Package com.mckoi.database

Class QueryPlan.JoinNode

java.lang.Object

com.mckoi.database.QueryPlan.BranchQueryPlanNode

com.mckoi.database.QueryPlan.JoinNode

All Implemented Interfaces:

QueryPlanNode, java.io.Serializable, java.lang.Cloneable

Enclosing class:

QueryPlan

public static class QueryPlan.JoinNode
extends QueryPlan.BranchQueryPlanNode

A branch node for a non-equi join between two tables.

NOTE: The cost of a LeftJoin is higher if the right child result is greater than the left child result. The plan should be arranged so smaller results are on the left.

See Also:

Serialized Form

Field Summary

Fields inherited from class com.mckoi.database.QueryPlan.BranchQueryPlanNode

left, right

Constructor Summary

Constructors

Constructor	Description
JoinNode(QueryPlanNode left, QueryPlanNode right, Variable left_var, Operator join_op, Expression right_expression)

Method Summary

Modifier and Type	Method	Description
java.lang.Object	clone()	Deep clone.
java.util.ArrayList	discoverCorrelatedVariables(int level, java.util.ArrayList list)	Default implementation that discovers correlated variables for the given offset level.
java.util.ArrayList	discoverTableNames(java.util.ArrayList list)	Default implementation delegates responsibility to children.
Table	evaluate(QueryContext context)	Evaluates the node and returns the result as a Table.
java.lang.String	titleString()

Methods inherited from class java.lang.Object

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

Methods inherited from class com.mckoi.database.QueryPlan.BranchQueryPlanNode

debugString, left, right

Constructor Detail

JoinNode

public JoinNode(QueryPlanNode left,
                QueryPlanNode right,
                Variable left_var,
                Operator join_op,
                Expression right_expression)

Method Detail

evaluate

public Table evaluate(QueryContext context)

Description copied from interface: QueryPlanNode

Evaluates the node and returns the result as a Table. The VariableResolver resolves any outer variables

discoverTableNames

public java.util.ArrayList discoverTableNames(java.util.ArrayList list)

Description copied from class: QueryPlan.BranchQueryPlanNode

Default implementation delegates responsibility to children.

Specified by:

discoverTableNames in interface QueryPlanNode

Overrides:

discoverTableNames in class QueryPlan.BranchQueryPlanNode

discoverCorrelatedVariables

public java.util.ArrayList discoverCorrelatedVariables(int level,
                                                       java.util.ArrayList list)

Description copied from class: QueryPlan.BranchQueryPlanNode

Default implementation that discovers correlated variables for the given offset level.

Specified by:

discoverCorrelatedVariables in interface QueryPlanNode

Overrides:

discoverCorrelatedVariables in class QueryPlan.BranchQueryPlanNode

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException

Description copied from class: QueryPlan.BranchQueryPlanNode

Deep clone.

Specified by:

clone in interface QueryPlanNode

Overrides:

clone in class QueryPlan.BranchQueryPlanNode

Throws:

java.lang.CloneNotSupportedException

titleString

public java.lang.String titleString()

Overrides:

titleString in class QueryPlan.BranchQueryPlanNode