An open source multi-tool for exploring and publishing data https://datasette.io
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Alex Garcia 582d79a148 Propagate otel context across the thread boundaries
Spans created on a worker thread resolve their parent from that thread's
ambient context, so without this every span produced below Database came
back as an unparented root, disconnected from the request that caused it.
Carrying the caller's context across each boundary is also what makes the
thread-pool wait visible: db.query covers the full round trip, the new
db.query.execute covers only the work inside the worker, and the gap
between them is the queueing the old tracer folds invisibly into one
number.

- execute_fn()'s executor.submit() and execute_isolated_fn()'s
  run_in_executor() (immutable databases) now run the callable inside a
  contextvars.copy_context(). A *fresh* copy per submit is required:
  concurrently entering one shared Context raises "RuntimeError: cannot
  enter context ... already entered".
- WriteTask carries the otel Context captured on the event loop at enqueue
  time plus an enqueued_at_ns timestamp (both need __slots__ entries, or
  they fail with AttributeError at runtime). _execute_writes attaches that
  context right after the _SHUTDOWN check and detaches it in a finally
  spanning all three execution branches - the write thread is persistent
  and shared, so a leaked token would grow its context stack for every
  write processed afterwards, and a wrong-token detach only logs rather
  than raising.
- New spans: db.query.execute (read worker thread), db.write.queue_wait
  (explicit start/end timestamps, so its duration is the real enqueue ->
  dequeue wait rather than the microseconds spent building the span) and
  db.write.execute (skipped in the conn_exception branch, where fn never
  runs). db.query.execute honours log_sql_errors for the same reason
  db.query does: facet suggestion probes with log_sql_errors=False and
  would otherwise paint two red spans per text column on every table page.
- The write-thread warm-up prepare_connection is left as a documented
  orphan root - no caller context exists that early.

Tests assert actual parent/child span-id relationships in a shared trace,
not just that spans exist, since an unparented root looks identical to a
correct span if you only check presence.

Note that copy_context() copies every ContextVar, not just OTel's, so
Datasette's own context vars (_skip_permission_checks,
_permission_check_cache, _in_datasette_client) now flow into worker
threads where they previously did not.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-01 16:24:35 -07:00
.github check-latest: true, add 3.15 to test matrix, to test RCs (#2895) 2026-09-01 13:37:15 -07:00
datasette Propagate otel context across the thread boundaries 2026-09-01 16:24:35 -07:00
demos Fixed an unnecessary f-string 2024-02-04 10:15:21 -08:00
docs Release 1.0a38 2026-08-06 11:20:25 -07:00
tests Propagate otel context across the thread boundaries 2026-09-01 16:24:35 -07:00
.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 Upgrade Docker images to Python 3.11, closes #1853 2022-10-25 12:04:53 -07:00
Justfile Add Prettier check to lint recipe (#2821) 2026-07-03 09:50:35 -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 Add opentelemetry-api dependency and datasette/telemetry.py scaffolding 2026-09-01 16:24:15 -07:00
pytest.ini Initial Playwright setup plus first test 2026-06-14 16:39:55 -07:00
README.md Replace Glitch with Codespaces, closes #2488 2025-05-28 19:17:22 -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 3.8 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.