Delta Contribution Review Plan

[schenksj]

Hey folks,

I’m hoping we can begin the review process for the Delta contribution. I’ve put together a proposal for breaking the work into approximately nine smaller, more manageable PRs, outlined in #4366:

#4366

I’d love to get the process underway soon, as keeping the tracking branch current and repeatedly resolving merge conflicts is becoming increasingly time-consuming.

I very much appreciate all the guidance and feedback you’ve provided so far.

Thanks,
Scott

Tagging those who have previously been involved: @andygrove, @mbutrovich, and @parthchandra

[schenksj]

Quick update — rather than keep waiting on the tracking branch, I went ahead and started landing the split.

Part 1 is open upstream as #4700 (core SPI for contrib leaf scans, CometScanWithPlanData) — it's core-only and inert on default builds. Parts 2–9 are split out and staged as a stacked review-draft chain on my fork (each part builds on the previous); they're ready to open here in dependency order as each base merges to main. Every part is carved, fully verified, and reviewed clean.

Part	What	PR
1	Core SPI for contrib leaf scans (CometScanWithPlanData) — core-only, inert on default builds	#4700
2	Build gate + inert Delta wiring (Maven profile, Cargo feature, proto, DeltaIntegration bridge)	schenksj#4
3a	Rust: driver-side planning (log replay, predicate pushdown, JNI)	schenksj#5
3b	Rust: executor-side read path (kernel read + deletion vectors)	schenksj#6
4a	Scala: claim/decline + scan marker	schenksj#7
4b	Scala: serde + native exec — end-to-end native reads	schenksj#8
5	Change Data Feed native reads	schenksj#9
6	Contrib test battery + CI workflow	schenksj#10
7	Delta own-suite regression harness	schenksj#11
8	Docs (design docs + user guide)	schenksj#12
9	FAILED_READ_FILE parity for Delta reads	schenksj#13

Full tracking (sizes, dependencies, status) is in the #4366 description. A review of #4700 would get the chain moving — keeping the tracking branch current is the time sink I mentioned.

Thanks again for all the guidance. @andygrove @mbutrovich @parthchandra