DongHyeonkaandClaude Opus 5
b2963105a8
The keycloak project ended with four open questions that design could not
settle. A two-VM lab was built to answer them by measurement, and this is
that material: 26 experiments, 125 raw command outputs, 22 browser captures.
Follows the import procedure in README.md.
source/ the originating repository verbatim — 78 documents, 28 SVGs,
8 manifests, plus .source-revision recording the commit
final/ the SSOT
document.md 729 lines written from the 29 experiment documents, not
concatenated: what was predicted, what was measured, and
where the measurement itself was wrong
evidence/raw 125 outputs, flattened to <experiment>__<file> because
the originals collided (01-baseline.txt appeared three
times) and the audit only globs the top level
evidence/meta one per raw file; command and exitCode are null and the
README says why rather than inventing them
evidence/browser 22 captures
assets/ three diagrams through techviz
.techviz/ their VizSpecs
A separate project rather than an addition to keycloak: the B-layer answers
that project's four questions, but the A, C and D layers are about cluster
failure, SSO and operations, and one document.md should hold one subject.
The four question records there can point here through 관계.
Recorded rather than papered over: only three of the 28 diagrams were
remade. The repository forbids hand-drawn SVG and forbids titles inside the
canvas; all 28 originals carry both, so converting them is redrawing, not
reformatting. They stay in source/ and the gap is written into the document.
verify-pipeline.py passes. audit-records.py reports no issues.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
56 lines
3.0 KiB
Markdown
56 lines
3.0 KiB
Markdown
---
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kind: CONCEPT
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slug: adapter-outbound-persistence-jpa-c04
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title: offset을 표현할 수 없는 타입과 count 질의 없는 hasNext
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topic: delivery-and-settlement-models
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project: clean-architecture-backend-template
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status: 게시 전
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sourceRevision: 21234e38cdb9a926cbc92bb97a2aee2e4a7d2916
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rootTreeNode: concept:adapter-outbound-persistence-jpa-c04
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evidenceCapturedOn: 2026-09-01
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assets:
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- key: adapter-outbound-persistence-jpa-c04
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file: ../../../final/evidence/rendered/adapter-outbound-persistence-jpa-c04.svg
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- key: adapter-outbound-persistence-jpa-c04-diagram
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file: ../../../final/assets/diagrams/adapter-outbound-persistence-jpa-c04.svg
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evidence:
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- ../../../final/evidence/raw/adapter-outbound-persistence-jpa-c04.txt
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source:
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- 원본 분석 절은 analysis/05-adapter-outbound-persistence-jpa.md#L302 이다.
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module: adapter-outbound-persistence-jpa
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---
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# offset을 표현할 수 없는 타입과 count 질의 없는 hasNext
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질의 API가 offset과 page number를 타입으로 표현하지 않고, `fetchSize()`가 size + 1을 반환해 별도 count 질의 없이 `hasNext`를 정한다.
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## 본문
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<!-- body:start -->
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offset/page number를 아예 표현하지 않으므로 keyset API를 사용하는 consumer가 실수로 large offset pagination으로 회귀하기 어렵다.
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## 질의 API가 표현하지 않는 것
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:::evidence key="adapter-outbound-persistence-jpa-c04-diagram" alt="정렬 키와 size 더하기 1과 서명된 커서가 질의 API 안에 놓이고 offset과 total count 질의가 바깥에 빗금으로 놓인다" caption="질의 API가 표현하지 않는 것" zoom="false"
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:::
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## count 질의 없이 hasNext를 정한다
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`fetchSize()`는 요청 size + 1을 반환한다. 즉 별도 count query 없이 한 row를 더 읽어 `hasNext`를 판단하는 계약이다. hasNext=true이면 nextCursor 필수, terminal slice이면 nextCursor 금지, items는 defensive copy. page number/total count가 없다는 것은 API omission이 아니라 의도된 성능 정책이다 — "keyset을 쓰면서 매번 count(*)도 수행"하는 모순을 contract shape에서 제거한다.
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## QueryName 참조 위치
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:::evidence key="adapter-outbound-persistence-jpa-c04" alt="코드베이스에서 QueryName 를 검색한 출력 21줄. 이 기록이 세는 참조가 그 출력에 그대로 보인다." caption="QueryName 코드베이스 검색 — 21줄 · exit 0" zoom="true"
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:::
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## raw SQL이 metric identity가 될 수 없다
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`QueryName`도 bounded registry key다. `QueryObservation.start(QueryName)` → `QueryScope` 구조에서 `QueryScope.failure` 문서가 "throwable message를 log하지 말 것"을 직접 계약한다. Micrometer implementation이 이를 실제로 지키는지는 observation sub-scope에서 확인한다.
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## backend가 없어도 흐름이 갈라지지 않는다
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`NoopQueryObservation`은 backend가 없을 때도 caller control flow가 갈라지지 않게 singleton no-op scope를 제공한다. app-bootstrap `JpaObservabilityAutoConfiguration`에서 actual fallback consumer가 존재한다.
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<!-- body:end -->
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