Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add sigistry/marketplace --skill schema-antipatternsgit clone --depth 1 https://github.com/sigistry/marketplaceWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/sigistry/marketplace/schema-antipatterns)<a href="https://agentmods.dev/skills/sigistry/marketplace/schema-antipatterns"><img src="https://agentmods.dev/badge/skills/sigistry/marketplace/schema-antipatterns/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/sigistry/marketplace/schema-antipatterns"><img src="https://agentmods.dev/badge/skills/sigistry/marketplace/schema-antipatterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00093 | $0.00909 |
| Opus 5 | $0.00046 | $0.00454 |
| Sonnet 5 | $0.00019 | $0.00182 |
| Haiku 4.5 | $0.00009 | $0.00091 |
Grade A, and why
schema-antipatterns scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Schema Antipatterns
Purpose
Provide a standardized catalog of relational schema design anti-patterns and ORM query anti-patterns, so schema reviews and N+1 hunts are consistent and grounded, statically, from DDL and source, with no database connection. These are the recurring mistakes that a DBA would flag on sight and that a team without one re-introduces every sprint.
Schema anti-pattern catalog
| Category | Anti-pattern | Why it bites | Correct choice |
|---|---|---|---|
| Keys | No primary key | No stable row identity; replication/tooling breaks | Surrogate bigint/identity or uuid PK |
| Keys | UUID stored as varchar(36) |
2–3× storage, slow joins | uuid (PG) / BINARY(16) (MySQL) |
| Foreign keys | FK column with no index | Every parent delete/join scans the child | Index every FK column |
| Foreign keys | Relationship with no FK constraint | Orphan rows, no referential integrity | Declare the FK (+ ON DELETE action) |
| Types | Money as float/double |
Rounding errors on cents | numeric(12,2) / DECIMAL |
| Types | timestamp without time zone |
Ambiguous instants across zones/DST | timestamptz (PG) / store UTC + document |
| Types | Cargo-cult VARCHAR(255) |
Arbitrary cap, no real meaning | text (PG) or a length that models a real rule |
| Types | Enum as loose varchar |
Typos, no validation | Native ENUM/CHECK-constrained or lookup table |
| Types | Boolean as int/char(1) |
2 and 'Y' sneak in |
Native boolean / TINYINT(1) with CHECK |
| Constraints | Nullable-everything | NULL means "unknown" everywhere; buggy logic | NOT NULL on required columns |
| Constraints | Missing UNIQUE/CHECK |
Duplicate/invalid data | Add the business-rule constraint |
| Indexing | Over-indexing / duplicate index | Write amplification, wasted storage | One index per access pattern; drop prefixes |
| Indexing | Index on low-selectivity boolean | Rarely used, still maintained | Partial index or none |
| Integrity | Soft-delete without partial unique | UNIQUE(email) blocks re-signup after delete |
UNIQUE ... WHERE deleted_at IS NULL |
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 8d ago First seen · 43 lines · 93 tokens per session scan A fcd3bf773b8f
schema-antipatterns is a skill published in the GitHub repository sigistry/marketplace (3 stars, last pushed 2d ago), licensed MIT. It adds 93 tokens to every session and 909 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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