Question

In Java Web Application, i would like to know if it is a proper (or “standard”?) way that all the essential data such as the config data, message data, code maintenance data, dropdown option data and etc (assuming all data will not updated frequently) are loaded as a “static” variables from database when the server startup.

Or is it more preferred way to retrieve data by querying db per request?

Thanks for all your advice here.

Answer 1

It is perfectly valid to pull out all the data that are not going to be modified during application life-cycle into and keep it in memory as singleton or something.

This is a good idea because it saves DB hits and retrieval is faster. A lot of environment specific settings and other data can also be pulled once and kept in an immutable hashmap for any future request.

In a common web-app you generally do not have so many config data/option objects that can eat up lot of memory and cause OOM. But, if you have a table with hundreds of thousands of config data, better assume pulling objects as and when requested. And if you do want to keep it in memory, think of putting this in some key-value store like MemcacheD.