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Usage Pitfalls

The db4o team tries hard to make the db4o as easy to use as possible. However there are still some pitfalls.

When objects are only partially loaded and you run into null pointer exceptions, then you ran into not activated objects. This is a common issue. See "The Activation Pitfall"

When updates are not stored then you have issues with the update-depth.See "Update Depth Pitfall"

db4o tries hard to store every object without any mapping. However in practice the mapping is not perfect. For UUID you should add a configuration to support them propertly. See "UUID Support". For big math types you need some additional configuration See "Storing BigDecimal And BigInteger". Also be careful with collections and avoid SQL-Types. See "Special Type Handling"

In more complex Java environments you may run into class loading issues. See "Classloader And Generic Classes"

There are a few dangerous practices which you really should avoid. See "Dangerous Practices"

db4o has database size limit, which is by default 2 GByte. See how you can increase it. See "Working With Large Amounts Of Data"