org.apache.derby.impl.store.access.heap

Class HeapRowLocation

java.lang.Object

org.apache.derby.iapi.types.DataType

org.apache.derby.impl.store.access.heap.HeapRowLocation

All Implemented Interfaces:

java.io.Externalizable, java.io.Serializable, java.lang.Comparable, Formatable, Storable, TypedFormat, DataValueDescriptor, Orderable, RowLocation

public class HeapRowLocation
extends DataType
implements RowLocation

A heap row location represents the location of a row in the heap.

It is implementad as a wrapper around a raw store record handle.

See Also:

Serialized Form

Format ID	ACCESS_HEAP_ROW_LOCATION_V1_ID
Purpose	Object used to store the location of a row within a Heap table. One of these is stored in every row of a btree secondary index built on a heap base table.
Upgrade	The type of the btree determines the type of rowlocation stored. In current btree implementations only one type of rowlocation can be stored per tree, and it's type is stored in the format id array stored in the Conglomerate object.
Disk Layout	page number(CompressedNumber.writeLong()) record id(CompressedNumber.writeInt())

Field Summary

Fields

Modifier and Type	Field and Description
private static int	BASE_MEMORY_USAGE
private long	pageno The HeapRowLocation simply maintains a raw store record handle.
private int	recid
private static int	RECORD_HANDLE_MEMORY_USAGE
private RecordHandle	rh

Fields inherited from interface org.apache.derby.iapi.types.DataValueDescriptor

UNKNOWN_LOGICAL_LENGTH

Fields inherited from interface org.apache.derby.iapi.types.Orderable

ORDER_OP_EQUALS, ORDER_OP_GREATEROREQUALS, ORDER_OP_GREATERTHAN, ORDER_OP_LESSOREQUALS, ORDER_OP_LESSTHAN

Constructor Summary

Constructors

Modifier	Constructor and Description
	HeapRowLocation()
private	HeapRowLocation(HeapRowLocation other)
(package private)	HeapRowLocation(RecordHandle rh)

Method Summary

Methods

Modifier and Type	Method and Description
DataValueDescriptor	cloneValue(boolean forceMaterialization) Clone this DataValueDescriptor.
int	compare(DataValueDescriptor other) Compare this Orderable with a given Orderable for the purpose of index positioning.
boolean	compare(int op, DataValueDescriptor other, boolean orderedNulls, boolean unknownRV) Compare this Orderable with a given Orderable for the purpose of qualification and sorting.
boolean	equals(java.lang.Object ref) Implement value equality.
int	estimateMemoryUsage() Estimate the memory usage in bytes of the data value and the overhead of the class.
int	getLength() Gets the length of the data value.
DataValueDescriptor	getNewNull() Get a new null value of the same type as this data value.
java.lang.Object	getObject() Gets the value in the data value descriptor as a int.
RecordHandle	getRecordHandle(ContainerHandle ch)
java.lang.String	getString() Gets the value in the data value descriptor as a String.
int	getTypeFormatId() Return my format identifier.
java.lang.String	getTypeName() Get the SQL name of the datatype
int	hashCode() Return a hashcode based on value.
boolean	isNull() Return whether the value is null or not.
void	readExternal(java.io.ObjectInput in)
void	readExternalFromArray(ArrayInputStream in) Read the DataValueDescriptor from the stream.
DataValueDescriptor	recycle() Recycle this HeapRowLocation object.
void	restoreToNull() Restore this object to its (SQL)null value.
protected void	setFrom(DataValueDescriptor theValue) Set the value of this DataValueDescriptor based on the value of the specified DataValueDescriptor.
(package private) void	setFrom(RecordHandle rh)
void	setValueFromResultSet(java.sql.ResultSet resultSet, int colNumber, boolean isNullable) Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.
java.lang.String	toString()
void	writeExternal(java.io.ObjectOutput out)

Methods inherited from class org.apache.derby.iapi.types.DataType

checkHostVariable, cloneHolder, coalesce, compare, compare, compareTo, dataTypeConversion, equals, flip, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getShort, getStream, getTime, getTimestamp, getTraceString, greaterOrEquals, greaterThan, hasStream, in, invalidFormat, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, outOfRange, setBigDecimal, setInto, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, throwLangSetMismatch, typePrecedence, typeToBigDecimal

