An open source multi-tool for exploring and publishing data https://datasette.io
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Claude da523c30e5
Torture harness, and the fixes it found
tests/connection_torture.py drives one Datasette from several event loops
(threads) with the smallest pool, 1ms idle timeout and 10ms schema polling
through every connection operation, plus add/remove_database, scratch
databases, external schema changes, replaced/deleted files, cancellation,
Database.close()/Datasette.close() mid-flight and non-threaded mode. One
scenario per process, so crashes and hangs are results. It checks for hangs,
crashes, undocumented exceptions, per-database write order, lost writes,
read-your-writes, catalog freshness, and fds/threads/the instance released
after close(). tests/test_connection_torture.py runs a short fixed-seed
subset of every scenario.

Fixes for what it found:
- A cursor that left the thread owning its connection (the cursor returned
  by execute_write_many()/execute_write_script(), one returned by a write
  callback, one rejected by execute_fn(), or one held by an exception's
  frames) could be freed on the event loop thread while the connection ran
  the same SQL again; on Python < 3.12 freeing it resets the shared cached
  statement, and the other query failed with "bad parameter or other API
  misuse". Such cursors are now closed on the owning thread. Pre-existing on
  main (51 failures per 1,800 multi-loop execute_write_many calls).
- invoke_startup() is single-flight across event loops (a concurrent.futures
  future, datasette.utils.inflight) instead of _startup_sequence() holding
  an asyncio.Lock: a second loop got "bound to a different event loop" or
  hung, and two loops could run the startup hooks twice. A request made
  from a startup hook no longer re-runs or deadlocks startup.
- The index page takes one snapshot of ds.databases: a database removed,
  renamed or closed mid-request, or whose file was deleted, no longer turns
  the page into a 500. Database.size is 0 for a deleted file.

The scan-coalescing helpers move to datasette/utils/inflight.py.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwkLo2rJWidpkDVT3HkvNv
2026-10-04 09:07:48 +00:00
.github Deploy canned queries to latest.datasette.io again with workaround for #2916 2026-09-15 12:12:22 -07:00
datasette Torture harness, and the fixes it found 2026-10-04 09:07:48 +00:00
demos Fixed an unnecessary f-string 2024-02-04 10:15:21 -08:00
docs Torture harness, and the fixes it found 2026-10-04 09:07:48 +00:00
tests Torture harness, and the fixes it found 2026-10-04 09:07:48 +00:00
.coveragerc Configure code coverage, refs #841, #843 2020-06-13 13:48:23 -07:00
.dockerignore Build Dockerfile with SpatiaLite 5, refs #1249 2021-03-26 21:27:40 -07:00
.git-blame-ignore-revs Ignore Black commits in git blame, refs #1716 2022-04-22 14:58:46 -07:00
.gitattributes New explicit versioning mechanism 2020-10-28 20:38:15 -07:00
.gitignore Ignore ignored/ directory 2026-06-25 21:20:29 -07:00
.isort.cfg Used isort to re-order my imports 2018-05-14 00:04:23 -03:00
.prettierrc .prettierrc, refs #1166 2020-12-31 13:25:44 -08:00
.readthedocs.yaml dependency-groups and uv (#2611) 2025-12-11 17:32:58 -08:00
CODE_OF_CONDUCT.md Add code of conduct again 2022-03-15 08:38:42 -07:00
codecov.yml codecov should not be blocking 2020-07-02 21:29:32 -07:00
Dockerfile Fix Docker release builds on main with Bookworm base image 2026-09-10 18:52:19 -07:00
Justfile Screenshots for reusable modal dialogs docs, plus just shots (#2958) 2026-09-24 15:06:57 -07:00
LICENSE Initial commit 2017-10-22 17:39:03 -07:00
MANIFEST.in Include LICENSE in sdist (#1043) 2020-10-23 13:54:34 -07:00
package-lock.json Bump rollup from 3.29.5 to 3.30.0 (#2651) 2026-03-30 10:54:48 -07:00
package.json Bump rollup from 3.29.5 to 3.30.0 (#2651) 2026-03-30 10:54:48 -07:00
pyproject.toml Screenshots for reusable modal dialogs docs, plus just shots (#2958) 2026-09-24 15:06:57 -07:00
pytest.ini pytest skip tests in ignored/ folder 2026-09-16 16:22:48 -07:00
README.md README: minimum Python is 3.10, not 3.8 (#2878) 2026-09-15 12:38:41 -07:00
ruff.toml Upgrade to ruff>=0.16.0 (#2857) 2026-07-25 15:47:08 -07:00
setup.cfg Switch to ruff and fix all lint errors, refs #2630 2026-01-23 20:43:16 -08:00
test-in-pyodide-with-shot-scraper.sh Test against pyodide/v314.0.0 2026-06-22 10:11:56 -07:00

Datasette

PyPI Changelog Python 3.x Tests Documentation Status License docker: datasette discord

An open source multi-tool for exploring and publishing data

Datasette is a tool for exploring and publishing data. It helps people take data of any shape or size and publish that as an interactive, explorable website and accompanying API.

Datasette is aimed at data journalists, museum curators, archivists, local governments, scientists, researchers and anyone else who has data that they wish to share with the world.

Explore a demo, watch a video about the project or try it out on GitHub Codespaces.

Want to stay up-to-date with the project? Subscribe to the Datasette newsletter for tips, tricks and news on what's new in the Datasette ecosystem.

Installation

If you are on a Mac, Homebrew is the easiest way to install Datasette:

brew install datasette

You can also install it using pip or pipx:

pip install datasette

Datasette requires Python 3.10 or higher. We also have detailed installation instructions covering other options such as Docker.

Basic usage

datasette serve path/to/database.db

This will start a web server on port 8001 - visit http://localhost:8001/ to access the web interface.

serve is the default subcommand, you can omit it if you like.

Use Chrome on OS X? You can run datasette against your browser history like so:

 datasette ~/Library/Application\ Support/Google/Chrome/Default/History --nolock

Now visiting http://localhost:8001/History/downloads will show you a web interface to browse your downloads data:

Downloads table rendered by datasette

metadata.json

If you want to include licensing and source information in the generated datasette website you can do so using a JSON file that looks something like this:

{
    "title": "Five Thirty Eight",
    "license": "CC Attribution 4.0 License",
    "license_url": "http://creativecommons.org/licenses/by/4.0/",
    "source": "fivethirtyeight/data on GitHub",
    "source_url": "https://github.com/fivethirtyeight/data"
}

Save this in metadata.json and run Datasette like so:

datasette serve fivethirtyeight.db -m metadata.json

The license and source information will be displayed on the index page and in the footer. They will also be included in the JSON produced by the API.

datasette publish

If you have Heroku or Google Cloud Run configured, Datasette can deploy one or more SQLite databases to the internet with a single command:

datasette publish heroku database.db

Or:

datasette publish cloudrun database.db

This will create a docker image containing both the datasette application and the specified SQLite database files. It will then deploy that image to Heroku or Cloud Run and give you a URL to access the resulting website and API.

See Publishing data in the documentation for more details.

Datasette Lite

Datasette Lite is Datasette packaged using WebAssembly so that it runs entirely in your browser, no Python web application server required. Read more about that in the Datasette Lite documentation.