net.sf.farrago.fennel.rel
Class FennelReshapeRule

java.lang.Object
  org.eigenbase.relopt.RelOptRule
      net.sf.farrago.fennel.rel.FennelReshapeRule

public class FennelReshapeRule
extends RelOptRule

FennelReshapeRule is a rule that converts a CalcRel into a FennelReshapeRel, provided the CalcRel only references simple projections and contains a simple condition, if it has a condition.

The projection is simple if it consists of only RexInputRefs or CASTs of RexInputRefs where the cast effectively does not require any actual data conversion or data validation.

The condition is simple if the expression is an AND of filters, where each filter is of the form RexInputRef OP RexLiteral. Each RexInputRef can only be referenced once, and OP is either =, >, >=, <, or <=. However, the non-equality operators can only be referenced once.

Version:

$Id: //open/dev/farrago/src/net/sf/farrago/fennel/rel/FennelReshapeRule.java#3 $

Author:

Zelaine Fong

Field Summary

static FennelReshapeRule

instance

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

FennelReshapeRule() Creates a FennelReshapeRule.

Method Summary

CallingConvention	getOutConvention() Returns the calling convention of the result of firing this rule, null if not known.
private boolean	isCastSimple(RelDataType origType, RelDataType castType) Returns true if a type is a simple cast of another type.
private boolean	isConditionSimple(CalcRel calcRel, RexNode filterExprs, List<Integer> filterList, List<RexLiteral> literals, List<CompOperatorEnum> op) Determines if a filter condition is a simple one and returns the parameters corresponding to the simple filters.
private RelDataType	isProjectSimple(CalcRel calcRel, List<Integer> projOrdinals) Determines if a projection is simple.
void	onMatch(RelOptRuleCall call) Receives notification about a rule match.

Methods inherited from class org.eigenbase.relopt.RelOptRule

convert, equals, equals, getOperand, getOperands, getOutTrait, hashCode, matches, mergeTraitsAndConvert, mergeTraitsAndConvert, toString

Methods inherited from class java.lang.Object

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

Field Detail

instance

public static final FennelReshapeRule instance

Constructor Detail

FennelReshapeRule

private FennelReshapeRule()

Creates a FennelReshapeRule.

Method Detail

getOutConvention

public CallingConvention getOutConvention()

Description copied from class: RelOptRule

Returns the calling convention of the result of firing this rule, null if not known.

Overrides:

getOutConvention in class RelOptRule

onMatch

public void onMatch(RelOptRuleCall call)

Description copied from class: RelOptRule

Receives notification about a rule match. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.

Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back RelOptRuleCall.transformTo(org.eigenbase.rel.RelNode) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)

isProjectSimple

private RelDataType isProjectSimple(CalcRel calcRel,
                                    List<Integer> projOrdinals)

Determines if a projection is simple.

Parameters:

calcRel - CalcRel containing the projection

projOrdinals - if the projection is simple, returns the ordinals of the projection inputs

Returns:

rowtype corresponding to the projection, provided it is simple; otherwise null is returned

isCastSimple

private boolean isCastSimple(RelDataType origType,
                             RelDataType castType)

Returns true if a type is a simple cast of another type. It is if the cast type is nullable and the cast is one of the following:

x TO x

char(n) TO varchar(m)

varchar(n) TO varchar(m)

x not null TO x nullable

Parameters:

origType - original type passed into the cast operand

castType - type the operand will be casted to

Returns:

true if the cast is simple

isConditionSimple

private boolean isConditionSimple(CalcRel calcRel,
                                  RexNode filterExprs,
                                  List<Integer> filterList,
                                  List<RexLiteral> literals,
                                  List<CompOperatorEnum> op)

Determines if a filter condition is a simple one and returns the parameters corresponding to the simple filters.

Parameters:

calcRel - original CalcRel

filterExprs - filter expression being analyzed

filterList - returns the list of filter ordinals in the simple expression

literals - returns the list of literals to be used in the simple comparisons

op - returns the operator to be used in the simple comparison

Returns:

true if the filter condition is simple