- Remove the registry's unused prefix=True slot, its span_for() branch,
its doc-rendering case and its test - nothing in the stack sets it.
- Stop promising a "later phase" query-duration metric dimension in the
db.operation.name description; the cardinality rationale stands alone.
- Replace baked-in benchmark numbers in the telemetry module docstring
with the docs' own phrasing (below run-to-run variation).
- Compact the duplicated copy_context() and enqueue-site comments in
database.py to pointers at their canonical tellings.
- Make the "catch people out" gotchas skimmable as a bullet list and
give the changelog's "nothing is removed" line a clear antecedent.
- Add a test that a result cut short by max_returned_rows records
datasette.truncated=True - previously only ever asserted False.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012U7coQfVu8nK2R4q2mCULA
The span and attribute names were string literals spread across four call
sites in database.py and one in app.py, with a hand-written reference page
that would have been true only on the day it was written. That drift is not
hypothetical: an earlier iteration of this work carried a README asserting
parameter values were never recorded for two branches after that had stopped
being true.
datasette/telemetry_registry.py now holds each name once, with its
documentation. Attribute and SpanName subclass str, so a registry entry *is*
the string OpenTelemetry wants - no wrapper API over the OTel calls, no
parallel structure to keep in step, and a typo becomes an ImportError rather
than a silently misnamed attribute. docs/internals.rst renders the span
reference from it via cog, and `cog --check docs/*.rst` already runs in CI,
so the reference cannot drift from the definitions.
Nothing changes on the wire: the emitted span names and attribute keys are
byte-identical before and after, verified by diffing a dump of both.
tests/test_telemetry_registry.py exercises a real workload and compares it
against the registry in both directions - emitted-but-unregistered catches
instrumentation added without documentation, registered-but-never-emitted
catches documentation that has outlived its code. Because the call sites now
take their names from the registry, neither direction can catch a rename:
move DB_NAMESPACE to "db.namespace2" and code and registry still agree while
every dashboard breaks. So the literal names are also written out in the test
and asserted against the registry and against the wire separately. That pair
is the only comparison in the file not derived from the registry itself.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
