CRUD
Tuesday, February 23, 2010
7:57 PM
CRUD and MapReduce
MapReduce can implement distributed CRUD
Create a <key,value> pair.
Retrieve a <key, value> pair. 
Update a value for a key. 
Delete a <key,value> pair. 
Create
Map: choose one (or more) elements to store <key, value>
Reduce: count number of created pairs. 
Retrieve
Map: return value for key, nothing if no match. 
Reduce: ignore empty returns. 
Update:
Map: put new value everywhere old value lives. 
Reduce: count changes made. 
Delete: 
Map: delete all instances of given key. 
Reduce: count deletions done. 