fix(monitor): DB-accurate max_age metrics #89
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smudge
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ebrooksbetter,
effron,
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okasten
smudge
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Feb 5, 2026
smudge
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Feb 5, 2026
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Probably best to view this diff with ?w=1 in the URL (to skip whitespace-only changes).
smudge
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Feb 5, 2026
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| match do |block| | ||
| @expected = { event_name: expected_event_name, payload: expected_payload, value: expected_value } | ||
| if @approximately && current_adapter != 'postgresql' |
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On postgres, we can fully align Timecop with the transaction's NOW() -- on other DB engines, we need to account for slight variance in query time.
smudge
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Feb 5, 2026
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| db_adapter = ENV["ADAPTER"] | ||
| gemfile = ENV["BUNDLE_GEMFILE"] | ||
| db_adapter ||= gemfile && gemfile[%r{gemfiles/(.*?)/}] && $1 # rubocop:disable Style/PerlBackrefs |
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I removed this line entirely as we no longer rely on adapter-specific gemfiles.
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This ensures that max_lock_age and max_age are not artificially inflated by slower query times. Previously, if the query took N seconds to perform, N seconds would be artificially added to `max_age` and `max_lock_age`. Now, we rely on the DB's own reported UTC time at the time of the query. In PostgreSQL, this will correspond to the start of the transaction, and in other DB engines this will correspond to the DB's clock time as the query executes, so there is still some small variance but it is much smaller than before. /no-platform
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This ensures that
max_lock_ageandmax_ageare not artificially inflated by slower query times. Previously, if the query took N seconds to perform, N seconds would be artificially added tomax_ageandmax_lock_age. (Typically this is not a problem for sub-second queries on small-medium tables, but on large tables this can trigger occasional alert thresholds on sensitive/high-priority queues.)With this PR, we rely on the DB's own reported UTC time at the time of the query to compute timestamp ages as of said query.
In PostgreSQL, the DB's "now" will correspond to the start of the transaction (as should the state of the rows it returns), and in other DB engines it will correspond to a clock time during execution, so there is still room for variance but it is much smaller than before.
/no-platform