algebraTree
Class DataUpdate

java.lang.Object
  |
  +--algebraTree.Update
        |
        +--algebraTree.DataUpdate

public class DataUpdate
extends Update

A data update. This is logical only - the physical update should not have anything to do with this class!


Field Summary
protected  Table after
          if "before" is null, we have an add, if "after" is null, we have a delete, otherwise, we have an update.
protected  Table before
          if "before" is null, we have an add, if "after" is null, we have a delete, otherwise, we have an update.
 
Fields inherited from class algebraTree.Update
relation
 
Constructor Summary
DataUpdate(DataUpdate old)
          copy constructor for update propagation
DataUpdate(java.lang.String relationP, Table beforeP, Table afterP)
           
 
Method Summary
 java.lang.String toString()
           
 
Methods inherited from class java.lang.Object
, clone, equals, finalize, getClass, hashCode, notify, notifyAll, registerNatives, wait, wait, wait
 

Field Detail

before

protected Table before
if "before" is null, we have an add, if "after" is null, we have a delete, otherwise, we have an update. Both "before" and "after" must be Tables with exactly one Tuple each. As we can not tell if a key is updated or not, we have no choice but to treat an "update" as an add following a delete; but for the incremental update policy that should not matter

after

protected Table after
if "before" is null, we have an add, if "after" is null, we have a delete, otherwise, we have an update. Both "before" and "after" must be Tables with exactly one Tuple each. As we can not tell if a key is updated or not, we have no choice but to treat an "update" as an add following a delete; but for the incremental update policy that should not matter
Constructor Detail

DataUpdate

public DataUpdate(java.lang.String relationP,
                  Table beforeP,
                  Table afterP)

DataUpdate

public DataUpdate(DataUpdate old)
copy constructor for update propagation
Method Detail

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object