org.apache.phoenix.expression

Class RowKeyColumnExpression

java.lang.Object

org.apache.phoenix.expression.BaseExpression

org.apache.phoenix.expression.BaseTerminalExpression

org.apache.phoenix.expression.ColumnExpression

org.apache.phoenix.expression.RowKeyColumnExpression

All Implemented Interfaces:

org.apache.hadoop.io.Writable, Expression, PDatum

public class RowKeyColumnExpression
extends ColumnExpression

Class to access a value stored in the row key

Since:

0.1

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.phoenix.expression.BaseExpression

BaseExpression.ExpressionComparabilityWrapper

Field Summary

Fields

Modifier and Type	Field and Description
protected String	name

Fields inherited from class org.apache.phoenix.expression.ColumnExpression

type

Constructor Summary

Constructors

Constructor and Description
RowKeyColumnExpression()
RowKeyColumnExpression(PDatum datum, RowKeyValueAccessor accessor)
RowKeyColumnExpression(PDatum datum, RowKeyValueAccessor accessor, PDataType fromType)
RowKeyColumnExpression(PDatum datum, RowKeyValueAccessor accessor, String name)

Method Summary

Methods

Modifier and Type	Method and Description
<T> T	accept(ExpressionVisitor<T> visitor) Means of traversing expression tree through visitor.
boolean	equals(Object obj)
boolean	evaluate(Tuple tuple, ImmutableBytesWritable ptr) Access the value by setting a pointer to it (as opposed to making a copy of it which can be expensive)
String	getName()
int	getPosition()
int	hashCode()
void	readFields(DataInput input)
boolean	requiresFinalEvaluation() Since we may never have encountered a key value column of interest, but the expression may evaluate to true just based on the row key columns, we need to do a final evaluation.
void	setOffset(int offset) Used to set an offset to be skipped from the start of a the row key.
String	toString()
void	write(DataOutput output)

Methods inherited from class org.apache.phoenix.expression.ColumnExpression

getDataType, getMaxLength, getScale, getSortOrder, isNullable

Methods inherited from class org.apache.phoenix.expression.BaseTerminalExpression

getChildren

Methods inherited from class org.apache.phoenix.expression.BaseExpression

acceptChildren, coerce, coerce, getDeterminism, isStateless, reset

Methods inherited from class java.lang.Object

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

Field Detail

name

protected final String name

Constructor Detail

RowKeyColumnExpression

public RowKeyColumnExpression()

RowKeyColumnExpression

public RowKeyColumnExpression(PDatum datum,
                      RowKeyValueAccessor accessor)

RowKeyColumnExpression

public RowKeyColumnExpression(PDatum datum,
                      RowKeyValueAccessor accessor,
                      String name)

RowKeyColumnExpression

public RowKeyColumnExpression(PDatum datum,
                      RowKeyValueAccessor accessor,
                      PDataType fromType)

Method Detail

setOffset

public void setOffset(int offset)

Used to set an offset to be skipped from the start of a the row key. Used by local indexing to skip the region start key bytes.

Parameters:

offset - the number of bytes to offset accesses to row key columns

getPosition

public int getPosition()

getName

public String getName()

hashCode

public int hashCode()

Overrides:

hashCode in class ColumnExpression

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class ColumnExpression

evaluate

public boolean evaluate(Tuple tuple,
               ImmutableBytesWritable ptr)

Description copied from interface: Expression

Access the value by setting a pointer to it (as opposed to making a copy of it which can be expensive)

Parameters:

tuple - Single row result during scan iteration

ptr - Pointer to byte value being accessed

Returns:

true if the expression could be evaluated (i.e. ptr was set) and false otherwise

readFields

public void readFields(DataInput input)
                throws IOException

Specified by:

readFields in interface org.apache.hadoop.io.Writable

Overrides:

readFields in class ColumnExpression

Throws:

IOException

write

public void write(DataOutput output)
           throws IOException

Specified by:

write in interface org.apache.hadoop.io.Writable

Overrides:

write in class ColumnExpression

Throws:

IOException

accept

public final <T> T accept(ExpressionVisitor<T> visitor)

Description copied from interface: Expression

Means of traversing expression tree through visitor.

requiresFinalEvaluation

public boolean requiresFinalEvaluation()

Since we may never have encountered a key value column of interest, but the expression may evaluate to true just based on the row key columns, we need to do a final evaluation. An example of when this would be required is: SELECT a FROM t WHERE a = 5 OR b = 2 in the case where a is a PK column, b is a KV column and no b KV is found.

Specified by:

requiresFinalEvaluation in interface Expression

Overrides:

requiresFinalEvaluation in class BaseExpression

Returns: