Commit Message Style

commit-message-style

PostgreSQL has a strong, consistent commit-message house style. It is not "conventional commits" and it is not GitHub-flavored. Match it whenever the change is meant to plausibly land on master.

1. Anatomy

<imperative one-line summary, under ~64 chars>

<one or more paragraphs of prose, wrapped near 72–76 chars,
explaining the why and the what — not a diff recap>

Author: First Last <email@example.com>
Reviewed-by: First Last <email@example.com>
Reported-by: First Last <email@example.com>
Discussion: https://postgr.es/m/<message-id>
Backpatch-through: <branch>

The order is: subject, blank line, narrative paragraphs, blank line, trailer block. The trailer block always ends the message. [from-wiki: Commit_Message_Guidance — "Summary line / Blank line / Narrative (with paragraphs separated by blank lines) / Tags section"]

2. The title line

• Imperative mood: "Fix X", "Improve Y", "Add Z" — not "Fixes" or "Fixed".
• Capitalize the first word. No trailing period.
• Under ~64 characters when possible (email subject-line limit). [from-wiki: Commit_Message_Guidance — "Keep under 64 characters"]
• No prefix tag unless the change is scoped to a specific subsystem that has an established prefix in the log. Common observed prefixes: doc:, libpq:, psql:, pg_dump:, postgres_fdw:, pg_upgrade:, pgbench:, pg_basebackup:. Module name + colon, lowercase. [verified-by-code: git log --oneline -50 shows doc: Correct the timeline for OAuth's shutdown_cb (08127c641c0), libpq: Fix grease error message style (5ca41e4125e), postgres_fdw: Fix whitespace violation in connection.c (af23353a73d)]
• Do not use conventional-commits style: no feat:, fix:, chore:, refactor:. [verified-by-code: zero matches for ^feat: or ^chore: in git log --oneline -200.]

3. The body

• Wrap at 72–76 columns. Inspection of recent commits shows lines mostly ≤76. [verified-by-code: see body of db5ed03217b, 5fee7cab1b8, 89d243d5218 — all wrap in that range.]
• Paragraph form, not bullets. Bullets do appear occasionally (e.g. numbered repro scenarios) but the default is prose. [verified-by-code: 5fee7cab1b8 uses a numbered 1)–7) reproduction list, surrounded by prose paragraphs. Pure-bullet bodies are rare.]
• Explain why the change is needed and what approach was taken. Do not restate the diff line-by-line.
• When fixing a regression, name the introducing commit. Use 9-char SHA so the web UI hyperlinks it. [from-wiki: Committing_checklist — "it's a good idea to use the first 9 chars of the commit SHA. Fewer than 9 means there will be no hyperlink in the HTTP interface." verified-by-code: 7dc5bbcf220 body says "Introduced by 7dadd38cda9 (json format for COPY TO)."]

4. The trailer block

Format: Tag: Name <email> [(optional short context)], one tag per line, each starting at column 0. Repeat the tag for multiple people; do not comma-separate. [from-wiki: Commit_Message_Guidance]

Standard tags, in roughly the order you'll see them:

[from-wiki: Commit_Message_Guidance; all observed in recent log verified-by-code — see db5ed03217b (Author + 3x Reviewed-by + Discussion), b1901e2895e (Reported-by + 2x Analyzed-by + Discussion).]

Notes:

• Attribution is cut-and-paste from the email From: header, unaltered. Don't normalize names or emails. [from-wiki: Commit_Message_Guidance]
• If the committer is also the sole patch author, omit Author: entirely — don't write Author: <self>. Reported-by: / Reviewed-by: etc. still apply as usual. [verified-by-code: 08127c641c0 is committer-authored and has no Author: line.]
• Discussion: URL uses the postgr.es/m/... shortener, not the raw archives URL. Prefer https://; http:// also appears occasionally and is accepted, but https:// dominates recent log. [verified-by-code: in git log -100 Discussion lines, 93 are https://postgr.es/m/ vs 2 http://postgr.es/m/.]
• Backpatch-through: value is the oldest branch that gets the fix, expressed as a major-version number: 18, 15, 14. Good: Backpatch-through: 16. Bad: Backpatch-through: 16-18, Backpatch-through: REL_16_STABLE, Backpatch from master. (The wiki notes that range and only forms are technically allowed, but recent practice in the log is overwhelmingly the bare-oldest form.) [verified-by-code: 08127c641c0 has Backpatch-through: 18; 89d243d5218 has Backpatch-through: 14; recent log (git log -200) shows the bare-version form on all 63 observed instances. from-wiki: Commit_Message_Guidance — "use oldest branch version (e.g., '15'), range format (e.g., '13-15'), or 'only' for single branches".]
• For master-only commits, omit Backpatch-through: entirely. [from-wiki: Commit_Message_Guidance]

5. What is NOT in PG commit messages

Verified by git log --grep over recent history; absence is real:

• No Co-Authored-By: (capital A B Y) — that's the GitHub / Claude Code convention. PG uses Co-authored-by: (lowercase a / b). [verified-by-code: search of recent log shows lowercase form only.] Do not add the Co-Authored-By: Claude trailer to PG commits.
• No conventional-commits prefix. No feat:, fix:, chore:, refactor:, BREAKING CHANGE:. [verified-by-code: 0 matches in recent log.]
• No emoji. [verified-by-code: scan of git log -50 --format=%s%n%b — none present.]
• No ticket numbers / issue refs from external trackers. PG uses the mailing list and its Bug: #NNNN form for community bug numbers, not GitHub issue links. [from-wiki + verified-by-code.]
• No "Signed-off-by:". PG is not a DCO project. [verified-by-code: 0 occurrences in recent log.]
• No diff recap bullets ("- changed foo\n- added bar"). The body explains intent. [verified-by-code: see examples in §6.]

