org.apache.lens.cube.parse.join

Class JoinClause

java.lang.Object

org.apache.lens.cube.parse.join.JoinClause

All Implemented Interfaces:

Comparable<JoinClause>

public class JoinClause
extends Object
implements Comparable<JoinClause>

Constructor Summary

Constructors

Constructor and Description
JoinClause(CubeQueryContext cubeql, Map<Aliased<Dimension>,List<TableRelationship>> chain, Set<Dimension> dimsInPath)

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(JoinClause joinClause)
int	getCost()
Set<Dimension>	getDimsInPath()
JoinTree	getJoinTree()
JoinTree	mergeJoinChains(Map<Aliased<Dimension>,List<TableRelationship>> chain) Takes chains and merges them in the form of a tree.
String	toString()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

JoinClause

public JoinClause(CubeQueryContext cubeql,
          Map<Aliased<Dimension>,List<TableRelationship>> chain,
          Set<Dimension> dimsInPath)

Method Detail

getCost

public int getCost()

compareTo

public int compareTo(JoinClause joinClause)

Specified by:

compareTo in interface Comparable<JoinClause>

mergeJoinChains

public JoinTree mergeJoinChains(Map<Aliased<Dimension>,List<TableRelationship>> chain)

Takes chains and merges them in the form of a tree. If two chains have some common path till some table and bifurcate from there, then in the chain, both paths will have the common path but the resultant tree will have single path from root(cube) to that table and paths will bifurcate from there.

For example, citystate = [basecube.cityid=citydim.id], [citydim.stateid=statedim.id] cityzip = [basecube.cityid=citydim.id], [citydim.zipcode=zipdim.code]

Without merging, the behaviour is like this:

(basecube.cityid=citydim.id) (citydim.stateid=statedim.id) _____________________________citydim____________________________________statedim | basecube------| |_____________________________citydim____________________________________zipdim (basecube.cityid=citydim.id) (citydim.zipcode=zipdim.code)

Merging will result in a tree like following

(citydim.stateid=statedim.id)

________________________________ statedim (basecube.cityid=citydim.id) | basecube-------------------------------citydim---- | |________________________________ zipdim (citydim.zipcode=zipdim.code)

Doing this will reduce the number of joins wherever possible.

Parameters:

chain - Joins in Linear format.

Returns:

Joins in Tree format

toString

@Generated(value="lombok")
public String toString()

Overrides:

toString in class Object

getDimsInPath

@Generated(value="lombok")
public Set<Dimension> getDimsInPath()

getJoinTree

@Generated(value="lombok")
public JoinTree getJoinTree()