DB Sculptor

What it does

When your agent uses it

• User asks to design schema
• Create migrations
• Optimize slow queries
• Choose between SQL/NoSQL

Example prompts

• “/db-sculptor”

Requirements

• Node.js
• A Bash shell
• Compatibility (from SKILL.md): opencode
• Pre-approved tools (allowed-tools): Read, Bash, Write, Grep

Workflow steps

5 steps, taken from the step headings in SKILL.md.

1. 1Model for access patterns
2. 2Primary key strategy
3. 3Add indexes strategically
4. 4Optimize queries
5. 5Safe migrations (expand/contract)

What it can do on your machine

Read from SKILL.md and the folder at commit 4c68e5b. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Bash
  • Write
  • Grep

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Ships 1 file in scripts/ (Shell), which the agent can run.

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  opencode

  From compatibility in the SKILL.md frontmatter.

Context cost

DB Sculptor loads about 3.1k tokens when it runs, and up to ~18k if it reads all its reference files. Until then it costs about 125 tokens; SKILL.md has 953 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~125

When it runs · the whole SKILL.md, loaded when a task matches

~3.1k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~18k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NotePre-approves every shell command (allowed-tools: Bash)SKILL.md

  allowed-tools: Read, Bash, Write, Grep

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from EliasOulkadi/shokunin at commit 4c68e5b, republished under its MIT licence (© EliasOulkadi). 953 words, ~3,112 tokens.

name

db-sculptor

description

Design database schemas with Prisma/Drizzle, PostgreSQL index strategy (B-tree, GIN, GiST, BRIN, Hash), query optimization (EXPLAIN ANALYZE), migration safety (expand/contract, zero-downtime), and sharding/partitioning. Use when user asks to design schema, create migrations, optimize slow queries, add indexes, choose between SQL/NoSQL, or set up Prisma/Drizzle. Do NOT use for data warehouse dimensional modeling, ETL pipeline design, or non-relational (MongoDB, DynamoDB) schema design.

allowed-tools

Read, Bash, Write, Grep

compatibility

opencode

triggers

design database schema, Prisma schema, Drizzle schema, PostgreSQL index, optimize query, EXPLAIN ANALYZE, create migration, zero-downtime migration, database…

negatives

database backup, database administration, data warehouse, ETL pipeline, MongoDB, DynamoDB, non-relational

license

MIT

metadata.workflow

backend

metadata.audience

developers

metadata.version

4.0.0

metadata.author

shokunin

EXPLAIN (ANALYZE, BUFFERS) SELECT * FROM orders WHERE user_id = 123 AND status = 'active';

-- Slow (~235ms): Seq Scan on 500k rows
-- Fix: composite index
CREATE INDEX CONCURRENTLY idx_orders_user_status
  ON orders (user_id, status, created_at DESC);

-- After fix: Index Only Scan, ~0.3ms

-- Pattern 1: Function on indexed column → expression index
-- Slow: WHERE LOWER(email) = 'user@example.com'
-- Fix:
CREATE INDEX idx_users_email_lower ON users (LOWER(email));

-- Pattern 2: Missing FK index → Nested Loop join
-- Slow: SELECT * FROM orders JOIN users ON orders.user_id = users.id WHERE users.name = 'Alice'
-- Fix:
CREATE INDEX idx_orders_user_id ON orders (user_id);

-- Pattern 3: ORDER BY + LIMIT without index → full sort
-- Slow: SELECT * FROM events ORDER BY created_at DESC LIMIT 20;
-- Fix:
CREATE INDEX idx_events_created_at ON events (created_at DESC);

-- Pattern 4: COUNT on large table without WHERE → estimated count
-- Slow: SELECT COUNT(*) FROM huge_table;
-- Fix (approximate):
SELECT reltuples::bigint FROM pg_class WHERE relname = 'huge_table';

-- Pattern 5: Pagination with OFFSET → performance degrades
-- Slow: SELECT * FROM items ORDER BY id LIMIT 20 OFFSET 100000;
-- Fix (keyset pagination):
SELECT * FROM items WHERE id > 100000 ORDER BY id LIMIT 20;

-- Pattern 6: Unused indexes bloating writes
-- Identify unused indexes:
SELECT schemaname, tablename, indexname, idx_scan
FROM pg_stat_user_indexes
WHERE idx_scan = 0
ORDER BY pg_relation_size(indexrelid) DESC;

-- Pattern 7: Parallel query for large scans
-- Force parallel workers on large analytical queries:
SET max_parallel_workers_per_gather = 4;
EXPLAIN (ANALYZE, BUFFERS) SELECT ...;

// prisma/schema.prisma
model User {
  id        String   @id @default(uuid()) @db.Uuid
  email     String   @unique
  timezone  String?  // Phase 1: nullable
  createdAt DateTime @default(now()) @map("created_at")
  updatedAt DateTime @updatedAt @map("updated_at")

  @@index([email])
  @@map("users")
}

// db/schema/users.ts
import { pgTable, text, timestamp, uuid, index } from "drizzle-orm/pg-core";

export const users = pgTable("users", {
  id: uuid("id").defaultRandom().primaryKey(),
  email: text("email").notNull().unique(),
  timezone: text("timezone"), // Phase 1: nullable
  createdAt: timestamp("created_at", { withTimezone: true }).defaultNow().notNull(),
  updatedAt: timestamp("updated_at", { withTimezone: true }).defaultNow().notNull(),
}, (table) => ({
  emailIdx: index("idx_users_email").on(table.email),
}));

// Migration command: npx drizzle-kit generate && npx drizzle-kit migrate

-- Phase 1 (expand): Add column as nullable
ALTER TABLE users ADD COLUMN timezone text;

-- Phase 2 (backfill): Fill data in separate deployment
UPDATE users SET timezone = 'UTC' WHERE timezone IS NULL;

-- Phase 3 (contract): Make NOT NULL, clean up
ALTER TABLE users ALTER COLUMN timezone SET NOT NULL;

-- Phase 4 (future): Drop old column
ALTER TABLE users DROP COLUMN old_timezone;

# pgbouncer.ini
[databases]
mydb = host=localhost port=5432 dbname=mydb

[pgbouncer]
listen_addr = 0.0.0.0
listen_port = 6432
auth_type = scram-sha-256
auth_file = /etc/pgbouncer/userlist.txt
pool_mode = transaction
default_pool_size = 25
max_client_conn = 200
max_db_connections = 25

© EliasOulkadi, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files (scripts, references, assets) in .pack/skills/db-sculptor of EliasOulkadi/shokunin.

• SKILL.md
• assets/prisma-schema.template.prisma
• references/index-strategies.md
• references/migration-patterns.md
• references/query-optimization.md
• scripts/generate-schema.sh

Open the folder on GitHubat commit 4c68e5b