All data objects in the platform have attributes. An attribute provides information (metadata) about an object. NoSQL table-item attributes in the platform are the equivalent of columns in standard NoSQL databases. See Working with NoSQL Data, including a terminology comparison. For the supported attribute data types, see the Attribute Data Types Reference.
Attributes are classified into three logical types:
- User attributes
- Attributes that the user assigns to a data object using the platform APIs.
- System attributes
- Attributes that the platform automatically assigns to all objects.
The system attributes contain the object's name (
__name) and miscellaneous information that was identified for the object by the system, such as the UID ( __uid) and GID ( __gid) of the object's owner, and the object's last-modification time __mtime_secs. For a full list of the supported system attributes, see the System-Attributes Reference.
- Hidden attributes
- Attributes that the user or platform optionally assign to an object and are used to store internal information that is not meant to be exposed.
__) to differentiate them from user attributes.
Attribute names are subject to the general file-system naming restrictions and the following additional restrictions:
Contain only the following characters:
- Alphanumeric characters (a–z, A–Z, 0–9)
- Underscores (_)
Begin either with a letter (a–z, A–Z) or with an underscore (_)
Not identical to a reserved name — see Reserved Names
Length of 1–255 characters