6. Three verbatim examples

Example A — straightforward fix with reviewer credit

Avoid leaking system path from pg_available_extensions

The documentation says that when extension_control_path is set to an
empty string, the default '$system' path is still assumed.  However,
get_extension_control_directories() added the system extension directory
with a NULL macro in that case.  As a result, pg_available_extensions
could expose the expanded system directory path instead of reporting
'$system' as the location.

Record the implicitly-added system directory with the '$system' macro, so
pg_available_extensions reports the documented symbolic location and does
not leak the actual system path.

Update the extension_control_path TAP test to check the reported location
directly.

Author: Chao Li <lic@highgo.com>
Reviewed-by: Lu Feng <fnlo1995@gmail.com>
Reviewed-by: Matheus Alcantara <matheusssilv97@gmail.com>
Reviewed-by: Jim Jones <jim.jones@uni-muenster.de>
Discussion: https://postgr.es/m/357C774A-ECE9-4455-B641-315205D4D9A1@gmail.com

[verified-by-code: git show db5ed03217b]

Example B — bugfix with named introducing commit

Apply encoding conversion in COPY TO FORMAT JSON

CopyToJsonOneRow() sent the output of composite_to_json() directly
via CopySendData() without encoding conversion.  The text and CSV
paths convert per-attribute via pg_server_to_any() when
need_transcoding is true, but the JSON path skipped this entirely.

This meant COPY ... TO ... WITH (FORMAT json, ENCODING 'LATIN1') on
a UTF-8 server silently produced UTF-8 output, and COPY TO STDOUT
with a non-UTF-8 client_encoding would send unconverted bytes to
the client.

Apply pg_server_to_any() to the whole JSON buffer after
composite_to_json() returns, converting to the requested file
encoding when it differs from the server encoding.  Tests cover
both the explicit ENCODING option and the implicit case where
file_encoding is inherited from client_encoding.

Introduced by 7dadd38cda9 (json format for COPY TO).

Author: Ayush Tiwari <ayushtiwari.slg01@gmail.com>
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
Discussion: https://postgr.es/m/CAJTYsWX-jsLzxGRAb-dWnEpGYRPbDYHwce8LctVE92LiDfM2Jw@mail.gmail.com

[verified-by-code: git show 7dc5bbcf220]

Example C — backpatched fix, doc-prefix subject

doc: Correct the timeline for OAuth's shutdown_cb

During original feature development, the OAuth validator shutdown
callback was invoked via before_shmem_exit(). That was changed to use a
reset callback before commit, but I forgot to update the documentation
for validator developers.

Correct this and backport to 18, where OAuth was introduced. The
callback is invoked whenever the server is "finished" with token
validation. (We make no stronger guarantees here, in the hopes that this
API might successfully navigate future multifactor authentication
support and/or changes to the server threading model.)

Reported-by: Zsolt Parragi <zsolt.parragi@percona.com>
Reviewed-by: Zsolt Parragi <zsolt.parragi@percona.com>
Reviewed-by: Chao Li <li.evan.chao@gmail.com>
Discussion: https://postgr.es/m/CAN4CZFOuMb_gnLvCwRdMybg_k8WRNJTjcij%2BPoQkuQHDUzxGWg%40mail.gmail.com
Backpatch-through: 18

[verified-by-code: git show 08127c641c0]

7. Catalog-version bumps

If your patch changes anything that affects on-disk format or system catalog layout, you bump CATALOG_VERSION_NO (and possibly PG_CONTROL_VERSION, XLOG_PAGE_MAGIC, PGSTAT_FILE_FORMAT_ID). The bump itself is a one-line #define change usually done by the committer at apply time; you do not put a paragraph about it in the commit body, but the bump is included in the same commit. [from-wiki: Committing_checklist — "Consider… CATALOG_VERSION_NO, PG_CONTROL_VERSION, XLOG_PAGE_MAGIC, PGSTAT_FILE_FORMAT_ID."]

8. Backpatching mechanics

When the same fix lands on multiple branches, the commit message must be identical across branches so tooling can match them up for release notes. The only thing that varies between the branches is the diff itself (resolved conflicts). [from-wiki: Committing_checklist — "Commit messages for multiple branches should be identical when back-patching, in order to have tooling recognize the redundancy for purposes of compiling release notes."]

The trailer Backpatch-through: 14 appears on all the cherry-picked copies, naming the oldest branch — not "Backpatch from master" or similar.

9. Checklist before git commit

1. Subject is imperative, capitalized, no period, under ~64 chars.
2. Subject has a subsystem prefix only if the change is scoped to one.
3. Body wraps near 72–76 cols and explains why.
4. Trailer block: Author: (if not you), Reported-by: / Reviewed-by: as applicable, Discussion: https://postgr.es/m/..., Backpatch-through: only if backpatching.
5. No Co-Authored-By: Claude, no Signed-off-by:, no emoji, no conventional-commits prefix.
6. If the diff touches catalog layout, the same commit bumps CATALOG_VERSION_NO.

When uncertain, run git log --format='%n----- %h %s%n%n%b' -20 and mirror the style of the most recent committer in that subsystem.

Cross-references

• .claude/skills/meta-commit-style/SKILL.md — the other commit style (postgres-claude meta repo). Distinct: requires Co-Authored-By, uses ft(scope): prefix.
• .claude/skills/patch-submission/SKILL.md — the surrounding flow: format-patch + cover letter + CF registration. This skill produces the per-commit messages it wraps.
• .claude/skills/review-checklist/SKILL.md — committer-readiness phase pulls from this skill.
• .claude/skills/coding-style/SKILL.md — the diff this message describes.
• knowledge/community/patch-workflow.md — long-form workflow context.