Schema

Every Datom added to Triplox is validated by a schema. The schema itself is described by entities. Schema is data and no different in terms of storage then standard entities. A schema entity has the following attributes:

Attribute	Description	Required?
:db/ident	A unique name or identifier for an entity. Usually this is a schema entity.	Yes
:db/valueType	Defines the type of value associated with an attribute.	Yes
:db/cardinality	Weather a attribute does have a single or multiple values.	Yes
:db/unique	Defines a uniqueness constraints for values associated with an attribute.	No

:db/ident

:db/ident is a unique keyword identifying an entity. In most cases it is used to identify attributes in queries, but :db/ident can also be used to define an enum like collection of possible values. Examples are the values of :db/valueType and :db/cardinality below or the value of :db/txResult

For :db/ident it is recommended to prefix identifiers with the general entity class that an attribute is going to be used for. Meaning it is discouraged to use :name for the name of people and the name of products and instead use two attributes :person/name and :product/name. This avoids confusion and also gives better index locality when joining.

:db/valueType

Allowed value types:

ident	Description
:db.type/keyword	EDN keyword
:db.type/string	UTF-8 string
:db.type/long	64-bit signed integer
:db.type/ref	Entity reference (same encoding as Long; schema-only distinction)
:db.type/boolean	true / false
:db.type/double	64-bit IEEE 754 float
:db.type/float	32-bit IEEE 754 float
:db.type/instant	Timestamp (microseconds since epoch)
:db.type/uuid	128-bit UUID
:db.type/bytes	Arbitrary binary data
:db.type/bigint	Arbitrary precision integer
:db.type/vector	Ordered collection
:db.type/map	String-keyed map

:db/cardinality

Cardinality can take two values:

ident	Description
:db.cardinality/one	An entity has at most one value for this attribute.
:db.cardinality/many	An entity may have multiple values for this attribute.

:db/unique

Unique attributes are indexed by value and checked during transaction processing.

ident	Description
:db.unique/value	At most one entity may assert a given value. No lookup refs or upserts.
:db.unique/identity	Same uniqueness constraint, plus lookup refs and identity upsert.

Only :db.unique/identity attributes participate in tempid upsert resolution. :db.unique/value is a constraint only: transactions may assert it, but they cannot use it to resolve lookup refs or adopt an existing entity for a tempid.