java - Google App Engine Objectify Data Store - entities and queries for recent private user data? -

what efficient way of storing private user-specific data, such documents , images, using objectify in data store?

i'm using google's userfactory logged in user.

by default, user needs see recent entries (say 30 entries), presented on first page. can see older entries moving through pages. number of entries theoretically unbounded.

this seems common scenario, i'm bit confused what's best way go solving in terms of designing entities, can minimise data store operations.

so, here entities came initially:

subclasseduser (extends user, stored entity)  userdocuments - @parent subclasseduser author  - string messagetext - @index datetime updateddate - datetime createdddate  userimages - @parent subclasseduser uploader  - string imageurl - @index datetime createddate 

but here questions:

• is subclassing user appropriate way of storing user?
• the index sorting, can recent entries. idea descending order on date limit display each page. there more efficient way of doing can avoid performing index query, given of time user wants see recent data?
• would there performance issue query if number of userdocuments , userimages continue increase? what's best way of mangaging this?

thank in advance!

you have have index if want retrieve "most recent" entities. there no better way it.

datastore performance not depend on number of entities store, on number of entities retrieve.