Class IndexDescriptorImpl

java.lang.Object

org.apache.derby.catalog.types.IndexDescriptorImpl

All Implemented Interfaces:

Externalizable, Serializable, IndexDescriptor, Formatable, TypedFormat

public class IndexDescriptorImpl
extends Object
implements IndexDescriptor, Formatable

See also IndexRowGenerator.

For a description of how deferrable and non-deferrable constraints are backed differently, including the meaning of the boolean attributes used here, see IndexDescriptor.

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private int[]	baseColumnPositions
private boolean	hasDeferrableChecking	The index represents a constraint which is deferrable.
private String	indexType
private boolean[]	isAscending
private boolean	isUnique	This class implements Formatable.
private boolean	isUniqueDeferrable	The index represents a PRIMARY KEY or a UNIQUE NOT NULL constraint which is deferrable.
private boolean	isUniqueWithDuplicateNulls
private int	numberOfOrderedColumns

Constructor Summary

Constructors

Constructor	Description
IndexDescriptorImpl()	Zero-argument constructor for Formatable interface
IndexDescriptorImpl(String indexType, boolean isUnique, boolean isUniqueWithDuplicateNulls, boolean isUniqueDeferrable, boolean hasDeferrableChecking, int[] baseColumnPositions, boolean[] isAscending, int numberOfOrderedColumns)	Constructor for an IndexDescriptorImpl

Method Summary

Modifier and Type	Method	Description
int[]	baseColumnPositions()	Returns an array of column positions in the base table.
boolean	equals(Object other)	Test for value equality
int	getKeyColumnPosition(int heapColumnPosition)	Returns the postion of a column.
int	getTypeFormatId()	Get a universally unique identifier for the type of this object.
boolean	hasDeferrableChecking()	Returns true if the index is used to support a deferrable constraint.
int	hashCode()
String	indexType()	Returns the type of the index.
boolean[]	isAscending()	Returns array of boolean telling asc/desc info for each index key column for convenience of using together with baseColumnPositions method.
boolean	isAscending(Integer keyColumnPosition)	Returns true if the specified column is ascending in the index (1-based).
boolean	isDescending(Integer keyColumnPosition)	Returns true if the specified column is descending in the index (1-based).
boolean	isUnique()	Returns true if the index is unique.
boolean	isUniqueDeferrable()	The index represents a PRIMARY KEY or a UNIQUE NOT NULL constraint which is deferrable.
boolean	isUniqueWithDuplicateNulls()	Returns true if the index is duplicate keys only for null key parts.
int	numberOfOrderedColumns()	Returns the number of ordered columns.
void	readExternal(ObjectInput in)
void	setBaseColumnPositions(int[] baseColumnPositions)	set the baseColumnPositions field of the index descriptor.
void	setIsAscending(boolean[] isAscending)	set the isAscending field of the index descriptor.
void	setNumberOfOrderedColumns(int numberOfOrderedColumns)	set the numberOfOrderedColumns field of the index descriptor.
String	toString()
void	writeExternal(ObjectOutput out)

Methods inherited from class Object

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

Field Details

isUnique

private boolean isUnique

This class implements Formatable. That means that it can write itself to and from a formatted stream. If you add more fields to this class, make sure that you also write/read them with the writeExternal()/readExternal() methods. If, in between releases, you add more fields to this class, then you should bump the version number emitted by the getTypeFormatId() method.

baseColumnPositions

private int[] baseColumnPositions

isAscending

private boolean[] isAscending

numberOfOrderedColumns

private int numberOfOrderedColumns

indexType

private String indexType

isUniqueWithDuplicateNulls

private boolean isUniqueWithDuplicateNulls

isUniqueDeferrable

private boolean isUniqueDeferrable

The index represents a PRIMARY KEY or a UNIQUE NOT NULL constraint which is deferrable. true implies isUnique == false and isUniqueWithDuplicateNulls == false and hasDeferrableChecking == true.

hasDeferrableChecking

private boolean hasDeferrableChecking

The index represents a constraint which is deferrable.

Constructor Details

IndexDescriptorImpl

public IndexDescriptorImpl(String indexType,
 boolean isUnique,
 boolean isUniqueWithDuplicateNulls,
 boolean isUniqueDeferrable,
 boolean hasDeferrableChecking,
 int[] baseColumnPositions,
 boolean[] isAscending,
 int numberOfOrderedColumns)

Constructor for an IndexDescriptorImpl

Parameters:

indexType - The type of index

isUnique - True means the index is unique

isUniqueWithDuplicateNulls - True means the index will be unique for non null values but duplicate nulls will be allowed. This parameter has no effect if the isUnique is true. If isUnique is false and isUniqueWithDuplicateNulls is set to true the index will allow duplicate nulls but for non null keys will act like a unique index.

isUniqueDeferrable - True means the index represents a PRIMARY KEY or a UNIQUE NOT NULL constraint which is deferrable.

hasDeferrableChecking - True if this index supports a deferrable constraint.

baseColumnPositions - An array of column positions in the base table. Each index column corresponds to a column position in the base table.

isAscending - An array of booleans telling asc/desc on each column.

numberOfOrderedColumns - In the future, it will be possible to store non-ordered columns in an index. These will be useful for covered queries.

IndexDescriptorImpl

public IndexDescriptorImpl()

Zero-argument constructor for Formatable interface

Method Details

isUniqueWithDuplicateNulls

public boolean isUniqueWithDuplicateNulls()

Description copied from interface: IndexDescriptor

Returns true if the index is duplicate keys only for null key parts. This is effective only if isUnique is false.

