RolapStar (Pentaho Community Edition Project: mondrian 8.3.0.1-377 API)

java.lang.Object
- mondrian.rolap.RolapStar

```
public class RolapStar
extends Object
```
A RolapStar is a star schema. It is the means to read cell values.
todo: Move this class into a package that specializes in relational aggregation, doesn't know anything about hierarchies etc.

Since:

12 August, 2001

Author:

jhyde

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`RolapStar.AliasReplacer` Creates a copy of an expression, everywhere replacing one alias with another.
`static class`	`RolapStar.Bar` Temporary.
`static class`	`RolapStar.Column` A column in a star schema.
`static class`	`RolapStar.ColumnComparator` Comparator to compare columns based on their name and table that contains them
`static class`	`RolapStar.Condition`
`static class`	`RolapStar.Measure` Definition of a measure in a star schema.
`static class`	`RolapStar.Table` Definition of a table in a star schema.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addAggStar(AggStar aggStar)` Adds an `AggStar` to this star.
`protected MondrianDef.RelationOrJoin`	`cloneRelation(MondrianDef.Relation rel, String possibleName)`
`static void`	`collectColumns(Collection<RolapStar.Column> columnList, RolapStar.Table table, MondrianDef.Column joinColumn)` Collects all columns in this table and its children.
`String`	`generateSql(List<RolapStar.Column> columnList, List<String> columnNameList)` Generates a SQL statement to read all instances of the given attributes.
`List<AggStar>`	`getAggStars()` Returns this RolapStar's aggregate table AggStars, ordered in ascending order of size.
`List<String>`	`getAliasList()` Returns a list of all aliases used in this star.
`BitKey`	`getBitKey(String[] tableAlias, String[] columnName)`
`Object`	`getCellFromAllCaches(CellRequest request)`
`Object`	`getCellFromCache(CellRequest request, RolapAggregationManager.PinSet pinSet)` Retrieves the value of the cell identified by a cell request, if it can be found in the local cache of the current statement (thread).
`DataSourceChangeListener`	`getChangeListener()` Returns the listener for changes to this star's underlying database.
`RolapStar.Column`	`getColumn(int bitPos)` Look up the column at the given bit position.
`int`	`getColumnCount()` Returns this RolapStar's column count.
`DataSource`	`getDataSource()` Returns the DataSource used to connect to the underlying DBMS.
`RolapStar.Table`	`getFactTable()` Returns the fact table at the center of this RolapStar.
`RolapSchema`	`getSchema()`
`SqlQuery`	`getSqlQuery()` Clones an existing SqlQuery to create a new one (this cloning creates one with an empty sql query).
`Dialect`	`getSqlQueryDialect()` Returns this RolapStar's SQL dialect.
`static RolapStar.Measure`	`getStarMeasure(Member member)` Retrieves the `RolapStar.Measure` in which a measure is stored.
`RolapStatisticsCache`	`getStatisticsCache()`
`MondrianDef.RelationOrJoin`	`getUniqueRelation(MondrianDef.RelationOrJoin rel, String factForeignKey, String primaryKey, String primaryKeyTable)` Generates a unique relational join to the fact table via re-aliasing MondrianDef.Relations currently called in the RolapCubeHierarchy constructor.
`RolapStar.Column`	`lookupColumn(String tableAlias, String columnName)` This is used by TestAggregationManager only.
`RolapStar.Column[]`	`lookupColumns(String tableAlias, String columnName)` Retrieves a named column, returns null if not found.
`Aggregation`	`lookupOrCreateAggregation(AggregationKey aggregationKey)` Looks up an aggregation or creates one if it does not exist in an atomic (synchronized) operation.
`Aggregation`	`lookupSegment(AggregationKey aggregationKey)` Looks for an existing aggregation over a given set of columns, in the local segment cache, returning `null` if there is none.
`void`	`prepareToLoadAggregates()` Place holder in case in the future we wish to be able to reload aggregates.
`void`	`print(PrintWriter pw, String prefix, boolean structure)` Prints the state of this `RolapStar`
`void`	`register(SegmentWithData segment)`
`void`	`reOrderAggStarList()` Reorder the list of aggregate stars.
`void`	`setChangeListener(DataSourceChangeListener changeListener)` Sets the listener for changes to this star's underlying database.
`void`	`setDataSource(DataSource dataSource)` For testing purposes only.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Method Detail
  - getCellFromCache
```
public Object getCellFromCache(CellRequest request,
                               RolapAggregationManager.PinSet pinSet)
```
    Retrieves the value of the cell identified by a cell request, if it can be found in the local cache of the current statement (thread).
    If it is not in the local cache, returns null. The client's next step will presumably be to request a segment that contains the cell from the global cache, external cache, or by issuing a SQL statement.
    Returns Util.nullValue if a segment contains the cell and the cell's value is null.
    If pinSet is not null, pins the segment that holds it into the local cache. pinSet ensures that a segment is only pinned once.
    
