Package com.mckoi.database

Class QueryPlan.RangeSelectNode

java.lang.Object

com.mckoi.database.QueryPlan.SingleQueryPlanNode

com.mckoi.database.QueryPlan.RangeSelectNode

All Implemented Interfaces:

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

Enclosing class:

QueryPlan

public static class QueryPlan.RangeSelectNode
extends QueryPlan.SingleQueryPlanNode

The node for performing a simple indexed query on a single column of the child node. Finds the set from the child node that matches the range.

The given Expression object must conform to a number of rules. It may reference only one column in the child node. It must consist of only simple mathemetical and logical operators (<, >, =, <>, >=, <=, AND, OR). The left side of each mathematical operator must be a variable, and the right side must be a constant (parameter subsitution or correlated value). For example; (col > 10 AND col < 100) OR col > 1000 OR col == 10

Breaking any of these rules will mean the range select can not happen.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private Expression	expression	A simple expression that represents the range to select.
(package private) static long	serialVersionUID

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

child

Constructor Summary

Constructors

Constructor	Description
RangeSelectNode(QueryPlanNode child, Expression exp)

Method Summary

Modifier and Type	Method	Description
private void	calcRange(QueryContext context, DataTableColumnDef field, SelectableRangeSet range, Expression exp)	Calculates a list of SelectableRange objects that represent the range of the expression.
java.lang.Object	clone()	Deep clone.
private java.util.ArrayList	createAndList(java.util.ArrayList list, Expression exp)	Given an Expression, this will return a list of expressions that can be safely executed as a set of 'and' operations.
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 child.
Table	evaluate(QueryContext context)	Evaluates the node and returns the result as a Table.
java.lang.String	titleString()
private void	updateRange(QueryContext context, SelectableRangeSet range, DataTableColumnDef field, Expression e)	Updates a range with the given expression.

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

child, debugString

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

static final long serialVersionUID

See Also:

Constant Field Values

expression

private Expression expression

A simple expression that represents the range to select. See the class comments for a description for how this expression must be formed.

Constructor Detail

RangeSelectNode

public RangeSelectNode(QueryPlanNode child,
                       Expression exp)

Method Detail

createAndList

private java.util.ArrayList createAndList(java.util.ArrayList list,
                                          Expression exp)

Given an Expression, this will return a list of expressions that can be safely executed as a set of 'and' operations. For example, an expression of 'a=9 and b=c and d=2' would return the list; 'a=9','b=c', 'd=2'.

If non 'and' operators are found then the reduction stops.

updateRange

private void updateRange(QueryContext context,
                         SelectableRangeSet range,
                         DataTableColumnDef field,
                         Expression e)

Updates a range with the given expression.

calcRange

private void calcRange(QueryContext context,
                       DataTableColumnDef field,
                       SelectableRangeSet range,
                       Expression exp)

Calculates a list of SelectableRange objects that represent the range of the expression.

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.SingleQueryPlanNode

Default implementation delegates responsibility to child.

Specified by:

discoverTableNames in interface QueryPlanNode

Overrides:

discoverTableNames in class QueryPlan.SingleQueryPlanNode

discoverCorrelatedVariables

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

Description copied from class: QueryPlan.SingleQueryPlanNode

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

Specified by:

discoverCorrelatedVariables in interface QueryPlanNode

Overrides:

discoverCorrelatedVariables in class QueryPlan.SingleQueryPlanNode

clone

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

Description copied from class: QueryPlan.SingleQueryPlanNode

Deep clone.

Specified by:

clone in interface QueryPlanNode

Overrides:

clone in class QueryPlan.SingleQueryPlanNode

Throws:

java.lang.CloneNotSupportedException

titleString

public java.lang.String titleString()

Overrides:

titleString in class QueryPlan.SingleQueryPlanNode