FIELD(name)
Non-indexed field with specified name.

KEY(name, index_type)
Indexed field. index_type should be a combination of HASHED and INDEXED flags. When the HASHED flag is specified, FastDB will create a hash table for the table using this field as a key. When the INDEXED flag is specified, FastDB will create a (special kind of index) T-tree for the table using this field as a key.

RELATION(reference, inverse_reference)
Specifies one-to-one, one-to-many or many-to-many relationships between classes (tables). Both reference and inverse_reference fields should be of reference or of array of reference type. inverse_reference is a field of the referenced table containing the inverse reference(s) to the current table. Inverse references are automatically updated by FastDB and are used for query optimization