Is there any guidelines to choose Map vs. Large Map?


#1

When do I use Map versus a large Map? What are the difference usages?


#2

Post by peter » Fri Jun 27, 2014 11:14 am

A Map is best to store a smaller number of elements that are all used at the same time. Like a Java HashTable or anything that implements the Map interface.

  • When a Map is requested from the Client, the whole Map is returned to the Client and placed in a language specific Map.
  • A Map is stored “in-line” in a record, therefore the number of elements in a Map is limited by how many can fit into the size of a record.

A Large Map has no limit to the number of elements, therefore it is good for storing thousands to millions of elements, each element is a “sub record”.

  • A Client can request 1 or all elements from a Large Map, the client controls the size of the request.
  • Retrieving elements from a Large Map can also be filtered (predicate filter) similar to a “where” clause.
  • A Large Map is like a sub Key-Value store