net.sf.saffron.ext
Class ExtentRel

java.lang.Object
  |
  +--net.sf.saffron.rel.SaffronRel
        |
        +--net.sf.saffron.ext.ExtentRel

public class ExtentRel

extends SaffronRel

ExtentRel represents all of the instances of a particular class (including subtypes).

It cannot be implemented as such, but can often be transformed into an expression which can. For example, in

JavaReflectConnection reflect;
 select
 from reflect.fields as field
 join reflect.classes as clazz
 on field.getDeclaringClass() == clazz &&
     clazz.getPackage().getName().equals("java.lang");

the field and clazz are constrained by join and filter conditions so that we can enumerate the required fields.

todo: Why is this not just a TableAccess?

See Also:

ExtentTable

Field Summary

private SaffronTable

table

Fields inherited from class net.sf.saffron.rel.SaffronRel

cluster, digest, id, rowType

Constructor Summary

ExtentRel(VolcanoCluster cluster, SaffronType rowType, SaffronTable table)
Creates an ExtentRel.

Method Summary

Object	clone()
protected SaffronType	deriveRowType()
void	explain(PlanWriter pw)
SaffronTable	getTable() If this relational expression represents an access to a table, returns that table, otherwise returns null.
boolean	isDistinct() Returns whether the same value will not come out twice.

Methods inherited from class net.sf.saffron.rel.SaffronRel

childrenAccept, computeDigest, computeSelfCost, getChildExps, getCluster, getConvention, getCorrelVariable, getId, getInput, getInputs, getOrCreateCorrelVariable, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getVariablesStopped, implement, implementFieldAccess, isAccessTo, onRegister, recomputeDigest, register, registerCorrelVariable, replaceInput, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

table

private SaffronTable table

Constructor Detail

ExtentRel

public ExtentRel(VolcanoCluster cluster,
                 SaffronType rowType,
                 SaffronTable table)

Creates an ExtentRel.

Pre-condition:

rowType != null, table != null

Method Detail

isDistinct

public boolean isDistinct()

Description copied from class: SaffronRel

Returns whether the same value will not come out twice. Default value is false, derived classes should override.

Overrides:

isDistinct in class SaffronRel

clone

public Object clone()

Specified by:

clone in class SaffronRel

explain

public void explain(PlanWriter pw)

Overrides:

explain in class SaffronRel

getTable

public SaffronTable getTable()

Description copied from class: SaffronRel

If this relational expression represents an access to a table, returns that table, otherwise returns null.

Overrides:

getTable in class SaffronRel

deriveRowType

protected SaffronType deriveRowType()

Specified by:

deriveRowType in class SaffronRel