Checkpoints

Not Supported

SurrealDB does not explicitly support checkpoints. However, SurrealDB internally uses other key-value store databases for storing user data and metadata in the backend. Some of these backends like RocksDB do support checkpointing and might create checkpoints in the background.

Data Model

Relational Document / XML Graph

SurrealDB supports relational, document, and graph-based data models. By default, SurrealDB creates schema-less documents, however the SurrealQL syntax provides functionality for creating fixed-schema tables as well. Graph-based models are constructed by representing the nodes and the edges as relations that are related by record links.

Foreign Keys

Not Supported

SurrealDB does not have the concept of foreign keys. It instead uses record links to link records in different relations like the edges of a graph.

Joins

Not Supported

SurrealDB does have the concept of joins. Instead of Joins between pre-defined relations, SurrealDB uses graph edges (record links) to link records to each other. With graph edges and the ability to store arrays and objects as field members, SurrealDB can provide the functionality of Joins along with other graph-based operations like path traversal.

Parallel Execution

Intra-Operator (Horizontal) Inter-Operator (Vertical)

SurrealDB allows a PARALLEL keyword to be added to most queries. This allows SurrealDB to spawn multiple threads to execute fetch and update operations. Using this SurrealDB is able to fetch data form relations in parallel by spawning one thread per relation. Further it is able to run the insert/update/delete operations for each row in parallel since it uses a row-by-row iteration model.

Query Compilation

Not Supported

SurrealDB does not have support for query compilation.

Query Execution

Tuple-at-a-Time Model

SurrealDB uses the volcano-style tuple-at-a-time model for query execution. However, while loading the data from the storage, SurrealDB tries to amortize the IO cost by loading 1000 data points at a time and then processing them one at a time as per the query requirements.

Query Interface

Custom API SQL HTTP / REST RPC

SurrealDB can be started as an independent process or embedded in the application as a library. As an independent process, it is possible to interact with the database using either the SurrealQL REPL (if SurrealDB is running locally), or using the HTTP/REST endpoints. As a library, SurrealDB can be used in other applications by interfacing with the APIs provided by the SurrealDB library. SurrealDB also provides the WebSocket API which can be interfaced with using RPCs.

Storage Architecture

Hybrid

SurrealDB can support 3 types of storage architectures: in-memory; on-disk; and distributed cloud. Since SurrealDB uses other key-value store databases to provide storage functionality, it is able to take advantage of all storage architectures supported by those key-value stores. Currently, the in-memory mode is supported using EchoDB. on-disk mode is supported through databases like RocksDB, and distributed cloud storage is supported by databases like TiKV.

Storage Model

Custom

SurrealDB does not implement its own storage layer. It relies on other key-value store databases to provide storage functionality for the user data and metadata. However, SurrealDB can only support key-value stores as the storage layer. All data in SurrealDB is eventually stored in the key-value format after internal processing.

Storage Organization

Copy-on-Write / Shadow Paging

Stored Procedures

Supported

SurrealDB provides constructs to store queries and functions in the database itself as futures. These queries/functions are executed whenever data is retrieved using the SELECT statements. Using these SurrealDB is able to support more functionality than just stored procedures.

System Architecture

Shared-Nothing Embedded