System Architecture

Shared-Nothing

Kdb+ uses Lambda architecture has the following properties:
- Data currently using stores in memory, while historical data is stored on disk.
- New data come in from streaming sources.
- Event-engine distribute data to downstream subscribers, including real-time database engine and streaming query engine. - Real-time database projects its content down to on-disk historical database for analytic use at daily basis, controlled by event-engine.

Logging

Physical Logging

Kdb+ uses physical logging. When new data comes from sources, in-memory event-engine will log to on-disk log file to ensure durability.

Hardware Acceleration

Custom

No hardware acceleration.

Query Compilation

Not Supported

q is interpreted language.

Indexes

B+Tree

Kdb+ supports secondary indexes.

Query Execution

Vectorized Model

Storage Architecture

Hybrid

Kdb+ has both in-memory and on-disk storage. New data is held in memory and is flushed to disk at daily basis under control of the event-engine.

Storage Model

Decomposition Storage Model (Columnar)

Views

Not Supported

Data Model

Relational

Stored Procedures

Supported

Compression

Naïve (Record-Level)

Kdb+ supports compression in following ways:
- A built-in WebSocket server which supports WebSocket compression standard.
- In-flight compression between hosts.
- On-disk compression, which supports 4 algorithms: 1) kdb+ algorithm 2) gzip 3) Google Snappy 4)lzh4c

Isolation Levels

Serializable

Kdb+ only supports SERIALIZABLE isolation level.

Query Interface

SQL

Kdb+ supports following interfaces:
- ODBC/JDBC
- C/C++
- Java - C# - Python
- R - Kafka