Specified by:

isUniqueWithDuplicateNulls in interface IndexDescriptor

See Also:

• IndexDescriptor.isUniqueWithDuplicateNulls()

hasDeferrableChecking

public boolean hasDeferrableChecking()

Description copied from interface: IndexDescriptor

Returns true if the index is used to support a deferrable constraint.

Specified by:

hasDeferrableChecking in interface IndexDescriptor

Returns:

true is the index supports a deferrable constraint

isUniqueDeferrable

public boolean isUniqueDeferrable()

The index represents a PRIMARY KEY or a UNIQUE NOT NULL constraint which is deferrable. true implies #isUnique() == false and #isUniqueWithDuplicateNulls() == false and #hasDeferrableChecking() == true.

Specified by:

isUniqueDeferrable in interface IndexDescriptor

Returns:

true is the index supports such a constraint

isUnique

public boolean isUnique()

Description copied from interface: IndexDescriptor

Returns true if the index is unique.

Specified by:

isUnique in interface IndexDescriptor

See Also:

• IndexDescriptor.isUnique()

baseColumnPositions

public int[] baseColumnPositions()

Description copied from interface: IndexDescriptor

Returns an array of column positions in the base table. Each index column corresponds to a column position in the base table, except the column representing the location of the row in the base table. The returned array holds the column positions in the base table, so, if entry 2 is the number 4, the second column in the index is the fourth column in the table.

Specified by:

baseColumnPositions in interface IndexDescriptor

See Also:

• IndexDescriptor.baseColumnPositions()

getKeyColumnPosition

public int getKeyColumnPosition(int heapColumnPosition)

Description copied from interface: IndexDescriptor

Returns the postion of a column.

Returns the position of a column within the key (1-based). 0 means that the column is not in the key. Same as the above method, but it uses int instead of Integer.

Specified by:

getKeyColumnPosition in interface IndexDescriptor

See Also:

• IndexDescriptor.getKeyColumnPosition(int)

numberOfOrderedColumns

public int numberOfOrderedColumns()

Description copied from interface: IndexDescriptor

Returns the number of ordered columns.

In the future, it will be possible to store non-ordered columns in an index. These will be useful for covered queries. The ordered columns will be at the beginning of the index row, and they will be followed by the non-ordered columns. For now, all columns in an index must be ordered.

Specified by:

numberOfOrderedColumns in interface IndexDescriptor

See Also:

• IndexDescriptor.numberOfOrderedColumns()

indexType

public String indexType()

Description copied from interface: IndexDescriptor

Returns the type of the index. For now, we only support B-Trees, so the value "BTREE" is returned.

Specified by:

indexType in interface IndexDescriptor

See Also:

• IndexDescriptor.indexType()

isAscending

public boolean isAscending(Integer keyColumnPosition)

Description copied from interface: IndexDescriptor

Returns true if the specified column is ascending in the index (1-based).

Specified by:

isAscending in interface IndexDescriptor

See Also:

• IndexDescriptor.isAscending()

isDescending

public boolean isDescending(Integer keyColumnPosition)

Description copied from interface: IndexDescriptor

Returns true if the specified column is descending in the index (1-based). In the current release, only ascending columns are supported.

Specified by:

isDescending in interface IndexDescriptor

See Also:

• IndexDescriptor.isDescending(Integer)

isAscending

public boolean[] isAscending()

Description copied from interface: IndexDescriptor

Returns array of boolean telling asc/desc info for each index key column for convenience of using together with baseColumnPositions method. Both methods return an array with subscript starting from 0.

Specified by:

isAscending in interface IndexDescriptor

See Also:

• IndexDescriptor.isAscending()

setBaseColumnPositions

public void setBaseColumnPositions(int[] baseColumnPositions)

Description copied from interface: IndexDescriptor

set the baseColumnPositions field of the index descriptor. This is for updating the field in operations such as "alter table drop column" where baseColumnPositions is changed.

Specified by:

setBaseColumnPositions in interface IndexDescriptor

See Also:

• IndexDescriptor.setBaseColumnPositions(int[])

setIsAscending

public void setIsAscending(boolean[] isAscending)

Description copied from interface: IndexDescriptor

set the isAscending field of the index descriptor. This is for updating the field in operations such as "alter table drop column" where isAscending is changed.

Specified by:

setIsAscending in interface IndexDescriptor

See Also:

• IndexDescriptor.setIsAscending(boolean[])

setNumberOfOrderedColumns

public void setNumberOfOrderedColumns(int numberOfOrderedColumns)

Description copied from interface: IndexDescriptor

set the numberOfOrderedColumns field of the index descriptor. This is for updating the field in operations such as "alter table drop column" where numberOfOrderedColumns is changed.

Specified by:

setNumberOfOrderedColumns in interface IndexDescriptor

See Also:

• IndexDescriptor.setNumberOfOrderedColumns(int)

toString

public String toString()

Overrides:

toString in class Object

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException - Thrown on read error

ClassNotFoundException

See Also:

• Externalizable.readExternal(ObjectInput)

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException - Thrown on write error

See Also:

• Externalizable.writeExternal(ObjectOutput)

getTypeFormatId

public int getTypeFormatId()

Description copied from interface: TypedFormat

Get a universally unique identifier for the type of this object.

Specified by:

getTypeFormatId in interface TypedFormat

Returns:

The identifier. (A UUID stuffed in an array of 16 bytes).

equals

public boolean equals(Object other)

Test for value equality

Overrides:

equals in class Object

Parameters:

other - The other indexrowgenerator to compare this one with

Returns:

true if this indexrowgenerator has the same value as other

hashCode

public int hashCode()

Overrides:

hashCode in class Object

See Also:

• Object.hashCode()