Files
fbe7b96138 fix(eventstore): prevent projections from skipping events (#12703)
<!-- CURSOR_AGENT_PR_BODY_BEGIN -->
# Which Problems Are Solved

Handler/v2 projections (`users14` and every other event projection) can
overlook committed events under load:

- `eventstore.commands_to_events` stamped `position` with `NOW()`
(transaction start). A slow create TX could commit after a faster TX
that started later, so the projector stored a later position and never
saw the earlier one.
- Resume used `OFFSET` on a **filtered** row count. That could skip
`in_tx_order = 1` at the next position (for example `user.human.added`).
- Two transactions in the same microsecond both start at `in_tx_order =
1`. A cursor of `in_tx_order > last` alone would drop the other TX’s
first event.

This does not repair rows that are already missing from projections.

# How the Problems Are Solved

- Setup step 77 replaces `eventstore.commands_to_events` so `created_at
= statement_timestamp()` and `position = EXTRACT(EPOCH FROM
clock_timestamp())` at INSERT time. Initialise `08_events_table.sql`
matches that for new databases. The function is `VOLATILE` to match
`clock_timestamp()`.
- The projector still drains in-flight writers with `pg_advisory_lock` /
`pg_advisory_unlock` in one statement, then caps with `position <=
EXTRACT(EPOCH FROM now())` (projector TX start). The exclusive lock is
**not** held across the event `SELECT`. The cap must stay `now()`, not
`clock_timestamp()`, or later inserts become a high-water mark.
- Resume is a lexicographic `EventSortKey` on `(position, in_tx_order,
instance_id, aggregate_type, aggregate_id, sequence)` via
`AfterEventSortKey`. SQL `OFFSET` is no longer used for projection
catch-up.
- Handler and FieldHandler persist the last event’s `in_tx_order` in
`current_states.filter_offset` (existing column, new meaning). Step 77
backfills matching rows from `events2`; unmatched rows keep their
previous value.

# Additional Changes

- `eventstore.Event` exposes `InTxOrder() uint32` (BaseEvent, repository
Event, v3 event, v1 models).
- v3 push SELECT/RETURNING now includes `in_tx_order` so newly written
events carry a real ordinal.
- `WithMinPosition` stays an inclusive `PositionAtLeast` floor and does
not smash the sort-key cursor.
- `SearchQuery.PositionAfter(decimal)` is unchanged (used by
access-token lookup). Do not confuse it with
`SearchQueryBuilder.AfterEventSortKey`.
- `commands_to_events` in setup 77 and initialise 08 is `VOLATILE
PARALLEL SAFE`. Shipped 40/64/70 stay `STABLE` because they still stamp
with `NOW()`.
- Drop unused `last_owner TEXT` DECLARE from setup 77 and initialise
`08_events_table.sql` (`i INTEGER` remains for the enforce-owner loop).
Shipped 40/64/70 keep the leftover.
- This PR’s migration is numbered 77 because `main` already has setup 76
(`76_users14_login_equality_indexes`). First-loop order is s70, then
main’s 76, then this 77.

# Additional Context

**Reviewer map**

| Start here | Why |
| --- | --- |
| `cmd/setup/77.sql` + `cmd/setup/77.go` | Position stamp + atomic
function replace/backfill after shipped `s70` and main’s s76 |
| `internal/eventstore/event_sort_key.go` + `search_query.go` |
Canonical cursor and `AfterEventSortKey` |
| `internal/eventstore/handler/v2/{state.go,handler.go}` |
Persist/resume cursor; `eventQuery` |
| `internal/eventstore/repository/sql/{query.go,postgres.go}` | Tuple
`>` filter, 6-column `ORDER BY`, await cap |
| `internal/eventstore/v3/push.go` / `push.sql` | Scan `in_tx_order` on
write |

Mechanical / low-risk: handler and query test fixtures, Event interface
stubs (`event_base.go`, repository Event, mocks, v1 models).

**Do not look for** a `70.sql` change — shipped migrations stay as on
`main`. Setup 40/64 still use `NOW()`; step 77 overwrites the function
afterward. Fresh `FirstInstance` (runs before `s70`) can still stamp
`NOW()` until 77; runtime pushes after 77 use `clock_timestamp()`.
Main’s `cmd/setup/76.go` is the users14 login-equality indexes, not this
stamp.

**Rollout**

1. Run setup so 77 replaces `commands_to_events` and backfills
`filter_offset`.
2. Restart ZITADEL so projectors load the new resume path.
3. Existing missing `users14` rows are not repaired by this PR.

