{"id": "changelog:v0-28-register-output-renderer", "page": "changelog", "ref": "v0-28-register-output-renderer", "title": "register_output_renderer plugins", "content": "Russ Garrett implemented a new Datasette plugin hook called  register_output_renderer  ( #441 ) which allows plugins to create additional output renderers in addition to Datasette's default  .json  and  .csv . \n                 Russ's in-development  datasette-geo  plugin includes  an example  of this hook being used to output  .geojson  automatically converted from SpatiaLite.", "breadcrumbs": "[\"Changelog\", \"0.28 (2019-05-19)\"]", "references": "[{\"href\": \"https://github.com/simonw/datasette/pull/441\", \"label\": \"#441\"}, {\"href\": \"https://github.com/russss/datasette-geo\", \"label\": \"datasette-geo\"}, {\"href\": \"https://github.com/russss/datasette-geo/blob/d4cecc020848bbde91e9e17bf352f7c70bc3dccf/datasette_plugin_geo/geojson.py\", \"label\": \"an example\"}]"}
{"id": "changelog:v0-28-databases-that-change", "page": "changelog", "ref": "v0-28-databases-that-change", "title": "Supporting databases that change", "content": "From the beginning of the project, Datasette has been designed with read-only databases in mind. If a database is guaranteed not to change it opens up all kinds of interesting opportunities - from taking advantage of SQLite immutable mode and HTTP caching to bundling static copies of the database directly in a Docker container.  The interesting ideas in Datasette  explores this idea in detail. \n                 As my goals for the project have developed, I realized that read-only databases are no longer the right default. SQLite actually supports concurrent access very well provided only one thread attempts to write to a database at a time, and I keep encountering sensible use-cases for running Datasette on top of a database that is processing inserts and updates. \n                 So, as-of version 0.28 Datasette no longer assumes that a database file will not change. It is now safe to point Datasette at a SQLite database which is being updated by another process. \n                 Making this change was a lot of work - see tracking tickets  #418 ,  #419  and  #420 . It required new thinking around how Datasette should calculate table counts (an expensive operation against a large, changing database) and also meant reconsidering the \"content hash\" URLs Datasette has used in the past to optimize the performance of HTTP caches. \n                 Datasette can still run against immutable files and gains numerous performance benefits from doing so, but this is no longer the default behaviour. Take a look at the new  Performance and caching  documentation section for details on how to make the most of Datasette against data that you know will be staying read-only and immutable.", "breadcrumbs": "[\"Changelog\", \"0.28 (2019-05-19)\"]", "references": "[{\"href\": \"https://simonwillison.net/2018/Oct/4/datasette-ideas/\", \"label\": \"The interesting ideas in Datasette\"}, {\"href\": \"https://github.com/simonw/datasette/issues/418\", \"label\": \"#418\"}, {\"href\": \"https://github.com/simonw/datasette/issues/419\", \"label\": \"#419\"}, {\"href\": \"https://github.com/simonw/datasette/issues/420\", \"label\": \"#420\"}]"}