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yordis
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Sep 9, 2026
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| |> Stream.filter(&PubSub.subscribed?(event_store, &1.stream_uuid)) | ||
| |> Stream.map(&read_events(&1, state)) |
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I would appreciate it if this were placed behind a feature flag since this affects the system level architecture, this is not a local decision.
A subscribe can appear between the filter and map, and I do not know who in the codebases I maintain understands the implications of this change.
I would rather continue letting the Subscription engine handle the optimizations you are trying to implement than use :eventstore.
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Every node currently reads and deserializes each event notification before discovering that the local PubSub registry has no recipient. In a cluster with subscribers concentrated on a few nodes, this multiplies database reads and decoding work across the other nodes.
Filter notification topics before reading storage, using the existing local Registry. Exact-stream and
$allnotifications are checked separately. Persistent subscriptions still register before catching up from their durable checkpoint; acknowledgement and checkpoint handling are unchanged.The regressions cover skipped reads, unrelated/exact/
$allsubscribers, selectors and mappers, unregistering, and persistent catch-up after a skipped notification. Both fail against the original publisher and pass with the filter.Validation on Elixir 1.16.1 / OTP 26.2.5.7 with an isolated PostgreSQL 12 server:
mix test.all: passes for the default, JSONB, text-identifier and migration configurations (407 tests and 2 doctests per configuration, with the suite's normal exclusions).mix format --check-formatted,mix compile --warnings-as-errors, andmix dialyzer: pass.