Desktop App w/ Database - How to handle data retrieval?

Imagine to have a Desktop application - could be best described as record keeping where the user inserts/views the records - that relies on a DB back-end which will contain large objects' hierarchies and properties. How should data retrieval be handled?

Should all the data be loaded at start-up and stored in corresponding Classes/Structures for later manipulation or should the data be retrieved only at need, stored in mock-up Classes/Structures and then reused later instead of being asked to the DB again?

As far as I can see the former approach would require a bigger memory portion used and possible waiting time at start-up (not so bad if a splash screen is displayed), while the latter could possibly subject the user to delays during processing due to data retriev开发者_Python百科al and would require to perform some expensive queries on the database, whose results and/or supporting data structures will most probably serve no purpose once used*.

Something tells me that the solution lies on an in-depth analysis which will lead to a mixture of the two approaches listed above based on data most frequently used, but I am very interested in reading your thoughts, tips and real life experiences on the topic.

For discussion's sake, I'm thinking about C++ and SQLite.

Thanks!

*assuming that you can perform on Classes/Objects faster operations rather than have to perform complicated queries on the DB.

EDIT

Some additional details:

• No concurrent access to the data, meaning only 1 user works on the data which is stored locally.
• Data is sent back depending on changes made humanly - i.e. with low frequency. This is not necessarily true for reading data from the DB, where I can expect to have few peaks of lots of reads which I'd like to be fast.
• What I am most afraid of is the user getting the feeling of slowness when displaying a complex record (because this has to be read in from the DB).

Use Lazy Load and Data Mapper (pg.165) patterns.

I think this question depends on too many variables to be able to give a concrete answer. What you should consider first is how much data you need to read from the database in to your application. Further, how often are you sending that data back to the database and requesting new data? Also, will users be working on the data concurrently? If so, loading the data initially is probably not a good idea.

After your edits I would say it's probably better to leave the data at the database. If you are going to be accessing it with relatively low frequency there is no reason to load up or otherwise try to cache it in your application at launch. Of course, only you know your application best and should decide what bits may be loaded up front to increase performance.

You might consider to user intermediate server (WCF) that will contain cached data from the database in memory, this way users don't have to go every time to the database. Also since it is only one access point to for all users if somebody changes/added record you can update cache as well. Static data can be reloaded every x hours (for example every hour). It still might not the best option, since data needs to be marshaled from Server to the Client, but you can use netTcp binding if you can, which is fast and small.