2 Oracle NoSQL Database Data Model
In Oracle NoSQL Database, data is modeled as typed items. A typed item (or simply item) is a pair consisting of a data type and a value. A type is a set of possible values that may be stored in a database field (e.g. a table column) or be returned by some computation (e.g. during the evaluation of a query). In any item, the item value must be an instance of the item type. The values in this set are called the instances of the type. An item is said to be an instance of a type T if its value is an instance of T.
The Oracle NoSQL Database data model consists of various data types that allow for the storage and manipulation of hierarchical data. The Oracle NoSQL Database data types can be broadly classified into atomic types, complex types, JSON types, and wildcard types. Instances of atomic data types are single, indivisible units of data. Instances of complex data types contain multiple items and provide access to their nested items. JSON types contain the JSON objects in the name/value format. Wildcard types are similar to abstract supertypes in object-oriented programming languages. They combine instances of other data types and they are used to support data that do not have a fixed structure. This chapter describes each of these data types in detail.
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Data types describe the kind of data that can be stored in an Oracle NoSQL Database, as well as the kind of data generated during the evaluation of a query.This chapter contains the following topics: