Object Databases
From a pure object-oriented perspective, object databases provide a nice fit for object-oriented development. Object databases are available that provide APIs and query languages that can be used for Java. While these tools do provide a convenient facility for persisting objects in Java, they generally do not provide a standardized query language, and they begin to experience performance issues as the size of the data set grows larger and queries against the data become more complex.
Object database management systems (ODBMS) have always enjoyed some degree of popularity in some information technology (IT) sectorsfor example, finance and researchbut for various reasons, these databases do not currently enjoy the popularity of relational databases.