org.apache.druid.query

Class UnionDataSource

java.lang.Object

org.apache.druid.query.UnionDataSource

All Implemented Interfaces:

DataSource

public class UnionDataSource
extends Object
implements DataSource

Constructor Summary

Constructors

Constructor and Description
UnionDataSource(List<TableDataSource> dataSources)

Method Summary

Modifier and Type	Method and Description
Function<SegmentReference,SegmentReference>	createSegmentMapFunction(Query query, AtomicLong cpuTime) Returns a segment function on to how to segment should be modified.
boolean	equals(Object o)
byte[]	getCacheKey() Compute a cache key prefix for a data source.
List<DataSource>	getChildren() Returns datasources that this datasource depends on.
List<TableDataSource>	getDataSources()
Set<String>	getTableNames() Returns the names of all table datasources involved in this query.
int	hashCode()
boolean	isCacheable(boolean isBroker) Returns true if queries on this dataSource are cacheable at both the result level and per-segment level.
boolean	isConcrete() Returns true if this datasource represents concrete data that can be scanned via a Segment adapter of some kind.
boolean	isGlobal() Returns true if all servers have a full copy of this datasource.
String	toString()
DataSource	withChildren(List<DataSource> children) Return a new DataSource, identical to this one, with different children.
DataSource	withUpdatedDataSource(DataSource newSource) Returns an updated datasource based on the specified new source.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

UnionDataSource

public UnionDataSource(List<TableDataSource> dataSources)

Method Detail

getTableNames

public Set<String> getTableNames()

Description copied from interface: DataSource

Returns the names of all table datasources involved in this query. Does not include names for non-tables, like lookups or inline datasources.

Specified by:

getTableNames in interface DataSource

getDataSources

public List<TableDataSource> getDataSources()

getChildren

public List<DataSource> getChildren()

Description copied from interface: DataSource

Returns datasources that this datasource depends on. Will be empty for leaf datasources like 'table'.

Specified by:

getChildren in interface DataSource

withChildren

public DataSource withChildren(List<DataSource> children)

Description copied from interface: DataSource

Return a new DataSource, identical to this one, with different children. The number of children must be equal to the number of children that this datasource already has.

Specified by:

withChildren in interface DataSource

isCacheable

public boolean isCacheable(boolean isBroker)

Description copied from interface: DataSource

Returns true if queries on this dataSource are cacheable at both the result level and per-segment level. Currently, dataSources that do not actually reference segments (like 'inline'), are not cacheable since cache keys are always based on segment identifiers.

Specified by:

isCacheable in interface DataSource

isGlobal

public boolean isGlobal()

Description copied from interface: DataSource

Returns true if all servers have a full copy of this datasource. True for things like inline, lookup, etc, or for queries of those. Currently this is coupled with joinability - if this returns true then the query engine expects there exists a JoinableFactory which might build a Joinable for this datasource directly. If a subquery 'inline' join is required to join this datasource on the right hand side, then this value must be false for now. In the future, instead of directly using this method, the query planner and engine should consider JoinableFactory.isDirectlyJoinable(DataSource) when determining if the right hand side is directly joinable, which would allow decoupling this property from joins.

Specified by:

isGlobal in interface DataSource

isConcrete

public boolean isConcrete()

Description copied from interface: DataSource

Returns true if this datasource represents concrete data that can be scanned via a Segment adapter of some kind. True for e.g. 'table' but not for 'query' or 'join'.

Specified by:

isConcrete in interface DataSource

See Also:

which uses this, which uses this

createSegmentMapFunction

public Function<SegmentReference,SegmentReference> createSegmentMapFunction(Query query,
                                                                            AtomicLong cpuTime)

Description copied from interface: DataSource

Returns a segment function on to how to segment should be modified.

Specified by:

createSegmentMapFunction in interface DataSource

Parameters:

query - the input query

cpuTime - the cpu time accumulator

Returns:

the segment function

withUpdatedDataSource

public DataSource withUpdatedDataSource(DataSource newSource)

Description copied from interface: DataSource

Returns an updated datasource based on the specified new source.

Specified by:

withUpdatedDataSource in interface DataSource

Parameters:

newSource - the new datasource to be used to update an existing query

Returns:

the updated datasource to be used

getCacheKey

public byte[] getCacheKey()

Description copied from interface: DataSource

Compute a cache key prefix for a data source. This includes the data sources that participate in the RHS of a join as well as any query specific constructs associated with join data source such as base table filter. This key prefix can be used in segment level cache or result level cache. The function can return following - Non-empty byte array - If there is join datasource involved and caching is possible. The result includes join condition expression, join type and cache key returned by joinable factory for each PreJoinableClause - NULL - There is a join but caching is not possible. It may happen if one of the participating datasource in the JOIN is not cacheable.

Specified by:

getCacheKey in interface DataSource

Returns:

the cache key to be used as part of query cache key

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object