RFC 0001: pgmold owns expand/contract zero-downtime migrations#331
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RFC 0001: pgmold owns expand/contract zero-downtime migrations#331fmguerreiro wants to merge 3 commits into
fmguerreiro wants to merge 3 commits into
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evaluates whether pgmold should subsume pgroll's zero-downtime expand/contract responsibility. carries four options: fix the pipeline seams (A), rebuild pgroll stateless (B), rebuild pgroll stateful (C), and pgmold-plans-pgroll-executes (E). recommends A now, E as the long-term target gated on a pgroll op-vocab coverage spike. includes the L0-L8 test matrix as the risk section.
pins how pgmold and pgroll are used together under E: the thin pgroll-awareness stance (file-format + object-ignore, no state coupling), the loose-vs-tight orchestration fork, the pipeline deploy sequence, the v5.4.0 worked example showing the failure is impossible by construction, and the loud coverage fallback.
spike run locally and closed. result: not a pgroll-coverage question. pgmold cannot represent a rename (no Rename op; name-keyed diff); proven by execution it emits destructive drop+add that fails on a populated table. pgroll v0.16 vocab is rich, not the bottleneck. recommendation reframed: ship A now (pipeline reorder + ownership boundary), add a rename directive as an independent pgmold-correctness item (Beads pgmold-3po5), defer E until that ships and only if the managed coupling tax proves painful. spike Beads pgmold-e5bj closed.
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design doc: should pgmold subsume pgroll's expand/contract responsibility.
doc: docs/rfc/0001-pgmold-owns-expand-contract.md
status Draft. needs stakeholder review before Proposed.