org.apache.druid.query

Class TableDataSource

java.lang.Object

org.apache.druid.query.TableDataSource

All Implemented Interfaces:

DataSource

Direct Known Subclasses:

GlobalTableDataSource

public class TableDataSource
extends Object
implements DataSource

Constructor Summary

Constructors

Constructor and Description
TableDataSource(String name)

Method Summary

Modifier and Type	Method and Description
static TableDataSource	create(String name)
boolean	equals(Object o)
List<DataSource>	getChildren() Returns datasources that this datasource depends on.
String	getName()
Set<String>	getTableNames() Returns the names of all table datasources involved in this query.
int	hashCode()
boolean	isCacheable() 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.

Methods inherited from class java.lang.Object

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

Constructor Detail

TableDataSource

public TableDataSource(String name)

Method Detail

create

public static TableDataSource create(String name)

getName

public String getName()

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

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()

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 modify the behavior of per-segment processing are not cacheable (like 'join'). Nor are dataSources that do not actually reference segments (like 'inline'), since cache keys are always based on segment identifiers. Note: Ideally, queries on 'join' datasources _would_ be cacheable, but we cannot currently do this due to lacking the code necessary to compute cache keys properly.

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

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object