mondrian.spi

Class SegmentHeader

java.lang.Object

mondrian.spi.SegmentHeader

All Implemented Interfaces:

Serializable

public class SegmentHeader
extends Object
implements Serializable

SegmentHeaders are the key objects used to retrieve the segments from the segment cache.

The segment header objects are immutable and fully serializable.

The headers have each an ID which is a SHA-256 checksum of the following properties, concatenated. See getUniqueID()

• Schema Name
• Cube Name
• Measure Name
• For each column:
• Column table name
• Column physical name
• For each predicate value:
• The equivalent of String.valueof([value object])

Author:

LBoudreau

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
List<String>	compoundPredicates
BitKey	constrainedColsBitKey
String	cubeName
String	measureName
String	rolapStarFactTableName
ByteString	schemaChecksum
String	schemaName

Constructor Summary

Constructors

Constructor and Description
SegmentHeader(String schemaName, ByteString schemaChecksum, String cubeName, String measureName, List<SegmentColumn> constrainedColumns, List<String> compoundPredicates, String rolapStarFactTableName, BitKey constrainedColsBitKey, List<SegmentColumn> excludedRegions) Creates a segment header.

Method Summary

Modifier and Type	Method and Description
boolean	canConstrain(SegmentColumn[] region) Checks if this header can be constrained by a given region.
SegmentHeader	clone(SegmentColumn[] overrideValues) Creates a clone of this header by replacing some of the constrained columns in the process.
SegmentHeader	constrain(SegmentColumn[] region) Applies a set of exclusions to this segment header and returns a new segment header representing the original one to which a region has been excluded.
boolean	equals(Object obj)
int	getArity() Returns the arity of this SegmentHeader.
SegmentColumn	getConstrainedColumn(String columnExpression) Returns the constrained column object, if any, corresponding to a column name and a table name.
List<SegmentColumn>	getConstrainedColumns() Returns a list of constrained columns which define this segment header.
BitKey	getConstrainedColumnsBitKey()
String	getDescription() Returns a human readable description of this segment header.
SegmentColumn	getExcludedRegion(String columnExpression)
List<SegmentColumn>	getExcludedRegions()
ByteString	getUniqueID() Returns a unique identifier for this header.
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

compoundPredicates

public final List<String> compoundPredicates

measureName

public final String measureName

cubeName

public final String cubeName

schemaName

public final String schemaName

rolapStarFactTableName

public final String rolapStarFactTableName

constrainedColsBitKey

public final BitKey constrainedColsBitKey

schemaChecksum

public final ByteString schemaChecksum

Constructor Detail

SegmentHeader

public SegmentHeader(String schemaName,
                     ByteString schemaChecksum,
                     String cubeName,
                     String measureName,
                     List<SegmentColumn> constrainedColumns,
                     List<String> compoundPredicates,
                     String rolapStarFactTableName,
                     BitKey constrainedColsBitKey,
                     List<SegmentColumn> excludedRegions)

Creates a segment header.

Parameters:

schemaName - The name of the schema which this header belongs to.

schemaChecksum - Schema checksum

cubeName - The name of the cube this segment belongs to.

measureName - The name of the measure which defines this header.

constrainedColumns - An array of constrained columns objects which define the predicated of this segment header.

compoundPredicates - Compound predicates (Must not be null, but typically empty.)

rolapStarFactTableName - Star fact table name

constrainedColsBitKey - Constrained columns bit key

excludedRegions - Excluded regions. (Must not be null, but typically

Method Detail

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

clone

public SegmentHeader clone(SegmentColumn[] overrideValues)

Creates a clone of this header by replacing some of the constrained columns in the process.

Parameters:

overrideValues - A list of constrained columns to either replace or add to the original header.

Returns:

A clone of the header with the columns replaced.

canConstrain

public boolean canConstrain(SegmentColumn[] region)

Checks if this header can be constrained by a given region.

It will return false if the region covers one of the axis in its entirety.

It will return false if the region sits outside of the bounds of this header. This means that when performing a flush operation, the header must be scrapped altogether.

constrain

public SegmentHeader constrain(SegmentColumn[] region)

Applies a set of exclusions to this segment header and returns a new segment header representing the original one to which a region has been excluded.

Parameters:

region - Region

Returns:

Header with constraint applied

toString

public String toString()

Overrides:

toString in class Object

getArity

public int getArity()

Returns the arity of this SegmentHeader.

Returns:

The arity as an integer number.

getExcludedRegions

public List<SegmentColumn> getExcludedRegions()

getConstrainedColumns

public List<SegmentColumn> getConstrainedColumns()

Returns a list of constrained columns which define this segment header. The caller should consider this list immutable.

Returns:

List of ConstrainedColumns

getConstrainedColumn

public SegmentColumn getConstrainedColumn(String columnExpression)

Returns the constrained column object, if any, corresponding to a column name and a table name.

Parameters:

columnExpression - The column name we want.

Returns:

A Constrained column, or null.

getExcludedRegion

public SegmentColumn getExcludedRegion(String columnExpression)

getConstrainedColumnsBitKey

public BitKey getConstrainedColumnsBitKey()

getUniqueID

public ByteString getUniqueID()

Returns a unique identifier for this header. The identifier can be used for storage and will be the same across segments which have the same schema name, cube name, measure name, and for each constrained column, the same column name, table name, and predicate values.

Returns:

A unique identification string.

getDescription

public String getDescription()

Returns a human readable description of this segment header.

Returns:

A string describing the header.