The following list contains definitions specific for ThingsDB:
| Keyword | Definition |
|---|---|
| Collection | The collection is the root thing. Every collection has its own scope. |
| Computed properties | With computed properties it is possible to return computed values by wrapping a Type. |
| Closure | A Closure is a user defined method which can be saved. It can be used as a prepared piece of code or to consume items from a thing, list, tuple or set. |
| Change | ThingsDB creates a change when a query modifies something. Changes are applied in order by each node to guarantee consistency. |
| Function | Function in ThingsDB means a built in function. A function needs the exact number of arguments that is expected, which is different for a closure or procedure. |
| Node | Node is the process running ThingsDB. ThingsDB can work with a single node but is designed to work with multiple nodes. Running on at least three nodes brings redundancy and ensures the database stays operational. |
| Procedure | A procedure in ThingsDB is a named closure that is attached to a scope (@thingsdb or @collection) and available to use in an API call. |
| Relation | Relations can be created between Types or even within a single Type and can be used to create a two-way relation between instances. See mod_type, action: rel. |
| Scope | When sending a query, calling a procedure or subscribing to a thing, the request will require you to provide a scope. ThingsDB has three scope categories: @thingsdb, @node and @collection. |
| Thing | A thing is an object to which properties can be assigned. |
| Quorum | ThingsDB ensures consistency across multiple nodes. This is achieved by changes. Changes get an Id which are in applied order. Before a node can assign an Id to a change, it needs approval of the majority of the existing nodes. Once a node has connected to the others, it takes part in the quorum. If a node goes down it still gets accounted for, but will negatively influence the quorum as it cannot respond. When a node is deleted it does not take part in the quorum anymore. |
| Zone | When a node is in “away” mode, queries to a collection or ThingsDB scope will be forwarded to another node. If zones are configured, the node will first try a node within the same zone; only if no other node in the same zone is available, another node in another zone will be used. |