mondrian.rolap

Class RolapNativeTopCount.TopCountConstraint

java.lang.Object

mondrian.rolap.SqlContextConstraint

mondrian.rolap.RolapNativeSet.SetConstraint

mondrian.rolap.RolapNativeTopCount.TopCountConstraint

All Implemented Interfaces:

MemberChildrenConstraint, SqlConstraint, TupleConstraint

Enclosing class:

RolapNativeTopCount

static class RolapNativeTopCount.TopCountConstraint
extends RolapNativeSet.SetConstraint

Field Summary

Fields

Modifier and Type	Field and Description
(package private) boolean	ascending
(package private) Exp	orderByExpr
(package private) Integer	topCount

Fields inherited from class mondrian.rolap.RolapNativeSet.SetConstraint

args

Constructor Summary

Constructors

Constructor and Description
TopCountConstraint(int count, CrossJoinArg[] args, RolapEvaluator evaluator, Exp orderByExpr, boolean ascending)

Method Summary

Modifier and Type	Method and Description
void	addConstraint(SqlQuery sqlQuery, RolapCube baseCube, AggStar aggStar) Called from LevelMembers: restricts the SQL resultset to the current context.
Object	getCacheKey() returns a key to cache the result
protected boolean	isJoinRequired() Returns whether a join with the fact table is required.
protected boolean	isValid() If the orderByExpr is not present than we're dealing with the 2 arg form of TC.
boolean	supportsAggTables()

Methods inherited from class mondrian.rolap.RolapNativeSet.SetConstraint

canApplyCrossJoinArgConstraint, getMemberChildrenConstraint

Methods inherited from class mondrian.rolap.SqlContextConstraint

addLevelConstraint, addMemberConstraint, addMemberConstraint, getEvaluator, isValidContext, isValidContext

Methods inherited from class java.lang.Object

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

Field Detail

orderByExpr

Exp orderByExpr

ascending

boolean ascending

topCount

Integer topCount

Constructor Detail

TopCountConstraint

public TopCountConstraint(int count,
                          CrossJoinArg[] args,
                          RolapEvaluator evaluator,
                          Exp orderByExpr,
                          boolean ascending)

Method Detail

isValid

protected boolean isValid()

If the orderByExpr is not present than we're dealing with the 2 arg form of TC. The 2 arg form cannot be evaluated with a join to the fact. Because of this, it's only valid to apply a native constraint for the 2 arg form if a single CJ arg is in place. Otherwise we'd need to join the dims together via the fact table, which could eliminate tuples that should be returned.

isJoinRequired

protected boolean isJoinRequired()

Returns whether a join with the fact table is required. A join is required if the context contains members from dimensions other than level. If we are interested in the members of a level or a members children then it does not make sense to join only one dimension (the one that contains the requested members) with the fact table for NON EMPTY optimization.

If there is a crossjoin, we need to join the fact table - even if the evaluator context is empty.

TopCount needs to join the fact table if a top count expression is present (i.e. orderByExpr). If not present than the results of TC should be the natural ordering of the set in the first argument, which cannot use a join to the fact table without potentially eliminating empty tuples.

Overrides:

isJoinRequired in class RolapNativeSet.SetConstraint

supportsAggTables

public boolean supportsAggTables()

Specified by:

supportsAggTables in interface TupleConstraint

Overrides:

supportsAggTables in class SqlContextConstraint

Returns:

true if the constraint can leverage an aggregate table

addConstraint

public void addConstraint(SqlQuery sqlQuery,
                          RolapCube baseCube,
                          AggStar aggStar)

Description copied from class: SqlContextConstraint

Called from LevelMembers: restricts the SQL resultset to the current context.

Specified by:

addConstraint in interface TupleConstraint

Overrides:

addConstraint in class RolapNativeSet.SetConstraint

Parameters:

sqlQuery - the query to modify

baseCube - base cube for virtual cube constraints

aggStar - aggregate star to use

getCacheKey

public Object getCacheKey()

Description copied from class: RolapNativeSet.SetConstraint

returns a key to cache the result

Specified by:

getCacheKey in interface SqlConstraint

Overrides:

getCacheKey in class RolapNativeSet.SetConstraint

Returns:

valid key or null to prevent the result from being cached