Querying

db4o supplies three querying systems, Query-By-Example (QBE),Native Queries (NQ), and the SODA Query API.

Queries-By-Example (QBE) are appropriate as a quick start for users who are still acclimating to storing and retrieving objects with db4o, but they are quite restrictive in functionality.

Native Queriesupdated (NQ) are the main db4o query interface, recommended for general use.

The SODA Query API is the underlying internal API. It is provided for backward compatibility and it can be useful for dynamic generation of queries, where NQ are too strongly typed. There may be queries that will execute faster in SODA style, so it can be used to tune applications.

Of course, you can mix these strategies as needed.

For more information on custom query comparators see Custom Query Comparator