**Tests**

- `go test ./internal/eventstore/... ./cmd/setup/`
- Sort-key SQL fixtures in `query_sort_key_test.go` (no `OFFSET`;
aggregate-id queries keep 6-column `ORDER BY`)
- `cmd/setup/77_test.go` asserts the embed has no unused `last_owner`
and still uses `clock_timestamp()` / `VOLATILE PARALLEL SAFE`

Related: #8509, #10480 (remove OFFSET), #10560 (advisory locks), #10710
(stable ORDER BY).
Out of scope: repairing already-missing projection rows, holding the
exclusive lock during SELECT, rewriting historical setup 40/64 SQL.
<!-- CURSOR_AGENT_PR_BODY_END -->

<div><a
href="https://cursor.com/agents/bc-3da6eb51-11d4-4a8a-8ba0-e190f116df05?cursor_ref=pr_footer&cursor_cta=open_in_web"><picture><source
media="(prefers-color-scheme: dark)"
srcset="https://cursor.com/assets/images/open-in-web-dark.png"><source
media="(prefers-color-scheme: light)"
srcset="https://cursor.com/assets/images/open-in-web-light.png"><img
alt="Open in Web" width="114" height="28"
src="https://cursor.com/assets/images/open-in-web-dark.png"></picture></a>&nbsp;<a
href="https://cursor.com/background-agent?bcId=bc-3da6eb51-11d4-4a8a-8ba0-e190f116df05&cursor_ref=pr_footer&cursor_cta=open_in_cursor"><picture><source
media="(prefers-color-scheme: dark)"
srcset="https://cursor.com/assets/images/open-in-cursor-dark.png"><source
media="(prefers-color-scheme: light)"
srcset="https://cursor.com/assets/images/open-in-cursor-light.png"><img
alt="Open in Cursor" width="131" height="28"
src="https://cursor.com/assets/images/open-in-cursor-dark.png"></picture></a>&nbsp;</div>

---------

Co-authored-by: Cursor Agent <[email protected]>
Co-authored-by: Silvan <[email protected]>
2026-09-09 11:08:50 +02:00

100 lines
3.2 KiB
PL/PgSQL

CREATE OR REPLACE FUNCTION eventstore.commands_to_events(commands eventstore.command2[])
RETURNS SETOF eventstore.events2
LANGUAGE 'plpgsql'
VOLATILE PARALLEL SAFE
ROWS 10
AS $$
DECLARE
_latest_events eventstore.latest_command[];
command eventstore.command2;
i INTEGER;
BEGIN
SELECT array_agg(res) INTO _latest_events
FROM (
SELECT
ROW(
c.instance_id,
c.aggregate_type,
c.aggregate_id,
COALESCE(e.owner, c.owner),
COALESCE(e.sequence, 0)
)::eventstore.latest_command AS res
FROM (
SELECT DISTINCT ON (c.instance_id, c.aggregate_type, c.aggregate_id)
c.instance_id,
c.aggregate_type,
c.aggregate_id,
c.owner,
c.ordinality
FROM (
SELECT *
FROM UNNEST(commands) WITH ORDINALITY AS c
) AS c
ORDER BY
c.instance_id,
c.aggregate_type,
c.aggregate_id,
c.ordinality
) AS c
LEFT JOIN LATERAL (
SELECT
e.owner,
e.sequence
FROM eventstore.events2 AS e
WHERE e.instance_id = c.instance_id
AND e.aggregate_type = c.aggregate_type
AND e.aggregate_id = c.aggregate_id
ORDER BY e.sequence DESC
LIMIT 1
) AS e ON TRUE
) AS latest;
FOR command IN SELECT * FROM UNNEST(commands) LOOP
IF NOT command.enforce_owner THEN
SELECT owner INTO command.owner
FROM UNNEST(_latest_events) AS e
WHERE e.instance_id = command.instance_id
AND e.aggregate_type = command.aggregate_type
AND e.aggregate_id = command.aggregate_id;
ELSE
FOR i IN 1..array_length(_latest_events, 1) LOOP
IF _latest_events[i].instance_id = command.instance_id
AND _latest_events[i].aggregate_type = command.aggregate_type
AND _latest_events[i].aggregate_id = command.aggregate_id
THEN
_latest_events[i].owner := command.owner;
EXIT;
END IF;
END LOOP;
END IF;
END LOOP;
RETURN QUERY SELECT
c.instance_id
, c.aggregate_type
, c.aggregate_id
, c.command_type AS event_type
, COALESCE(e.sequence, 0) + ROW_NUMBER() OVER (PARTITION BY c.instance_id, c.aggregate_type, c.aggregate_id ORDER BY c.ordinality) AS sequence
, c.revision
, statement_timestamp() AS created_at
, c.payload
, c.creator
, CASE WHEN c.enforce_owner
THEN c.owner
ELSE COALESCE(e.owner, c.owner)
END AS owner
, EXTRACT(EPOCH FROM clock_timestamp()) AS position
, c.ordinality::%s AS in_tx_order
FROM UNNEST(commands) WITH ORDINALITY AS c
LEFT JOIN unnest(_latest_events) AS e
ON c.instance_id = e.instance_id
AND c.aggregate_type = e.aggregate_type
AND c.aggregate_id = e.aggregate_id
ORDER BY
in_tx_order;
END;
$$;