# QuestDB

Open-source time-series SQL built for tick data — ASOF JOIN, SAMPLE BY, LATEST ON.

*https://stockmarketstack.com/tools/questdb · Tick Data Storage & Time-Series Databases*

## Facts

### At a glance

| Field | Value |
| --- | --- |
| Vendor | QuestDB |
| Category | Tick Data Storage & Time-Series Databases |
| Job | tick_storage |
| Website | https://questdb.com |
| Pricing model | subscription |
| Free tier | true |
| Open source | true |
| Licence | Apache-2.0 |
| Self-hosted | true |
| Tested hands-on | false |
| Last updated | 2026-09-13 |

### Pricing

| Tier | USD | Period |
| --- | --- | --- |
| Open Source | 0 USD | month |
| Enterprise | on request | — |

### Coverage

| Field | Value |
| --- | --- |
| Asset classes | none |
| Markets | none |
| Works outside the US | false |
| Data latency | none |
| Platforms | web, cli |
| AI features | assistive |

### Interfaces

| Field | Value |
| --- | --- |
| API | true |
| Webhooks | false |
| Scripting | SQL |
| Python | true |
| Spreadsheet add-in | false |
| MCP server | true |
| Export | csv, json, parquet, api |

### Capabilities

Yes: charting

No: screening, scanning, backtesting, automation, live_trading, paper_trading, portfolio_tracking, broker_import, tax_reporting, alerts, news, options_analysis

*Verified: pricing 2026-09-13; capabilities 2026-09-13; coverage 2026-09-13.*

## What it is

QuestDB is a column-oriented time-series database you run yourself, queried in SQL with a handful
of extensions that exist because generic SQL handles market data badly:

- **`ASOF JOIN`** matches each row to the most recent row in another table at or before its
  timestamp — trades to the quote that was live when they printed — with an optional `TOLERANCE`
  clause that rejects a match too stale to mean anything. In Postgres that is a lateral subquery per
  trade, or a window function over a union of both tables.
- **`LT JOIN`** is the same, strictly earlier: what you want when the quote update and the trade
  share a timestamp and you must not see the quote the trade caused.
- **`SAMPLE BY 5m`** builds bars, with calendar or first-observation alignment, a time zone and
  `FILL(PREV | LINEAR | NULL | NONE)` for empty buckets — in place of `date_trunc`, `GROUP BY` and a
  generated series to find the gaps.
- **`LATEST ON ts PARTITION BY symbol`** returns the last row per instrument without the
  `DISTINCT ON` or window-function trick, and stops scanning once it has found one row per symbol.

Ingestion is built for feeds, not transactions: rows arrive out of order and are merged into place,
tables and columns are created from the first row, and retried writes can be deduplicated on commit.
Version 10.0.0, released 6 August 2026, introduced QWP, a binary columnar WebSocket protocol
carrying ingest and query results on the HTTP port; InfluxDB Line Protocol over HTTP or TCP and the
Postgres wire protocol still work and are now documented as compatibility protocols. The vendor's
own figure is "over 8M rows/sec per server, even through dedup and out-of-order indexing" —
QuestDB's benchmark, not an independent one.

## Pricing

Two products, one engine. The open-source build is Apache-2.0, costs nothing at any scale, and that
is the whole of it: single instance, community support, an admin user plus one configurable
read-only user, basic auth over unencrypted transport. Enterprise adds replication with sub-100ms failover, read replicas, TLS on every protocol,
column-level RBAC, SSO, audit logs, incremental snapshots to object storage, point-in-time recovery
and hot/cold tiering to Parquet and Iceberg on S3, Azure Blob or GCS under the same SQL. Its price
is not published — the site has no pricing page at all, only an Enterprise contact form and a trial
of unstated length — and there is no self-serve managed tier to fall back on.

## Data & coverage

QuestDB ships no market data of any kind. It is storage and a query engine; the ticks are yours to
source and yours to load.

## Integrations

First-party clients for Java, C/C++, Rust, Python, .NET and Go on the new protocol, Node.js on ILP,
PHP and R through PGWire. REST endpoints cover query to JSON, export to CSV or Parquet, and CSV
upload. The bundled Web Console is a query editor with Jupyter-style notebooks, nine chart types
including candlestick, and dashboards that refresh on a schedule; its AI assistant writes and
explains SQL on your own OpenAI or Anthropic key, which stays in the browser. QuestDB also publishes
an MCP server — `@questdb/mcp-server-questdb` on npm, Apache-2.0, 0.4.0 as of 20 August 2026 —
giving a coding agent schema access, SQL execution and notebook building.

