Datomic Differences

Although datahike supports a part of Datomic's API, some behavior is different using the different functions. Datahike supports part of the datomic.client.api:

Without differences you may use the following like in Datomic:

• as-of
• history
• pull
• q
• since

The following functions from the datahike.api namespace are different from Datomic's client API:

• connect
• create-database
• datoms
• db
• delete-database
• transact
• with

Additionally, datahike supports also almost all functions from datascript in the datahike.core namespace.

connect

Connects to an existing database given a URL or host configuration hash-map. The schema for the URL and hash-map can be found here.

(connect "datahike:mem://datomic-diff")

create-database

Creates a new database given a URL or configuration hash-map with additional optional parameters for schema-on-read and temporal-index capabilities. Have a look at the configuration documentation for details.

(create-database "datahike:mem://datomic-diff" :schema-on-read true
:temporal-index false)

datoms

The signature is different. Index can be selected: :eavt, :aevt, :avet and components to be matched using entity, attribute and values. Find more examples and documentation either in the examples project or in the code documentation.

(datoms @conn :eavt :name)

db

Since the database can be just de-referenced from the connection this function is just a small wrapper for Datomic compliance.

(db conn)

delete-database

The deletion supports only URIs at the moment.

transact

Returns a different hash map as a report. Have a look at the clojure docs for more examples.

with

Applies transactions to an immutable database value and returns a new database snapshot. It does not change the mutable database inside the connection unlike transact.