fix(modeling): fix generic delta errors and s3 fnf errors from empty queryable tables

[andrewjmcgehee]

Problem

we get generic delta errors from renamed (lowercased) columns names; we also get file not found errors in s3

Changes

avoid the delta data fusion write path by using always using mode overwrite. we delete the s3 folder anyway.
to be clear, this is a temporary fix. if we want to support incremental matviews in the future we will HAVE to
find a better way around this. probably some setting somewhere in deltalake. but if we are moving to iceberg
/ ducklake and away from delta format anyway this might not be worth digging into.

How did you test this code?

tests

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Publish to changelog?

no

Docs update

no

🤖 Agent context

gg stack

• fix(modeling): fix generic delta errors and s3 fnf errors from empty queryable tables #60688 andrew/delta-fnf-errors 👈 this PR

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
posthog/temporal/data_modeling/activities/materialize_view.py:579-588
**Drain loop not cancellation-safe under activity cancellation**

If Temporal cancels the activity while the drain loop is sleeping, `await asyncio.sleep(0.05)` raises `CancelledError`, which propagates immediately out of the `finally` block — `await producer_task` is never reached. If the producer is simultaneously blocked on `await asyncio.to_thread(batch_queue.put, SENTINEL)` (queue still full because nothing drained it), the thread pool thread holding that `put` is orphaned until the GC eventually drops the queue, and the producer task itself is left un-awaited. Wrapping the drain section in `try/except asyncio.CancelledError` (re-raising after awaiting the task) or guarding with `asyncio.shield(producer_task)` would close this gap.

_{Reviews (1): Last reviewed commit: "fix delta generic errors and s3 fnf erro..." | Re-trigger Greptile}

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-06-01 02:43 UTC	Run
prod-us	✅ Deployed	2026-06-01 02:54 UTC	Run
prod-eu	✅ Deployed	2026-06-01 02:56 UTC	Run