Containers

What is a container?

A container is the third level in the Objectivity/DB logical storage hierarchy, existing as a component of a database. Containers organize the data within a database. A container is physically stored either within a database file or in its own separate container file. Administering a container mainly involves updating the storage characteristics of container files to help you better utilize your disk and network resources.

Physically, the binary representations of a container and its basic objects are stored in one of two ways:

➤ For an embedded container, these representations are stored within the file of the database to which the container belongs.
➤ For an external container, these representations are stored in a separate container file.

Whereas every database is stored as a separate file, individual containers are designated as either embedded or external by the database designer. Normally, embedded containers are used, unless their aggregate size exceeds the practical capacity of a single database file. A database can have any combination of external containers and embedded containers to keep the database file size manageable.

What are the container properties?

Container properties apply to both embedded containers and external containers, they include the following:

➤ The container and its properties are listed in this database’s catalog of containers.
➤ Each container has a unique identifier — the unique integer identifier within the scope of the containing database.
➤ A container can have a system name — unique logical name of the container within the scope of the containing database. A container with no system name is identified by its integer identifier.
➤ File host — the host machine on which the container file resides.
➤ File path — the container file’s pathname and filename.
➤ Storage page size — the size (in bytes) of the storage pages in the container.
➤ Growth factor — the amount by which a container’s size can be increased to accommodate more basic objects, expressed as a percentage of its current number of storage pages.

How do I create/use containers?

A container is normally created by an Objectivity/DB application, which designates the container as embedded or external, and specifies the container’s properties.

For examples of how to create and use containers visit our How To's section.