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What QuestDB is
QuestDB describes itself as an open source time-series database engineered for low latency, built on a column-oriented, time-partitioned storage engine with memory-mapped files and vectorized execution.
It is a SQL database rather than a bespoke query language. What makes it a time-series database is that one column is privileged as the designated timestamp, and both the storage layout and the SQL dialect are built around it.
The time-series extensions are the reason it is in the stack: SAMPLE BY for time bucketing, LATEST ON for the most recent row per series, and ASOF JOIN for joining series that do not share timestamps.
What it is normally used for
How QuestDB is used generally, before Synedrix OS enters the picture.
- Capital markets: tick data, pre- and post-trade analytics, order book replay
- Aerospace: real-time monitoring of in-flight systems and predictive maintenance
- Energy infrastructure: SCADA and grid telemetry ingestion
- Machine and fleet telemetry: robotics and fleet observability
- Financial services operations: fraud detection and retail banking analytics
What it owns, and what it does not
Every platform in the stack has a non-overlapping responsibility. The boundary is as much a part of the design as the capability.
Owns
- High-volume time-series records
- Materialised temporal aggregations
- Trend and seasonality query support
- Historical event windows
- Agent execution durations, token and cost over time, tool latency, and event volumes
Does not own
- Business entities, workflow state, audit-grade records
- → Supabase PG17 (Layer 7)
- LLM trace spans, prompt versions, per-call cost attribution
- → Langfuse (Layer 10)
- Threshold breaches, alert routing, dashboards
- → Grafana LGTM Stack (Layer 10)
- Workflow and outcome lineage
- → Neo4j (Layer 7)
- Semantic retrieval and pattern recall
- → Qdrant (Layer 7)
- Hot state, idempotency keys, heartbeats
- → Redis (Layer 7)
Why QuestDB
Built for constant high-volume data, not repurposed for it
Synedrix OS already has a general-purpose database for its core records. What it needed was something that could absorb a continuous, high-volume stream of telemetry without slowing that main store down, which is exactly what QuestDB is built for.
It speaks the same query language as the rest of the stack
QuestDB's time-series features are added on top of ordinary SQL, not a separate query language to learn, and because it's wire-compatible with Postgres, existing tools and clients work with it unchanged.
Trend data stays up to date automatically
A materialized view can be defined once, over a time-bucketed query, and QuestDB keeps it current automatically: no separate job needs to recompute it, which is exactly what the observability spec requires.
Old data ages out automatically, by policy
Data is stored in time-based partitions with an expiry attached. Old data is dropped as a fast directory operation, on a schedule set by policy, rather than through slow, one-row-at-a-time deletes.
Licence position
QuestDB questions, answered
Short, citable answers drawn from this page.
What role does QuestDB play in Synedrix OS?
QuestDB (Time-series engine) is mapped to Layer 7: Memory & Data in Synedrix OS. The time axis as a first-class citizen, queried in ordinary SQL.
What does QuestDB own in Synedrix OS?
QuestDB owns: High-volume time-series records; Materialised temporal aggregations; Trend and seasonality query support; Historical event windows; Agent execution durations, token and cost over time, tool latency, and event volumes.
What does QuestDB not own in Synedrix OS?
QuestDB does not own: Business entities, workflow state, audit-grade records (owned by Supabase PG17 (Layer 7)); LLM trace spans, prompt versions, per-call cost attribution (owned by Langfuse (Layer 10)); Threshold breaches, alert routing, dashboards (owned by Grafana LGTM Stack (Layer 10)); Workflow and outcome lineage (owned by Neo4j (Layer 7)); Semantic retrieval and pattern recall (owned by Qdrant (Layer 7)); Hot state, idempotency keys, heartbeats (owned by Redis (Layer 7)).
What licence is QuestDB under?
QuestDB is released under Apache 2.0. The licence is accurate, but replication is Enterprise-only. QuestDB is required in all three deployment modes, and the Apache 2.0 core provides no built-in high availability or disaster recovery: a single-node instance is a single point of failure for every trend series, SLO window, and materialised view. Role-based access control, automated backups, and storage tiering are also Enterprise-only.
The full reference page, with the operating model, deployment detail, and links to every canonical specification this platform touches, lives in the documentation repository, which is private while the platform is being built.