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, mondrian.rolap.RolapCube, mondrian.rolap.aggmatcher.AggStar, mondrian.rolap.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) is required to join the fact table for the levels table.

Since:

Nov 11, 2005

Author:

av

Nested Class Summary

(package private) static class

SqlTupleReader.WhichSelect Description of the position of a SELECT statement in a UNION.

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

TupleReader.MemberBuilder

Field Summary

protected TupleConstraint	constraint
(package private) int	maxRows
(package private) List<mondrian.rolap.SqlTupleReader.Target>	targets

Constructor Summary

SqlTupleReader(TupleConstraint constraint)

Method Summary

void	addLevelMembers(RolapLevel level, TupleReader.MemberBuilder memberBuilder, List<RolapMember> srcMembers) Adds a hierarchy to retrieve members from.
Object	getCacheKey() Returns an object that uniquely identifies the Result that this TupleReader would return.
int	getEnumTargetCount()
(package private) int	getMaxRows()
protected void	prepareTuples(DataSource dataSource, List<List<RolapMember>> partialResult, List<List<RolapMember>> newPartialResult)
List<RolapMember>	readMembers(DataSource dataSource, List<List<RolapMember>> partialResult, List<List<RolapMember>> newPartialResult) Performs the read.
List<RolapMember[]>	readTuples(DataSource jdbcConnection, List<List<RolapMember>> partialResult, List<List<RolapMember>> newPartialResult) Performs the read.
(package private) void	setMaxRows(int maxRows)

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

targets

List<mondrian.rolap.SqlTupleReader.Target> targets

maxRows

int maxRows

Constructor Detail

SqlTupleReader

public SqlTupleReader(TupleConstraint constraint)

Method Detail

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

getEnumTargetCount

public int getEnumTargetCount()

Returns:

number of targets that contain enumerated sets with calculated members

prepareTuples

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

readMembers

public List<RolapMember> readMembers(DataSource dataSource,
                                     List<List<RolapMember>> 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

readTuples

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

Description copied from interface: TupleReader

Performs the read.

Specified by:

readTuples in interface TupleReader

Returns:

a list of RolapMember[]

getMaxRows

int getMaxRows()

setMaxRows

void setMaxRows(int maxRows)