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:

• kdb+ algorithm

• gzip

• Google Snappy

• lzh4c

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.

Query Compilation

Not Supported

q is interpreted language.

Data Model

Relational

Kdb+ uses relational model.

Query Interface

SQL HTTP / REST

Kdb+ supports following interfaces:

• ODBC/JDBC

• C/C++

• Java

• C#

• Python

• R

Indexes

B+Tree

Kdb+ supports secondary indexes.

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.

Stored Procedures

Supported

Kdb+ supports UDF.

Query Execution

Vectorized Model

q is vector processing languages.

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.

Storage Model

Decomposition Storage Model (Columnar)

Kdb+ uses DSM both for in-memory and on-disk storage.

Views

Not Supported

Hardware Acceleration

Custom

Kdb+ doesn't rely on any hardware acceleration.

Isolation Levels

Serializable

Kdb+ only supports SERIALIZABLE isolation level.