## Limitations

- **No `DELETE`.** Rows leave by dropping or expiring a partition via TTL, not by predicate. `HAVING`,
  `OFFSET`, `DISTINCT ON`, `ON CONFLICT` and correlated subqueries in `WHERE` are also absent, and
  cursors are forward-only — enough Postgres compatibility to connect, not enough to port a schema.
- **The open edition is one machine**, with no replication, failover, read replicas or tiered
  storage; backups are full and local and recovery is from the last one. It also does no encryption
  on any protocol, PGWire included — on an untrusted network that means a proxy or Enterprise.
- **Compression is somebody else's job**: the documented route is ZFS with LZ4 or zstd underneath,
  and no ratio for tick data is published.
- **It is a database to operate.** Production needs `ulimit -n` and `vm.max_map_count` raised to
  1048576 or you hit errno=24 and errno=12 under load, NVMe or 7000+ IOPS of network storage, 8GB of
  RAM minimum, and a filesystem that is not NFS — that one is explicitly unsupported.
- `LATEST ON` partitioned by more than one column scans the whole table and degrades on hundreds of
  millions of rows. `TOLERANCE` accepts nanoseconds through weeks, but not months or years.
- Enterprise pricing is unknowable before a sales call, and there is no self-serve managed plan.

## Alternatives

[ClickHouse](https://stockmarketstack.com/tools/clickhouse) if the workload is wide analytical scans rather than joins on time, and you accept
writing the as-of logic yourself. [TimescaleDB](https://stockmarketstack.com/tools/timescaledb) if being actual Postgres — extensions, transactions,
`DELETE`, the ecosystem — matters more than time-series syntax. [kdb+](https://stockmarketstack.com/tools/kdb) if the budget exists and the
requirement is single-digit microseconds. DuckDB over Parquet files if the data fits on one machine
and nothing streams in live.

## FAQ

### Is QuestDB free?

The open-source edition is, under an unmodified Apache-2.0 licence — no Commons Clause, no BSL, commercial use included. What it does not include is replication, failover, RBAC, TLS or tiered storage; those are QuestDB Enterprise, whose price the vendor does not publish anywhere.

### Can I buy managed QuestDB hosting?

Not self-serve. As of 13 September 2026 questdb.com/pricing and questdb.com/cloud both redirect to the Enterprise page, no page on the site quotes an hourly or monthly instance rate, and the managed route offered is Bring Your Own Cloud — QuestDB's team operates the database inside your own AWS or Azure account under an Enterprise contract.

### Does QuestDB come with market data?

No. It is an empty database. Every trade, quote and bar in it is one you ingested yourself from a broker, an exchange feed or a market data vendor.

### Is QuestDB a drop-in replacement for PostgreSQL?

No, and the wire protocol makes that easy to misread. QuestDB speaks PGWire, so psql and most Postgres drivers connect, but the SQL dialect has no DELETE, no HAVING, no OFFSET or DISTINCT ON, no ON CONFLICT and no correlated subqueries in WHERE, cursors are forward-only, and the open-source build does not do SSL on that port.

## Also worth comparing

- [ArcticDB](https://stockmarketstack.com/tools/arcticdb.md) — Versioned Pandas frames written straight onto S3, with no server to run.
- [DolphinDB](https://stockmarketstack.com/tools/dolphindb.md) — Closed-source tick database with a vector language, as-of joins and streaming engines.
- [InfluxDB 3](https://stockmarketstack.com/tools/influxdb.md) — Line-protocol time-series database rewritten on Arrow, DataFusion and Parquet.
- [kdb+](https://stockmarketstack.com/tools/kdb.md) — The tick database trading desks have run for 25 years, queried in q rather than SQL.
- [OneTick](https://stockmarketstack.com/tools/onetick.md) — Enterprise tick capture, storage and streaming analytics, sold only by quote.
- [Apache Druid](https://stockmarketstack.com/tools/druid.md) — Real-time OLAP cluster built for high-concurrency dashboards, not for research joins.