QuestDB API
High-performance open-source time-series database with PostgreSQL wire protocol compatibility, InfluxDB line protocol ingestion, and a REST API — optimized for fast SQL analytics over time-stamped data.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Community Edition has minimal authentication — no auth by default. TLS must be manually configured. Enterprise adds proper auth, RBAC, and TLS enforcement. Connection credentials in config files require careful secret management by agents. Public-facing installs must explicitly enable auth or data is exposed.
⚡ Reliability
Best When
You need SQL analytics over time-series data at extreme throughput and want PostgreSQL wire protocol compatibility for existing tooling — especially when InfluxDB's Flux language is a barrier.
Avoid When
You need ACID transactions, frequent row updates, or complex relational queries across many tables — use PostgreSQL or TimescaleDB instead.
Use Cases
- • Ingesting high-frequency agent telemetry and metrics via InfluxDB line protocol for fast SQL querying
- • Time-series analytics dashboards requiring sub-second SQL query response over billions of rows
- • Real-time monitoring of agent fleet performance (latency, error rates, throughput) with time-windowed aggregations
- • Financial tick data storage and OHLCV aggregations using SQL with native time-series functions
- • IoT sensor data ingestion at millions of rows per second with simultaneous analytical queries
Not For
- • Transactional OLTP workloads requiring row-level ACID guarantees and frequent updates — QuestDB is append-optimized
- • Teams without SQL knowledge who prefer PromQL or Flux query languages
- • Workloads requiring complex JOINs across many relational tables — QuestDB excels at time-series analytics, not general relational queries
Interface
Authentication
QuestDB OSS has minimal authentication — HTTP Basic Auth for the REST API and web console. PostgreSQL wire protocol uses username/password. QuestDB Enterprise adds LDAP, Kerberos, and role-based access control. QuestDB Cloud uses API tokens for the management plane. Default installs have no auth enabled — must be explicitly configured.
Pricing
Community Edition is Apache 2.0 licensed — fully free for commercial use. Enterprise adds cold storage tiering, replication, and enhanced security. Cloud provides fully managed deployment with automated backups.
Agent Metadata
Known Gotchas
- ⚠ Default installation has no authentication — agents connecting to an exposed QuestDB instance may access all data without credentials
- ⚠ The designated timestamp column is immutable after table creation — schema design must be correct from the start
- ⚠ Out-of-order ingestion (ILP) is supported but requires WAL mode to be enabled — older versions silently dropped out-of-order rows
- ⚠ REST API query endpoint (/exec) is synchronous and single-threaded per request — very large queries will block the HTTP interface
- ⚠ QuestDB does not support UPDATE or DELETE in standard SQL — data is append-only; workarounds require querying and re-inserting
- ⚠ Symbol columns (low-cardinality categoricals) must be declared at table creation — using strings instead of symbols dramatically increases memory usage
- ⚠ ILP ingestion errors are logged server-side but not returned to the client — agents must monitor server logs for ingestion failures
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for QuestDB API.
Scores are editorial opinions as of 2026-03-06.