questdb
QuestDB is an open-source, columnar time-series database written in Java and C++ that prioritizes low-latency ingestion and SQL queries for financial and sensor data. It supports multi-tier storage, Postgres wire protocol, REST APIs, and scales to millions of events per second with minimal resource overhead.
Key facts
Objective fields from the source. Values we can't verify are shown as “Unknown” rather than guessed.
| Field | Value |
|---|---|
| Repository | questdb/questdb |
| Owner | questdb |
| Primary language | Java |
| License | Apache-2.0 — OSI-approved |
| Stars | 17.2k |
| Forks | 1.6k |
| Open issues | 865 |
| Latest release | 9.4.3 (2026-06-15) |
| Last updated | 2026-07-08 |
| Source | https://github.com/questdb/questdb |
What questdb is
Purpose-built TSDB with zero-GC Java/C++ core, SIMD-accelerated parallel query execution, and WAL → native columnar → Parquet storage tiering. Ingests via InfluxDB Line Protocol, exposes PGwire and REST interfaces, and includes time-series SQL extensions (ASOF JOIN, WINDOW JOIN, SAMPLE BY, LATEST ON) for financial analytics.
Get the questdb source
Clone the repository and explore it locally.
git clone https://github.com/questdb/questdb.gitcd questdb# follow the project's README for install & configurationNeed it deployed, integrated, or customized instead? DEV.co ships production installs.
Best use cases
Implementation considerations
- Schema design must account for time-series partitioning and cardinality; column-oriented layout favors wide, sparse schemas with many numeric metrics over deeply nested structures.
- Ingestion via InfluxDB Line Protocol or REST; choose client library matching your stack (Python, Go, Node.js, Java, Rust, .NET, C/C++ available). Batch sizes and concurrency tuning affect throughput.
- Multi-tier storage (WAL → native → Parquet) requires planning retention windows and tiering policies; monitor WAL size and native partition compaction in production.
- Query patterns differ from SQL OLTP: time-series functions (ASOF JOIN, SAMPLE BY, LATEST ON) require application logic refactoring; traditional SQL subqueries may have performance implications.
- Capacity planning for cardinality, ingestion rate, and query concurrency; built-in Web Console for management and monitoring, but production requires external observability (metrics, logs).
When to avoid it — and what to weigh
- Transactional ACID Requirements — QuestDB is optimized for append-heavy, read-heavy analytics workflows. If you need complex multi-row transactions, row-level locking, or strong ACID guarantees across arbitrary schemas, a traditional RDBMS is more appropriate.
- Ad-Hoc, Unstructured Data — Time-series databases assume time-ordered, append-only data with defined schema. General-purpose document stores or schemaless databases are better for exploratory, highly variable workloads.
- Very Small Datasets or Infrequent Queries — Operational overhead and columnar storage tuning are wasted on lightweight use cases. SQLite, PostgreSQL, or MySQL are simpler and more cost-effective for low-volume, sporadic access patterns.
- High Availability Without Enterprise License — Open-source QuestDB lacks built-in replication and failover; HA/read replicas are Enterprise features. Self-managing HA requires external clustering solutions and operational complexity.
License & commercial use
Apache License 2.0 (Apache-2.0) is a permissive OSI-approved license. Grants perpetual, worldwide, royalty-free rights to use, modify, and distribute the software, subject to license retention and liability disclaimers. No patent retaliation clause.
Apache-2.0 explicitly permits commercial use, modification, and redistribution. However, the license does not include warranties, SLAs, or vendor support. Enterprise edition (distinct product with HA, RBAC, TLS, support SLAs) is available separately under commercial terms; review enterprise license before adopting for production SLA-critical workloads.
DEV.co evaluation signals
Editorial assessment — not user reviews. Directional, with an explicit confidence level.
| Signal | Assessment |
|---|---|
| Maintenance | Active |
| Documentation | Strong |
| License clarity | Clear |
| Deployment complexity | Low |
| DEV.co fit | Strong |
| Assessment confidence | High |
Open-source code auditable; Apache-2.0 license includes liability disclaimer. Security features noted in Enterprise tier: TLS encryption, role-based access control (RBAC). Open-source version lacks built-in auth/encryption; network isolation and external authentication layer required for sensitive deployments. No known critical CVE details provided in data; review security advisories and apply patches regularly.
Alternatives to consider
InfluxDB
Purpose-built TSDB with Go implementation; strong Grafana integration. Weaker on complex SQL and financial analytics; higher operational cost at scale. Data format lock-in unless using recent OSS editions.
TimescaleDB
PostgreSQL extension for time-series; familiar SQL dialect and ACID transactions. Slower ingestion and query latency than QuestDB for high-cardinality workloads; less purpose-optimized for financial tick data.
Kdb+ (kdb.com)
Domain-leading time-series database for finance; proprietary, closed-source, expensive. Superior performance on some benchmarks but vendor lock-in, high licensing cost, and smaller ecosystem compared to QuestDB OSS.
Build on questdb with DEV.co software developers
Evaluate QuestDB for your time-series workload with our deployment guides (Docker, AWS, GCP) and live demo. Start with Docker: docker run -p 9000:9000 -p 9009:9009 -p 8812:8812 questdb/questdb. For production HA and enterprise support, contact the QuestDB team.
Talk to DEV.coRelated on DEV.co
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questdb FAQ
Can I use QuestDB in production without Enterprise support?
How does QuestDB handle out-of-order and duplicate data?
What is the learning curve for migrating from SQL to QuestDB?
Does QuestDB support real-time data federation with other systems?
Software development & web development with DEV.co
Adopting questdb is usually one piece of a larger software development effort. As a software development agency, DEV.co provides software development services and web development expertise — pairing senior software developers and web developers with your team to design, build, and operate open-source databases software in production.
Ready to Deploy QuestDB?
Evaluate QuestDB for your time-series workload with our deployment guides (Docker, AWS, GCP) and live demo. Start with Docker: docker run -p 9000:9000 -p 9009:9009 -p 8812:8812 questdb/questdb. For production HA and enterprise support, contact the QuestDB team.