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

(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<TargetBase>	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.
protected void	addLevelMemberSql(SqlQuery sqlQuery, RolapLevel level, RolapCube baseCube, SqlTupleReader.WhichSelect whichSelect, AggStar aggStar) Generates the SQL statement to access members of level.
(package private) AggStar	chooseAggStar(TupleConstraint constraint, Evaluator evaluator) Obtains the AggStar instance which corresponds to an aggregate table which can be used to support the member constraint.
(package private) Pair<String,List<SqlStatement.Type>>	generateSelectForLevels(DataSource dataSource, RolapCube baseCube, SqlTupleReader.WhichSelect whichSelect) Generates the SQL string corresponding to the levels referenced.
(package private) Collection<RolapCube>	getBaseCubeCollection(Query query)
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.
(package private) int	getMaxRows()
(package private) Pair<String,List<SqlStatement.Type>>	makeLevelMembersSql(DataSource dataSource)
protected void	prepareTuples(DataSource dataSource, TupleList partialResult, List<List<RolapMember>> newPartialResult)
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.
(package private) void	setMaxRows(int maxRows)
(package private) Pair<String,List<SqlStatement.Type>>	sqlForEmptyTuple(DataSource dataSource, Collection<RolapCube> baseCubes)
(package private) boolean	targetIsOnBaseCube(TargetBase target, RolapCube baseCube)

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<TargetBase> 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

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)

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

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

makeLevelMembersSql

Pair<String,List<SqlStatement.Type>> makeLevelMembersSql(DataSource dataSource)

getBaseCubeCollection

Collection<RolapCube> getBaseCubeCollection(Query query)

sqlForEmptyTuple

Pair<String,List<SqlStatement.Type>> sqlForEmptyTuple(DataSource dataSource,
                                                      Collection<RolapCube> baseCubes)

generateSelectForLevels

Pair<String,List<SqlStatement.Type>> generateSelectForLevels(DataSource dataSource,
                                                             RolapCube baseCube,
                                                             SqlTupleReader.WhichSelect whichSelect)

Generates the SQL string corresponding to the levels referenced.

Parameters:

dataSource - jdbc connection that they query will execute against

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

whichSelect - Position of this select statement in a union

Returns:

SQL statement string and types

targetIsOnBaseCube

boolean targetIsOnBaseCube(TargetBase target,
                           RolapCube baseCube)

addLevelMemberSql

protected void addLevelMemberSql(SqlQuery sqlQuery,
                                 RolapLevel level,
                                 RolapCube baseCube,
                                 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

chooseAggStar

AggStar chooseAggStar(TupleConstraint constraint,
                      Evaluator evaluator)

Obtains the AggStar instance which corresponds to an aggregate table which can be used to support the member constraint.

Parameters:

constraint -

evaluator - the current evaluator to obtain the cube and members to be queried @return AggStar for aggregate table

getMaxRows

int getMaxRows()

setMaxRows

void setMaxRows(int maxRows)