• @ManyToOne - object references.
• @OneToMany - collections.
• @MappedSuperClass - Useful timestamping class and for a common ID.
• @Inheritance
• @Lob - stores lobs in S3 so make it as big as you want (up to 5GB).
• @Id - Assigns UUID automatically
• Lazy loading on ManyToOne, Lobs and OneToMany so only hits SDB on an as needed basis.
• Rudimentary caching to reduce hits on SDB
• JPA Queries
• Perst All-Java Embedded Database Adds KD-Tree Indexes

McObject provides support for the KD-Tree. A KD-Tree is a database index that is used in spatial and pattern-matching applications, to Perst. It is an open source, object-oriented all- Java embedded database system. Developers who have been working with Perst, the KDTree helps them in expanding coding efficiency
and helps in making Java data objects easier to use in certain types of application.

The new k-dimensional tree or in short KD-Tree index enables us to add a structure in Perst for storing and manipulating point objects in a kdimensional space by partitioning that space. These are practically used in computer graphics, geographical information systems and biometric applications like fingerprint matching as well as
their efficiency in handling multi-dimensional data, KD-trees helps the developers in "normal" applications where query predicates include different combinations of object fields.

McObject's Perst embedded database and eXtremeDB embedded database provides a collection various index types, including:

• B-trees used in common sorting, searching, insertions, and deletions
  
• R-trees used for geospatial indexing (mainly in GPS/navigation systems)
  
• T-trees used in all-in-memory data storage and accessHash tables for quickly locating a single unique index entry
  
• Patricia trie index, that is used for speedly searching in networking and telephony applications
  
• Custom indexes used in b-trees allowing to the application to define the collating sequence of entries; it is also useful in implementing soundex algorithm searches, for example
  
• Bit or bitmap used for optimizing the indexes for columns in which values repeat frequently
  
• TimeSeries class used in dealing efficiently with small fixed-size objects
  
• Specialized versions of collections used in thick indices (indexes having multiple duplicate values), and bit indexes
  
• KD-Tree is developed by using the latest versions of Perst for Java and .NET. It is available for free download
  at McObject’s Web site.