Glean Dictionary + DuckDB
August 23, 2026
While working on Writing the Docs: 2026 Edition, I experimented a bit with updating the Glean Dictionary to incorporate some of the ideas in the essay, in particular those around reference documentation.
As a sort of demonstration that documentation about an application can be treated as a data product in and of itself, I hacked up a quick ETL pipeline to dump the JSON output of the Glean Dictionary into a DuckDB database that can be queried standalone.
Since the Glean Dictionary is just a static Netlify site, the DuckDB database can simply be published alongside as a standard file. This allows you to do fun things from the DuckDB console like:
memory D ATTACH 'https://glean-dictionary-DuckDB.netlify.app/data/glean_dictionary.DuckDB' AS glean_dictionary (READ_ONLY);
memory D SELECT type, count(*) AS metrics
FROM glean_dictionary.metrics
GROUP BY type
ORDER BY metrics DESC;
┌─────────────────────────────┬─────────┐
│ type │ metrics │
│ varchar │ int64 │
├─────────────────────────────┼─────────┤
│ counter │ 20057 │
│ event │ 7256 │
│ string │ 3545 │
│ labeled_counter │ 3275 │
│ timing_distribution │ 2481 │
│ custom_distribution │ 2169 │
│ quantity │ 1406 │
│ boolean │ 1078 │
│ text │ 588 │
│ labeled_timing_distribution │ 569 │
│ datetime │ 404 │
│ memory_distribution │ 389 │
│ object │ 369 │
│ labeled_custom_distribution │ 340 │
│ rate │ 215 │
│ dual_labeled_counter │ 210 │
│ string_list │ 204 │
│ uuid │ 181 │
│ timespan │ 149 │
│ labeled_boolean │ 118 │
│ labeled_string │ 84 │
│ labeled_memory_distribution │ 66 │
│ labeled_quantity │ 42 │
│ url │ 26 │
└─────────────────────────────┴─────────┘
24 rows 2 columns
From there, you could either build an interface like the Glean Dictionary itself (much easier to do from a database than the somewhat harebrained dataclass soup I originally came up with) or any number of other data products or analyses. Here's an example marimo notebook that tracks the metrics added to each product over time:
As you can see, the number of metrics did a big jump in 2024 (I imagine they finally moved Firefox Desktop over to Glean) with slower and steadier growth since.