Class ExecRowBuilder

java.lang.Object

org.apache.derby.iapi.sql.execute.ExecRowBuilder

All Implemented Interfaces:

Externalizable, Serializable, Formatable, TypedFormat

public class ExecRowBuilder
extends Object
implements Formatable

A class used for storing information on how to build ExecRow instances. Typically created by the compiler and used during execution to produce and reset row templates.

This class must be Formatable so that it can be stored in the database as part of a stored prepared statement generated for trigger actions or metadata queries. The stored format does not need to be stable across different versions, since the stored prepared statements are discarded on upgrade and will never be read by other Derby versions than the one that originally wrote them.

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
private int[]	columns	Array of 1-based column numbers for the columns to access.
private int	count	The number of columns to set in the row.
private boolean	indexable	If true, the row should be an ExecIndexRow.
private int	maxColumnNumber	The highest column number in the row.
private Object[]	template	Array of templates used for creating NULL values to put in the row.

Constructor Summary

Constructors

Constructor	Description
ExecRowBuilder()	Public no-arg constructor required by the Formatable interface.
ExecRowBuilder(int size, boolean indexable)	Create an instance that produces an ExecRow instance of the specified size.

Method Summary

Modifier and Type	Method	Description
ExecRow	build(ExecutionFactory ef)	Build a new ExecRow instance with the columns specified by the setColumn(int, Object) method initialized to empty (NULL) values.
int	getTypeFormatId()	Get a universally unique identifier for the type of this object.
void	readExternal(ObjectInput in)
void	reset(ExecRow row)	Reset a row by creating fresh NULL values.
void	setColumn(int column, Object columnTemplate)	Add a template from which a NULL value of the correct type can be created.
void	writeExternal(ObjectOutput out)

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

indexable

private boolean indexable

If true, the row should be an ExecIndexRow.

template

private Object[] template

Array of templates used for creating NULL values to put in the row. The templates are either DataValueDescriptors or DataTypeDescriptors.

columns

private int[] columns

Array of 1-based column numbers for the columns to access.

count

private int count

The number of columns to set in the row.

maxColumnNumber

private int maxColumnNumber

The highest column number in the row.

Constructor Details

ExecRowBuilder

public ExecRowBuilder(int size,
 boolean indexable)

Create an instance that produces an ExecRow instance of the specified size.

Parameters:

size - the number of columns to initialize in the produced row

indexable - true if the returned row should be an ExecIndexRow, false otherwise

ExecRowBuilder

public ExecRowBuilder()

Public no-arg constructor required by the Formatable interface. Should not be called directly.

Method Details

setColumn

public void setColumn(int column,
 Object columnTemplate)

Add a template from which a NULL value of the correct type can be created. It should either be a DataValueDescriptor or a DataTypeDescriptor.

Parameters:

column - the column number

columnTemplate - a template from which a NULL value can be created (either a DataValueDescriptor or a DataTypeDescriptor)

build

public ExecRow build(ExecutionFactory ef)
              throws StandardException

Build a new ExecRow instance with the columns specified by the setColumn(int, Object) method initialized to empty (NULL) values.

Parameters:

ef - an execution factory used to create a row

Returns:

a row initialized with NULL values of the requested types

Throws:

StandardException

reset

public void reset(ExecRow row)
           throws StandardException

Reset a row by creating fresh NULL values.

Parameters:

row - the row to reset

Throws:

StandardException

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Specified by:

writeExternal in interface Externalizable

Throws:

IOException

readExternal

public void readExternal(ObjectInput in)
                  throws IOException,
ClassNotFoundException

Specified by:

readExternal in interface Externalizable

Throws:

IOException

ClassNotFoundException

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).