

Modifier and Type	Field and Description
static org.apache.druid.query.groupby.epinephelinae.GroupByQueryEngineV2.GroupByStrategyFactory	STRATEGY_FACTORY

Method Summary

Modifier and Type	Method and Description
static boolean	canPushDownLimit(ColumnSelectorFactory columnSelectorFactory, String columnName) check if a column will operate correctly with LimitedBufferHashGrouper for query limit pushdown
static void	convertRowTypesToOutputTypes(List<DimensionSpec> dimensionSpecs, ResultRow resultRow, int resultRowDimensionStart)
static GroupByColumnSelectorPlus[]	createGroupBySelectorPlus(ColumnSelectorPlus<GroupByColumnSelectorStrategy>[] baseSelectorPlus, int dimensionStart)
static int	getCardinalityForArrayAggregation(GroupByQueryConfig querySpecificConfig, GroupByQuery query, StorageAdapter storageAdapter, ByteBuffer buffer) Returns the cardinality of array needed to do array-based aggregation, or -1 if array-based aggregation is impossible.
static boolean	hasNoExplodingDimensions(ColumnInspector inspector, List<DimensionSpec> dimensions) Checks whether all "dimensions" are either single-valued, or if the input column or output dimension spec has specified a type that TypeSignature.isArray().
static Sequence<ResultRow>	process(GroupByQuery query, StorageAdapter storageAdapter, NonBlockingPool<ByteBuffer> intermediateResultsBufferPool, GroupByQueryConfig querySpecificConfig, DruidProcessingConfig processingConfig, GroupByQueryMetrics groupByQueryMetrics)

Methods inherited from class java.lang.Object

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

Field Detail

STRATEGY_FACTORY

public static final org.apache.druid.query.groupby.epinephelinae.GroupByQueryEngineV2.GroupByStrategyFactory STRATEGY_FACTORY

Method Detail

createGroupBySelectorPlus

public static GroupByColumnSelectorPlus[] createGroupBySelectorPlus(ColumnSelectorPlus<GroupByColumnSelectorStrategy>[] baseSelectorPlus,
                                                                    int dimensionStart)

process

public static Sequence<ResultRow> process(GroupByQuery query,
                                          @Nullable
                                          StorageAdapter storageAdapter,
                                          NonBlockingPool<ByteBuffer> intermediateResultsBufferPool,
                                          GroupByQueryConfig querySpecificConfig,
                                          DruidProcessingConfig processingConfig,
                                          @Nullable
                                          GroupByQueryMetrics groupByQueryMetrics)

getCardinalityForArrayAggregation

public static int getCardinalityForArrayAggregation(GroupByQueryConfig querySpecificConfig,
                                                    GroupByQuery query,
                                                    StorageAdapter storageAdapter,
                                                    ByteBuffer buffer)

Returns the cardinality of array needed to do array-based aggregation, or -1 if array-based aggregation is impossible.

hasNoExplodingDimensions

public static boolean hasNoExplodingDimensions(ColumnInspector inspector,
                                               List<DimensionSpec> dimensions)

Checks whether all "dimensions" are either single-valued, or if the input column or output dimension spec has specified a type that TypeSignature.isArray(). Both cases indicate we don't want to explode the under-lying multi value column. Since selectors on non-existent columns will show up as full of nulls, they are effectively single valued, however capabilites on columns can also be null, for example during broker merge with an 'inline' datasource subquery, so we only return true from this method when capabilities are fully known.

convertRowTypesToOutputTypes

public static void convertRowTypesToOutputTypes(List<DimensionSpec> dimensionSpecs,
                                                ResultRow resultRow,
                                                int resultRowDimensionStart)

canPushDownLimit

public static boolean canPushDownLimit(ColumnSelectorFactory columnSelectorFactory,
                                       String columnName)

check if a column will operate correctly with LimitedBufferHashGrouper for query limit pushdown