net.sf.farrago.fennel.rel
Class CalcRelSplitter

java.lang.Object
  net.sf.farrago.fennel.rel.CalcRelSplitter

Direct Known Subclasses:

FarragoAutoCalcRule.AutoCalcRelSplitter, FarragoMultisetSplitterRule.MultisetRelSplitter, FarragoMultisetSplitterRule.NestedRelSplitter, WindowedAggSplitterRule.WindowedAggRelSplitter

public abstract class CalcRelSplitter
extends Object

CalcRelSplitter operates on a CalcRel with multiple RexCall sub-expressions that cannot all be implemented by a single concrete RelNode.

For example, the Java and Fennel calculator do not implement an identical set of operators. The CalcRel can be used to split a single CalcRel with mixed Java- and Fennel-only operators into a tree of CalcRel object that can each be individually implemented by either Java or Fennel.and splits it into several CalcRel instances.

Currently the splitter is only capable of handling two "rel types". That is, it can deal with Java vs. Fennel CalcRels, but not Java vs. Fennel vs. some other type of CalcRel.

See FarragoAutoCalcRule for an example of how this class is used.

Nested Class Summary

private static class	CalcRelSplitter.CannotImplement Control exception for CalcRelSplitter.ImplementTester.
private static class	CalcRelSplitter.HighestUsageFinder Builds an array of the highest level which contains an expression which uses each expression as an input.
private static class	CalcRelSplitter.ImplementTester Visitor which returns whether an expression can be implemented in a given type of relational expression.
private static class	CalcRelSplitter.InputToCommonExprConverter Shuttle which converts every reference to an input field in an expression to a reference to a common sub-expression.
private static class	CalcRelSplitter.MaxInputFinder Finds the highest level used by any of the inputs of a given expression.
static class	CalcRelSplitter.RelType

Field Summary

private RelNode	child
private RelOptCluster	cluster
private RexProgram	program
private CalcRelSplitter.RelType[]	relTypes
private static Logger	ruleTracer
private RelTraitSet	traits
private RelDataTypeFactory	typeFactory

Constructor Summary

CalcRelSplitter(CalcRel calc, CalcRelSplitter.RelType[] relTypes)
Constructs a CalcRelSplitter.

Method Summary

protected boolean	canImplement(CalcRel rel, String relTypeName) Returns whether a relational expression can be implemented solely in a given CalcRelSplitter.RelType.
private int	chooseLevels(RexNode[] exprs, int conditionOrdinal, int[] exprLevels, int[] levelTypeOrdinals) Figures out which expressions to calculate at which level.
private static int	count(boolean[] booleans) Returns the number of bits set in an array.
private RexProgram	createProgramForLevel(int level, RelDataType inputRowType, RexNode[] allExprs, int[] exprLevels, int[] inputExprOrdinals, int[] projectExprOrdinals, int conditionExprOrdinal, RelDataType outputRowType) Creates a program containing the expressions for a given level.
(package private) RelNode	execute()
private static int	firstSet(boolean[] booleans) Returns the index of the first set bit in an array.
private int[]	identityArray(int length)
private static int	indexOf(int value, int[] map) Searches for a value in a map, and returns the position where it was found, or -1.
private void	traceLevelExpressions(RexNode[] exprs, int[] exprLevels, int[] levelTypeOrdinals, int levelCount) Traces the given array of level expression lists at the finer level.

Methods inherited from class java.lang.Object

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

Field Detail

ruleTracer

private static final Logger ruleTracer

program

private final RexProgram program

typeFactory

private final RelDataTypeFactory typeFactory

relTypes

private final CalcRelSplitter.RelType[] relTypes

cluster

private final RelOptCluster cluster

traits

private final RelTraitSet traits

child

private final RelNode child

Constructor Detail

CalcRelSplitter

CalcRelSplitter(CalcRel calc,
                CalcRelSplitter.RelType[] relTypes)

Constructs a CalcRelSplitter.

Parameters:

calc - CalcRel to split

relTypes - Array of rel types, e.g. {Java, Fennel}. Must be distinct.

Method Detail

execute

RelNode execute()

chooseLevels

private int chooseLevels(RexNode[] exprs,
                         int conditionOrdinal,
                         int[] exprLevels,
                         int[] levelTypeOrdinals)

Figures out which expressions to calculate at which level.

Parameters:

exprs - Array of expressions

conditionOrdinal - Ordinal of the condition expression, or -1 if no condition

exprLevels - Level ordinal for each expression (output)

levelTypeOrdinals - The type of each level (output)

identityArray

private int[] identityArray(int length)

createProgramForLevel

private RexProgram createProgramForLevel(int level,
                                         RelDataType inputRowType,
                                         RexNode[] allExprs,
                                         int[] exprLevels,
                                         int[] inputExprOrdinals,
                                         int[] projectExprOrdinals,
                                         int conditionExprOrdinal,
                                         RelDataType outputRowType)

Creates a program containing the expressions for a given level.

The expression list of the program will consist of all entries in the expression list allExprs[i] for which the corresponding level ordinal exprLevels[i] is equal to level. Expressions are mapped according to inputExprOrdinals.

Parameters:

level - Level ordinal

inputRowType - Input row type

allExprs - Array of all expressions

exprLevels - Array of the level ordinal of each expression

inputExprOrdinals - Ordinals in the expression list of input expressions. Input expression i will be found at position inputExprOrdinals[i].

projectExprOrdinals - Ordinals of the expressions to be output this level.

conditionExprOrdinal - Ordinal of the expression to form the condition for this level, or -1 if there is no condition.

outputRowType - Output row type

Returns:

Relational expression

traceLevelExpressions

private void traceLevelExpressions(RexNode[] exprs,
                                   int[] exprLevels,
                                   int[] levelTypeOrdinals,
                                   int levelCount)

Traces the given array of level expression lists at the finer level.

Parameters:

exprs - Array expressions

exprLevels - For each expression, the ordinal of its level

levelTypeOrdinals - For each level, the ordinal of its reltype in the relTypes array

levelCount - The number of levels

count

private static int count(boolean[] booleans)

Returns the number of bits set in an array.

firstSet

private static int firstSet(boolean[] booleans)

Returns the index of the first set bit in an array.

indexOf

private static int indexOf(int value,
                           int[] map)

Searches for a value in a map, and returns the position where it was found, or -1.

Parameters:

value - Value to search for

map - Map to search in

Returns:

Ordinal of value in map, or -1 if not found

canImplement

protected boolean canImplement(CalcRel rel,
                               String relTypeName)

Returns whether a relational expression can be implemented solely in a given CalcRelSplitter.RelType.

Parameters:

rel - Calculation relational expression

relTypeName - Name of a CalcRelSplitter.RelType

Returns:

Whether relational expression can be implemented