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.

Data Model

Relational

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

Foreign Keys

Not Supported

Hardware Acceleration

Custom

SIMD optimised analytics.

Indexes

Hash Table

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

Isolation Levels

Read Committed Repeatable Read Read Stability

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.

Logging

Not Supported

Parallel Execution

Inter-Operator (Vertical)

Multi threaded SQL execution.

Query Compilation

JIT Compilation

Query Execution

Vectorized Model

SIMD-based vector execution of queries.

Query Interface

SQL

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

Storage Architecture

Disk-oriented

Memory mapped files data access.

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.

Storage Organization

Log-structured

Stored Procedures

Not Supported

System Architecture

Shared-Nothing Embedded

Views

Not Supported