VIvira28·Sep 26, 2026
Author here: Adding some context. I led the Postgres platform team (2019-23) at Cloudflare and we were supporting 170+ growing product teams. One of the constant asks is schema migration review. We published a lot of best practices, added CI checks however, it was still hard to catch. Also, I tried to explain the internals of how the locking (rewrite) works, but I realized most of the devs just want the answer - Is it safe or not safe to run?
Not sure if it rings a bell, the name is a reference to the Silicon Valley Jian Yang's hot dog or not hot dog app.
Also, I understand the decision of safe vs not-safe depends heavily on data/histogram and edge cases, but still quite a lot of low-hanging issues can be easily caught with a deterministic rule engine. So I ported pg_savior[1] and used sql parser from libpg-query-node[2] which compiles as
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WASM, so it entirely runs on the browser. No telemetry, no login. Source attached [3]
[1] https://github.com/viggy28/pg_savior
[2] https://github.com/constructive-io/libpg-query-node
[3] https://github.com/viggy28/safe-not-safe