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Eveandmultica-agent
faf03e8364
Addresses the second review round on MUL-5999.
1. Bounded scan, not just bounded result. The page query was
`owner = $1 ORDER BY id LIMIT n` against indexes that cannot produce id
order, so the executor had to read the owner's whole task set before
applying LIMIT — quadratic in pages for a busy owner, which is the case
this issue is about. Measured on a 550k-row probe: the old shape spent
11,630 buffers per page (planner chose a full pkey index scan; on other
statistics it chose an explicit Sort), the keyset shape spends ~2,000
and a later page costs the same as the first.
Pages are now `owner = $1 AND id > $cursor ORDER BY id LIMIT n` against
composite indexes: 273 becomes (runtime_id, id), 278 adds (agent_id, id),
279 adds (issue_id, id) and 280 drops the single-column issue_id index it
supersedes so the hot table does not carry both.
2. Owner enumeration is bounded too. The three LockWorkspaceTaskOwner*
statements no longer return ids at all — they are a set-based write fence
and now cost the API process nothing. Owners are walked separately in
keyset pages of 500 (281-283 add the (workspace_id, id) indexes those
pages need), so a workspace with a huge agent or issue set never has its
whole owner list held in memory.
The keyset column is id rather than a natural key on purpose: a cursor
column must be immutable, and renaming an owner mid-teardown would
otherwise let it sort behind the cursor and escape the sweep.
3. The fence is no longer the only guarantee. Blocking a concurrent enqueue
still relies on an INSERT taking FOR KEY SHARE on the owner rows it
references, which is a property of the legacy FKs rather than a protocol
every enqueue path opts into. Two things now backstop it:
- every owner is re-swept until a pass finds nothing, and teardown fails
closed (rolling the whole transaction back) if tasks keep arriving,
instead of committing a partially cleaned tenant;
- a schema-contract test asserts the three owner FKs still exist, so a
migration that removes them turns the missing fence into a red build
rather than a silent hole.
An explicit deleting-state protocol shared with all seven enqueue paths
remains the right long-term fix and is out of scope here.
End-to-end teardown, real handler, identical synthetic data, main vs this
branch (1.2M-row agent_task_queue, 200k task_token, 300k task_usage):
small workspace, 5k tasks: 29,247 ms -> 1,013 ms (4.38M -> 0.27M blocks)
busy workspace, 60k tasks: 243,863 ms -> 1,724 ms (5.76M -> 2.23M blocks)
Refs MUL-5999
Co-authored-by: multica-agent <[email protected]>