fix(performance): exclude db.cursor spans from N+1 DB detection#118031
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ericapisani wants to merge 3 commits into
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fix(performance): exclude db.cursor spans from N+1 DB detection#118031ericapisani wants to merge 3 commits into
ericapisani wants to merge 3 commits into
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Cursor iteration (e.g. asyncpg BaseCursor._exec on each cursor.fetch()) produces N spans with the original SQL as their description. These are sequential FETCH calls draining a pre-existing server-side cursor, not N independently issued queries — equivalent to how db.redis and db.connection are already excluded. Paired SDK change: sentry-python asyncpg integration will tag cursor fetch spans with op='db.cursor.fetch' instead of the generic 'db' op. Co-Authored-By: sentry-junior[bot] <264270552+sentry-junior[bot]@users.noreply.github.com>
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Summary
Cursor iteration in asyncpg (and other DB drivers that support server-side cursors) produces N spans that share the original SQL as their description. Each
cursor.fetch()andcursor.__anext__calls trigger aBaseCursor._execinvocation, which the SDK wraps as adbspan — so the detector sees a source span followed by N identical repeating spans and fires a false-positive N+1 alert.These are sequential calls draining a pre-existing server-side cursor result set, not N independently issued queries. They should be excluded from N+1 detection the same way
db.redisanddb.connectionalready are.Changes
n_plus_one_db_span_detector.py: addnot op.startswith("db.cursor")to_is_db_op, consistent with existingdb.redisanddb.connectionexclusions.test_n_plus_one_db_span_detector.py: adds tests for the 2 new operation names introduced that start withdb.cursorfollowing the pattern of thepg-pool.connectand cached-query tests.Paired SDK change
The sentry-python asyncpg integration needs to tag cursor fetch spans with
op='db.cursor.fetch'instead of the generic'db'op. That change will be tracked in getsentry/sentry-python.See getsentry/sentry-python#6609
Context
cursor-n+1-reproin ep-starlette project on sentry-sdks orgView Session in Sentry