QuestDB

QuestDB is an open-source SQL database designed to process time-series data, faster. It uses a column-oriented approach, vectorized execution, SIMD instructions, and a whole array of low-latency techniques. The whole code base is built from scratch and without dependencies, in the name of performance. QuestDB is 100% free from garbage collection. QuestDB implements SQL, and augments it for time-series. It exposes a Postgres wire protocol, a high-performance REST API, and even supports ingestion with InfluxDB line protocol. It supports both relational and time-series joins, which makes it easy to correlate data over time. Writes are durably committed to disk, meaning that the data is safe - yet instantly accessible.

History

QuestDB was born as a side project from Vlad Ilyushchenko who applied principles from low latency techniques found in the financial services industry. QuestDB is backed by YCombinator and its recent [Hacker News launch](https://news.ycombinator.com/item?id=23975807) goes through the story of QuestDB since 2013.

Query Interface

SQL

QuestDB enhances ANSI SQL with time series extensions to manipulate time stamped data.

Concurrency Control

Timestamp Ordering

QuestDB uses a single writer model. The writer re-orders timestamps on the fly. Multi-publisher, single consumer queue provides concurrent write access.

Logging

Not Supported

Joins

Hash Join Semi Join

QuestDB supports the following types of joins: INNER, OUTER, CROSS, ASOF and SPLICE. FULL joins are not yet implemented and are on our roadmap. All supported join types can be combined in a single SQL statement; it is job of QuestDB SQL optimiser to determine best execution order and algorithms.

Storage Model

Decomposition Storage Model (Columnar)

QuestDB uses a column-based storage model. Data is stored in tables with each column stored in its own file and its own native format. New data is appended to the bottom of each column to allow data to be organically retrieved in the same order that it was ingested.

Stored Procedures

Not Supported

Indexes

Hash Table

Indexing is available for symbol columns. Index support for other types will be added over time.

Storage Architecture

Disk-oriented

Memory mapped files data access.

Foreign Keys

Not Supported

Data Model

Column Family Relational

QuestDB uses a relational model with column-based storage model.

System Architecture

Shared-Nothing Embedded

Query Compilation

JIT Compilation

Hardware Acceleration

Custom

SIMD optimised analytics.

Storage Organization

Log-structured

Parallel Execution

Inter-Operator (Vertical)

Multi threaded SQL execution.

QuestDB Logo
Website

https://www.questdb.io/

Source Code

https://github.com/questdb/questdb

Tech Docs

https://questdb.io/docs/introduction/

Developer

QuestDB

Country of Origin

GB

Start Year

2014

Project Type

Commercial, Open Source

Written in

C++, Java

Supported languages

C, C++, Go, Java, JavaScript, Python, R, Rust, SQL

Inspired By

Kdb+

Compatible With

InfluxDB, PostgreSQL

Operating Systems

Android, Linux, OS X, Windows

Licenses

Apache v2