    Parameters:
    
    request - Cell request
    
    pinSet - Set into which to pin the segment; or null
    
    Returns:
    
    Cell value, or Util.nullValue if the cell value is null, or null if the cell is not in any segment in the local cache.
  - getCellFromAllCaches
```
public Object getCellFromAllCaches(CellRequest request)
```
  - register
```
public void register(SegmentWithData segment)
```
  - getStatisticsCache
```
public RolapStatisticsCache getStatisticsCache()
```
  - cloneRelation
```
protected MondrianDef.RelationOrJoin cloneRelation(MondrianDef.Relation rel,
                                                   String possibleName)
```
  - getUniqueRelation
```
public MondrianDef.RelationOrJoin getUniqueRelation(MondrianDef.RelationOrJoin rel,
                                                    String factForeignKey,
                                                    String primaryKey,
                                                    String primaryKeyTable)
```
    Generates a unique relational join to the fact table via re-aliasing MondrianDef.Relations currently called in the RolapCubeHierarchy constructor. This should eventually be phased out and replaced with RolapStar.Table and RolapStar.Column references
    
    Parameters:
    
    rel - the relation needing uniqueness
    
    factForeignKey - the foreign key of the fact table
    
    primaryKey - the join key of the relation
    
    primaryKeyTable - the join table of the relation
    
    Returns:
    
    if necessary a new relation that has been re-aliased
  - getColumnCount
```
public int getColumnCount()
```
    Returns this RolapStar's column count. After a star has been created with all of its columns, this is the number of columns in the star.
  - prepareToLoadAggregates
```
public void prepareToLoadAggregates()
```
    Place holder in case in the future we wish to be able to reload aggregates. In that case, if aggregates had already been loaded, i.e., this star has some aggstars, then those aggstars are cleared.
  - addAggStar
```
public void addAggStar(AggStar aggStar)
```
    Adds an AggStar to this star.
    Internally the AggStars are added in sort order, smallest row count to biggest, so that the most efficient AggStar is encountered first; ties do not matter.
  - reOrderAggStarList
```
public void reOrderAggStarList()
```
    Reorder the list of aggregate stars. This should be called if the algorithm used to order the AggStars has been changed.
  - getAggStars
```
public List<AggStar> getAggStars()
```
    Returns this RolapStar's aggregate table AggStars, ordered in ascending order of size.
  - getFactTable
```
public RolapStar.Table getFactTable()
```
    Returns the fact table at the center of this RolapStar.
    
    Returns:
    
    fact table
  - getSqlQuery
```
public SqlQuery getSqlQuery()
```
    Clones an existing SqlQuery to create a new one (this cloning creates one with an empty sql query).
  - getSqlQueryDialect
```
public Dialect getSqlQueryDialect()
```
    Returns this RolapStar's SQL dialect.
  - lookupOrCreateAggregation
```
public Aggregation lookupOrCreateAggregation(AggregationKey aggregationKey)
```
    Looks up an aggregation or creates one if it does not exist in an atomic (synchronized) operation.
    When a new aggregation is created, it is marked as thread local.
    
