PgQue v0.3.0-alpha.1

Prerelease — for testing only. This alpha ships the new partition-keys and
producer-idempotency work for early feedback. Install it from
devel/sql/pgque.sql at this tag. The stable install under sql/ remains
0.2.0 and is unchanged; use that for anything real.

This is an SQL-only alpha. The client libraries (gem / PyPI / npm / Go module)
are not being versioned or published in this stamp — client releases will
follow once the partition-keys surface stabilizes.

Highlights

Partition keys — ordered per-key processing (#295)

Consume a queue with strict per-key ordering while still processing different
keys in parallel. Events are distributed across a fixed set of slots; each
slot is consumed by one worker at a time, and ordering is preserved within a
slot. Coordination uses batch-granularity leases rather than advisory
locks, so it is safe behind a transaction pooler (e.g. PgBouncer in
transaction mode) and needs no session-level state.

There are no client-library helpers yet — drive it with the raw SQL described
in blueprints/partition-keys/SPEC.md (see §15). User-facing docs under
docs/ are still pending; the SPEC is the reference for now.

Producer idempotency — pgque.send_idem() (#295)

Deduplicate on the producer side: pgque.send_idem() claims an idempotency
key and appends the event atomically, so a retried producer call does not
enqueue a duplicate event.

New: Ruby client (#234)

A pgque Ruby gem joins the client lineup. (Not published to RubyGems in this
alpha — see the SQL-only note above.)

Fixes rolled in

• get_queue_info is reader-callable — consumers can read queue metadata
  without writer/admin grants (#267).
• dlq_replay concurrent double-replay guarded — two workers can no longer
  replay the same DLQ event twice (#287).
• Uninstall hardening — scheduler jobs are torn down, and the uninstall
  scripts abort loudly instead of silently swallowing errors (#290).
• transform.sh build guards — the build fails loud on integrity
  regressions instead of emitting a subtly wrong install file (#292).
• Go client — NULL type/payload columns scan correctly, and ack failures
  back off instead of hot-looping (#285, #284).
• TypeScript client — ack/nack now back off on failure; benchmark harness
  hardened (#289).
• Python client — consumer drains cleanly and survives per-event errors
  without aborting the loop (#291).
• Experimental SQL — throughput division-by-zero and negative
  max_retries fixed, with CI coverage added (#288).

Continuous integration

PostgreSQL 19 beta 1 is now part of the continuously tested server matrix
(PG 14–19beta1).

Breaking change (Python client)

Event.extra has been removed. It never functioned — data passed via
extra was silently dropped. Passing extra= now raises TypeError at the
call site instead of failing silently. Update callers to stop passing it.

Known limitations — partition-keys alpha

Partition keys are alpha. Read blueprints/partition-keys/SPEC.md before
relying on any of this, and watch pgque.partition_slot_status.

• No sticky-worker takeover (M=N). When a sticky worker stops, its freed
  slot is not automatically picked up by another worker.
• Stale subscriptions pin rotation silently. A subscribed-but-idle slot
  holds back tick rotation with no error. Monitor
  pgque.partition_slot_status.
• i_max caps a slot's batch slice. On the partitioned path, events beyond
  i_max in a batch are skipped for that slot and picked up on the next batch.
• Every subscribed slot must be polled. If any subscribed slot is never
  consumed, rotation pins. Poll all subscribed slots.
• Partial unsubscribe_slot orphans its key-class. Unsubscribing only some
  slots of a key-class can leave that class orphaned.
• Non-superuser-installer variant is not yet security-tested.
• No client-library helpers yet. Use the raw SQL in the SPEC (§15).
• User-facing docs pending. docs/ coverage is not in this alpha.

Install

begin;
\i devel/sql/pgque.sql
commit;

Requires PostgreSQL 14+ and a periodic ticker. See devel/sql/README.md for
ticker setup and role grants.