mvcc-isolation-tests SKILL.md skillA
mvcc-isolation-tests from testland/qa is an agent skill: a SKILL.md folder an AI agent loads when a task calls for it.
mdr add testland/qa/mvcc-isolation-tests@v1.2.13Pins v1.2.13 in mdr.lock. Pin the fingerprint instead.
- Audit grade
- A, 17 of 17 checks passed
- Kind
- SKILL.md skill
- Repository
- testland/qa
- Path
plugins/qa-concurrency/skills/mvcc-isolation-tests/SKILL.md- Versions recorded
- 5
- Latest version
- v1.2.13, committed Oct 11, 2026
- First version recorded
- Jul 19, 2026
- Size
- 11,590 bytes
- Repository stars
- 11
- License
- MIT
Build per-database MVCC isolation-level tests - Read Uncommitted vs Read Committed vs Repeatable Read vs Serializable; verify which anomalies are prevented at each level (dirty read, non-repeatable read, phantom read, serialization anomaly, write skew). Per PostgreSQL transaction isolation docs; analogous patterns for MySQL InnoDB, SQL Server, and DynamoDB. Use when two concurrent transactions can touch the same rows (balance debit, seat booking, stock decrement), or before changing a…
Collected from public GitHub. Every version is saved exactly as it was and never changes. Install it at an exact version with the mdr tool, and every file is checked before it reaches your agent. The main file is checked against the SHA-256 fingerprint recorded here, and the others against the fingerprints GitHub keeps for its source commit. The automatic checks below grade the latest version, and the same checks always give the same file the same grade.
What the file says
# mvcc-isolation-tests
Per the [PostgreSQL transaction isolation docs], the four standard
SQL isolation levels permit different anomalies. Production code
must run at the right level - and tests verify both that the
chosen level prevents the anomalies the business cares about AND
that the code copes when the level allows them.
## When to use
- Banking, inventory, booking - anywhere two transactions can
conflict on the same data.
- Choosing or auditing default isolation level for a new service.
- Migration: changing isolation level (e.g., Read Committed →
Repeatable Read) - tests verify nothing relies on old behavior.
## Step 1 - Anomaly catalog
Per the [PostgreSQL transaction isolation docs]:
| Anomaly | What |
|---|---|
| Dirty read | T2 reads uncommitted T1 changes |
| Non-repeatable read | T1 reads X = 5; T2 commits X = 6; T1 re-reads X = 6 |
| Phantom read | T1 query returns 3 rows; T2 inserts row matching predicate; T1 re-runs query, gets 4 rows |
| Serialization anomaly | Concurrent execution produces a result no serial order would |
| Write skew | T1 reads {x, y} = {0, 0}; T2 reads same; both decide based on read-set; both commit; final state inconsistent |
…Read the whole file at its exact version.
How to install
mdr add testland/qa/mvcc-isolation-tests@sha256:e74c0d2be8ee0f1fThe line at the top of this page pins the label v1.2.13, which is what most people want. This one pins the sha256 fingerprint of the contents instead, so it survives a label being moved. Either way the exact version is written to mdr.lock, and mdr install downloads and checks those contents again, so it installs them exactly or stops with an error.
[](https://markdownregistry.com/a/art_ll6bs52kehd3z4js)
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Versions
The registry has recorded 5 versions of this file, between Jul 19, 2026 and Oct 11, 2026, about one every 21 days.
| version | committed | commit | size | audit | |
|---|---|---|---|---|---|
| v1.2.13 latest | 2026-10-11 | a1bd3f7 | 11,590 B | A | view · diff |
| git:20260813.2e5e33b | 2026-08-13 | 2e5e33b | 11,570 B | A | view · diff |
| git:20260724.d4db756 | 2026-07-24 | d4db756 | 11,627 B | A | view · diff |
| git:20260719.53f73b7 | 2026-07-19 | 53f73b7 | 11,742 B | A | view · diff |
| git:20260719.6226ac1 | 2026-07-19 | 6226ac1 | 11,577 B | A | view |
Audit of the latest version
- pass: Frontmatter block present
- pass: Frontmatter declares a name
- pass: Frontmatter declares a description
- pass: Size between 200 bytes and 200 KB (11590 bytes)
- pass: No zero-width or bidi control characters
- pass: No instruction hidden inside an HTML comment
- pass: No link to an exfiltration or paste host
- pass: No credential-shaped string
- pass: No instruction to send local credentials anywhere
- pass: No text hidden with inline styles
- pass: No prompt-injection phrasing
- pass: No curl or wget piped into a shell
- pass: No recursive delete of root, home or parent
- pass: No instruction to read or print local credentials
- pass: No base64 blob over 200 characters
- pass: No link to a raw IP address
- pass: No script tag
Source
testland/qa · 11 stars · license MIT · pushed 2026-10-20 · branch main
API
GET https://markdownregistry.com/api/v1/artifacts/art_ll6bs52kehd3z4js GET https://markdownregistry.com/api/v1/resolve?ref=testland/qa/mvcc-isolation-tests GET https://markdownregistry.com/api/v1/blob/e74c0d2be8ee0f1f4b4ef2d24517fe1cb28dbccde8b21da13248346e219514fa
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