    Parameters:
    
    aggregationKey - this is the constrained column bitkey
  - lookupSegment
```
public Aggregation lookupSegment(AggregationKey aggregationKey)
```
    Looks for an existing aggregation over a given set of columns, in the local segment cache, returning null if there is none.
    Must be called from synchronized context.
    
    See Also:
    
    currently always returns null -- remove
  - setDataSource
```
public void setDataSource(DataSource dataSource)
```
    For testing purposes only.
  - getDataSource
```
public DataSource getDataSource()
```
    Returns the DataSource used to connect to the underlying DBMS.
    
    Returns:
    
    DataSource
  - getStarMeasure
```
public static RolapStar.Measure getStarMeasure(Member member)
```
    Retrieves the RolapStar.Measure in which a measure is stored.
  - lookupColumns
```
public RolapStar.Column[] lookupColumns(String tableAlias,
                                        String columnName)
```
    Retrieves a named column, returns null if not found.
  - lookupColumn
```
public RolapStar.Column lookupColumn(String tableAlias,
                                     String columnName)
```
    This is used by TestAggregationManager only.
  - getBitKey
```
public BitKey getBitKey(String[] tableAlias,
                        String[] columnName)
```
  - getAliasList
```
public List<String> getAliasList()
```
    Returns a list of all aliases used in this star.
  - collectColumns
```
public static void collectColumns(Collection<RolapStar.Column> columnList,
                                  RolapStar.Table table,
                                  MondrianDef.Column joinColumn)
```
    Collects all columns in this table and its children. If joinColumn is specified, only considers child tables joined by the given column.
  - getColumn
```
public RolapStar.Column getColumn(int bitPos)
```
    Look up the column at the given bit position.
    
    Parameters:
    
    bitPos - bit position to look up
    
    Returns:
    
    column at the given position
  - getSchema
```
public RolapSchema getSchema()
```
  - generateSql
```
public String generateSql(List<RolapStar.Column> columnList,
                          List<String> columnNameList)
```
    Generates a SQL statement to read all instances of the given attributes.
    The SQL statement is of the form SELECT ... FROM ... JOIN ... GROUP BY .... It is useful for populating an aggregate table.
    
    Parameters:
    
    columnList - List of columns (attributes and measures)
    
    columnNameList - List of column names (must have same cardinality as columnList)
    
    Returns:
    
    SQL SELECT statement
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - print
```
public void print(PrintWriter pw,
                  String prefix,
                  boolean structure)
```
    Prints the state of this RolapStar
    
    Parameters:
    
    pw - Writer
    
    prefix - Prefix to print at the start of each line
    
    structure - Whether to print the structure of the star
  - getChangeListener
```
public DataSourceChangeListener getChangeListener()
```
    Returns the listener for changes to this star's underlying database.
    
    Returns:
    
    Returns the Data source change listener.
  - setChangeListener
```
public void setChangeListener(DataSourceChangeListener changeListener)
```
    Sets the listener for changes to this star's underlying database.
    
    Parameters:
    
    changeListener - The Data source change listener to set

Class RolapStar

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

getCellFromCache

getCellFromAllCaches

register

getStatisticsCache

cloneRelation

getUniqueRelation

getColumnCount

prepareToLoadAggregates

addAggStar

reOrderAggStarList

getAggStars

getFactTable

getSqlQuery

getSqlQueryDialect

lookupOrCreateAggregation

lookupSegment

setDataSource

getDataSource

getStarMeasure

lookupColumns

lookupColumn

getBitKey

getAliasList

collectColumns

getColumn

getSchema

generateSql

toString

print

getChangeListener

setChangeListener