Package mondrian.rolap

Class SqlTupleReader

java.lang.Object

mondrian.rolap.SqlTupleReader

All Implemented Interfaces:

TupleReader

Direct Known Subclasses:

HighCardSqlTupleReader

public class SqlTupleReader
extends Object
implements TupleReader

Reads the members of a single level (level.members) or of multiple levels (crossjoin).

Allows the result to be restricted by a TupleConstraint. So the SqlTupleReader can also read Member.Descendants (which is level.members restricted to a common parent) and member.children (which is a special case of member.descendants). Other constraints, especially for the current slicer or evaluation context, are possible.

Caching

When a SqlTupleReader reads level.members, it groups the result into parent/children pairs and puts them into the cache. In order that these can be found later when the children of a parent are requested, a matching constraint must be provided for every parent.

• When reading members from a single level, then the constraint is not required to join the fact table in TupleConstraint.addLevelConstraint(mondrian.rolap.sql.SqlQuery, RolapCube, mondrian.rolap.aggmatcher.AggStar, RolapLevel) although it may do so to restrict the result. Also it is permitted to cache the parent/children from all members in MemberCache, so TupleConstraint.getMemberChildrenConstraint(RolapMember) should not return null.
• When reading multiple levels (i.e. we are performing a crossjoin), then we can not store the parent/child pairs in the MemberCache and TupleConstraint.getMemberChildrenConstraint(RolapMember) must return null. Also TupleConstraint.addConstraint(mondrian.rolap.sql.SqlQuery, mondrian.rolap.RolapCube, mondrian.rolap.aggmatcher.AggStar) is required to join the fact table for the levels table.

Since:

Nov 11, 2005

Author:

av

Nested Class Summary

Nested classes/interfaces inherited from interface mondrian.rolap.TupleReader

TupleReader.MemberBuilder

Field Summary

Fields

Modifier and Type	Field	Description
protected TupleConstraint	constraint

Constructor Summary

Constructors

Constructor	Description
SqlTupleReader(TupleConstraint constraint)

Method Summary

Modifier and Type	Method	Description
void	addLevelMembers(RolapLevel level, TupleReader.MemberBuilder memberBuilder, List<RolapMember> srcMembers)	Adds a hierarchy to retrieve members from.
protected void	addLevelMemberSql(SqlQuery sqlQuery, RolapLevel level, RolapCube baseCube, mondrian.rolap.SqlTupleReader.WhichSelect whichSelect, AggStar aggStar)	Generates the SQL statement to access members of level.
protected List<Member>	bumpNullMember(List<Member> members)
Object	getCacheKey()	Returns an object that uniquely identifies the Result that this TupleReader would return.
int	getEnumTargetCount()
protected Evaluator	getEvaluator(TupleConstraint constraint)	Obtains the evaluator used to find an aggregate table to support the Tuple constraint.
void	incrementEmptySets()	Indicates that there was an empty argument somewhere in the tuple.
boolean	isAllowHints()
protected void	prepareTuples(DataSource dataSource, TupleList partialResult, List<List<RolapMember>> newPartialResult, List<TargetBase> targetGroup)
TupleList	readMembers(DataSource dataSource, TupleList partialResult, List<List<RolapMember>> newPartialResult)	Performs the read.
TupleList	readTuples(DataSource jdbcConnection, TupleList partialResult, List<List<RolapMember>> newPartialResult)	Performs the read.
void	setAllowHints(boolean allowHints)

Methods inherited from class java.lang.Object

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

Field Detail

constraint

protected final TupleConstraint constraint

Constructor Detail

SqlTupleReader

public SqlTupleReader(TupleConstraint constraint)

Method Detail

isAllowHints

public boolean isAllowHints()

setAllowHints

public void setAllowHints(boolean allowHints)

incrementEmptySets

public void incrementEmptySets()

Description copied from interface: TupleReader

Indicates that there was an empty argument somewhere in the tuple.

Specified by:

incrementEmptySets in interface TupleReader

addLevelMembers

public void addLevelMembers(RolapLevel level,
                            TupleReader.MemberBuilder memberBuilder,
                            List<RolapMember> srcMembers)

Description copied from interface: TupleReader

Adds a hierarchy to retrieve members from.

Specified by:

addLevelMembers in interface TupleReader

Parameters:

level - level that the members correspond to

memberBuilder - used to build new members for this level

srcMembers - if set, array of enumerated members that make up this level

getCacheKey

public Object getCacheKey()

Description copied from interface: TupleReader

Returns an object that uniquely identifies the Result that this TupleReader would return. Clients may use this as a key for caching the result.

Specified by:

getCacheKey in interface TupleReader

Returns:

Cache key

getEnumTargetCount

public int getEnumTargetCount()

Returns:

number of targets that contain enumerated sets with calculated members

prepareTuples

protected void prepareTuples(DataSource dataSource,
                             TupleList partialResult,
                             List<List<RolapMember>> newPartialResult,
                             List<TargetBase> targetGroup)

readMembers

public TupleList readMembers(DataSource dataSource,
                             TupleList partialResult,
                             List<List<RolapMember>> newPartialResult)

Description copied from interface: TupleReader

Performs the read.

Specified by:

readMembers in interface TupleReader

Parameters:

dataSource - source for reading tuples

partialResult - partially cached result that should be used instead of executing sql query

newPartialResult - if non-null, return the result of the read; note that this is a subset of the full return list

Returns:

a list of RolapMember

bumpNullMember

protected List<Member> bumpNullMember(List<Member> members)

readTuples

public TupleList readTuples(DataSource jdbcConnection,
                            TupleList partialResult,
                            List<List<RolapMember>> newPartialResult)

Description copied from interface: TupleReader

Performs the read.

Specified by:

readTuples in interface TupleReader

Parameters:

jdbcConnection - Data source

partialResult - List of rows from previous pass

newPartialResult - Populated with a new list of rows

Returns:

a list of tuples

addLevelMemberSql

protected void addLevelMemberSql(SqlQuery sqlQuery,
                                 RolapLevel level,
                                 RolapCube baseCube,
                                 mondrian.rolap.SqlTupleReader.WhichSelect whichSelect,
                                 AggStar aggStar)

Generates the SQL statement to access members of level. For example,

SELECT "country", "state_province", "city"
 FROM "customer"
 GROUP BY "country", "state_province", "city", "init", "bar"
 ORDER BY "country", "state_province", "city"

accesses the "City" level of the "Customers" hierarchy. Note that:

• "country", "state_province" are the parent keys;
• "city" is the level key;
• "init", "bar" are member properties.

Parameters:

sqlQuery - the query object being constructed

level - level to be added to the sql query

baseCube - this is the cube object for regular cubes, and the underlying base cube for virtual cubes

whichSelect - describes whether this select belongs to a larger

aggStar - aggregate star if available

getEvaluator

protected Evaluator getEvaluator(TupleConstraint constraint)

Obtains the evaluator used to find an aggregate table to support the Tuple constraint.

Parameters:

constraint - Constraint

Returns:

evaluator for constraint