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.derby.iapi.types.DataValueDescriptor

checkHostVariable, cloneHolder, coalesce, compare, compare, equals, getBoolean, getByte, getBytes, getDate, getDouble, getFloat, getInt, getLong, getShort, getStream, getTime, getTimestamp, getTraceString, greaterOrEquals, greaterThan, hasStream, in, isNotNull, isNullOp, lessOrEquals, lessThan, normalize, notEquals, setBigDecimal, setInto, setInto, setObjectForCast, setToNull, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, setValue, typePrecedence, typeToBigDecimal

Field Detail

pageno

private long pageno

The HeapRowLocation simply maintains a raw store record handle.

recid

private int recid

rh

private RecordHandle rh

BASE_MEMORY_USAGE

private static final int BASE_MEMORY_USAGE

RECORD_HANDLE_MEMORY_USAGE

private static final int RECORD_HANDLE_MEMORY_USAGE

Constructor Detail

HeapRowLocation

HeapRowLocation(RecordHandle rh)

HeapRowLocation

public HeapRowLocation()

HeapRowLocation

private HeapRowLocation(HeapRowLocation other)

Method Detail

estimateMemoryUsage

public int estimateMemoryUsage()

Description copied from interface: DataValueDescriptor

Estimate the memory usage in bytes of the data value and the overhead of the class.

Specified by:

estimateMemoryUsage in interface DataValueDescriptor

Returns:

the estimated memory usage

getTypeName

public java.lang.String getTypeName()

Description copied from interface: DataValueDescriptor

Get the SQL name of the datatype

Specified by:

getTypeName in interface DataValueDescriptor

Returns:

The SQL name of the datatype

setValueFromResultSet

public void setValueFromResultSet(java.sql.ResultSet resultSet,
                         int colNumber,
                         boolean isNullable)

Description copied from interface: DataValueDescriptor

Set the value based on the value for the specified DataValueDescriptor from the specified ResultSet.

Specified by:

setValueFromResultSet in interface DataValueDescriptor

Parameters:

resultSet - The specified ResultSet.

colNumber - The 1-based column # into the resultSet.

isNullable - Whether or not the column is nullable (No need to call wasNull() if not)

getNewNull

public DataValueDescriptor getNewNull()

Description copied from interface: DataValueDescriptor

Get a new null value of the same type as this data value.

Specified by:

getNewNull in interface DataValueDescriptor

getObject

public java.lang.Object getObject()

Description copied from class: DataType

Gets the value in the data value descriptor as a int. Throws an exception if the data value is not receivable as a int.

Specified by:

getObject in interface DataValueDescriptor

Overrides:

getObject in class DataType

Returns:

The data value as a int.

cloneValue

public DataValueDescriptor cloneValue(boolean forceMaterialization)

Description copied from interface: DataValueDescriptor

Clone this DataValueDescriptor. Results in a new object that has the same value as this but can be modified independently.

Even though the objects can be modified independently regardless of the value of forceMaterialization, both the clone and the original may be dependent on the store state if forceMaterialization is set to false. An example is if you need to access the value you just read using cloneValue after the current transaction has ended, or after the source result set has been closed.

Specified by:

cloneValue in interface DataValueDescriptor

Parameters:

forceMaterialization - any streams representing the data value will be materialized if true, the data value will be kept as a stream if possible if false

Returns:

A clone of the DataValueDescriptor with the same initial value as this.

recycle

public DataValueDescriptor recycle()

Recycle this HeapRowLocation object.

Specified by:

recycle in interface DataValueDescriptor

Overrides:

recycle in class DataType

Returns:

this object reset to its initial state

getLength

public int getLength()

Description copied from interface: DataValueDescriptor

Gets the length of the data value. The meaning of this is implementation-dependent. For string types, it is the number of characters in the string. For numeric types, it is the number of bytes used to store the number. This is the actual length of this value, not the length of the type it was defined as. For example, a VARCHAR value may be shorter than the declared VARCHAR (maximum) length.

Specified by:

getLength in interface DataValueDescriptor

Returns:

The length of the data value

getString

public java.lang.String getString()

Description copied from interface: DataValueDescriptor

Gets the value in the data value descriptor as a String. Throws an exception if the data value is not a string.

Specified by:

getString in interface DataValueDescriptor

Returns:

The data value as a String.

compare

public boolean compare(int op,
              DataValueDescriptor other,
              boolean orderedNulls,
              boolean unknownRV)

Description copied from interface: DataValueDescriptor

Compare this Orderable with a given Orderable for the purpose of qualification and sorting. The caller gets to determine how nulls should be treated - they can either be ordered values or unknown values.

Specified by:

compare in interface DataValueDescriptor

Overrides:

compare in class DataType

Parameters:

op - Orderable.ORDER_OP_EQUALS means do an = comparison. Orderable.ORDER_OP_LESSTHAN means compare this < other. Orderable.ORDER_OP_LESSOREQUALS means compare this <= other.

other - The DataValueDescriptor to compare this one to.

orderedNulls - True means to treat nulls as ordered values, that is, treat SQL null as equal to null, and less than all other values. False means to treat nulls as unknown values, that is, the result of any comparison with a null is the UNKNOWN truth value.

unknownRV - The return value to use if the result of the comparison is the UNKNOWN truth value. In other words, if orderedNulls is false, and a null is involved in the comparison, return unknownRV. This parameter is not used orderedNulls is true.

Returns:

true if the comparison is true (duh!)

compare

public int compare(DataValueDescriptor other)

Description copied from interface: DataValueDescriptor

Compare this Orderable with a given Orderable for the purpose of index positioning. This method treats nulls as ordered values - that is, it treats SQL null as equal to null and greater than all other values.

Specified by:

compare in interface DataValueDescriptor

Parameters:

other - The Orderable to compare this one to.

Returns:

<0 - this Orderable is less than other. 0 - this Orderable equals other. >0 - this Orderable is greater than other. The code should not explicitly look for -1, or 1.

getRecordHandle

public RecordHandle getRecordHandle(ContainerHandle ch)
                             throws StandardException

Throws:

StandardException

setFrom

void setFrom(RecordHandle rh)

getTypeFormatId

public int getTypeFormatId()

Return my format identifier.

Specified by:

getTypeFormatId in interface TypedFormat

Returns:

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

See Also:

TypedFormat.getTypeFormatId()

isNull

public boolean isNull()

Description copied from interface: Storable

Return whether the value is null or not.

Specified by:

isNull in interface Storable

Returns:

true if the value is null and false otherwise.

writeExternal

public void writeExternal(java.io.ObjectOutput out)
                   throws java.io.IOException

Specified by:

writeExternal in interface java.io.Externalizable

Throws:

java.io.IOException

readExternal

public void readExternal(java.io.ObjectInput in)
                  throws java.io.IOException,
                         java.lang.ClassNotFoundException

Specified by:

readExternal in interface java.io.Externalizable

Throws:

java.lang.ClassNotFoundException - A class needed to read the stored form of this object could not be found.

java.io.IOException

See Also:

Externalizable.readExternal(java.io.ObjectInput)

readExternalFromArray

public void readExternalFromArray(ArrayInputStream in)
                           throws java.io.IOException,
                                  java.lang.ClassNotFoundException

Description copied from class: DataType

Read the DataValueDescriptor from the stream. The default implementation calls readExternal(), which accesses the ArrayInputStream as a generic stream. If sub-classes can implement it more efficiently by accessing the array, they should override this method.

Specified by:

readExternalFromArray in interface DataValueDescriptor

Overrides:

readExternalFromArray in class DataType

Parameters:

in - The array stream positioned at the beginning of the byte stream to read from.

Throws:

java.io.IOException - Usual error is if you try to read past limit on the stream.

java.lang.ClassNotFoundException - If a necessary class can not be found while reading the object from the stream.

See Also:

DataValueDescriptor.readExternalFromArray(org.apache.derby.iapi.services.io.ArrayInputStream), Externalizable.readExternal(java.io.ObjectInput)

restoreToNull

public void restoreToNull()

Description copied from interface: Storable

Restore this object to its (SQL)null value.

Specified by:

restoreToNull in interface Storable

setFrom

protected void setFrom(DataValueDescriptor theValue)

Description copied from class: DataType

Set the value of this DataValueDescriptor based on the value of the specified DataValueDescriptor.

Overrides:

setFrom in class DataType

Parameters:

theValue - The DataValueDescriptor that holds the value to which we want to set this DataValueDescriptor's value.

equals

public boolean equals(java.lang.Object ref)

Implement value equality.
MT - Thread safe

Overrides:

equals in class DataType

hashCode

public int hashCode()

Return a hashcode based on value.
MT - thread safe

Overrides:

hashCode in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object