Skill Introduction

Overview

PostgreSQL database patterns for query optimization, schema design, indexing, and security. Quick reference for common patterns, index types, data types, and anti-pattern detection. Based on Supabase best practices.

Core value

Turns reusable Documentation know-how into an installable skill, helping users complete github, community, cursor work faster.

Target users

Developers, testers, and maintainers who handle Documentation tasks in Focus Code.
Teams that already trust workflows or content from affaan-m.
Users who want standardized prompts, steps, or conventions instead of repeating setup work.

Best practices

Read the skill content first to confirm required inputs, expected outputs, and dependencies.
Try it on a small task before relying on it for critical work.
Add project-specific constraints such as coding style, target platform, test expectations, and delivery format.
For external sources, verify the source link, version, and recent maintenance activity.

Best use cases

Tasks related to github, community, cursor that need a reusable execution flow.
Converting a community repo, team convention, or personal workflow into day-to-day assistance.
Starting from a proven skill instead of writing prompts or procedures from scratch.

Limits and boundaries

Results depend on the quality of the original skill content and may need human correction.
It does not replace code review, tests, security review, or professional judgment.
External tools, APIs, account permissions, and local dependencies still need separate setup.

Differentiation

Structured around Documentation, making it easier to discover and reuse than loose prompt snippets.
Marked as GitHub, which helps users judge trust and maintenance expectations.
Keeps the original source link available for repository, documentation, or discussion follow-up.
Tagged with github, community, cursor, so it can be filtered by concrete task intent.

Install and use

Install

Copy Install Command

focus install postgres-patterns-480812

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Detail Preview

SKILL.md

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name: postgres-patterns description: > PostgreSQL database patterns for query optimization, schema design, indexing, and security. Quick reference for common patterns, index types, data types, and anti-pattern detection. Based on Supabase best practices. metadata: origin: ECC credit: Supabase team (MIT License)

PostgreSQL Patterns

Quick reference for PostgreSQL best practices. For detailed guidance, use the database-reviewer agent.

When to Activate

Writing SQL queries or migrations
Designing database schemas
Troubleshooting slow queries
Implementing Row Level Security
Setting up connection pooling

Quick Reference

Index Cheat Sheet

Query Pattern	Index Type	Example
`WHERE col = value`	B-tree (default)	`CREATE INDEX idx ON t (col)`
`WHERE col > value`	B-tree	`CREATE INDEX idx ON t (col)`
`WHERE a = x AND b > y`	Composite	`CREATE INDEX idx ON t (a, b)`
`WHERE jsonb @> '{}'`	GIN	`CREATE INDEX idx ON t USING gin (col)`
`WHERE tsv @@ query`	GIN	`CREATE INDEX idx ON t USING gin (col)`
Time-series ranges	BRIN	`CREATE INDEX idx ON t USING brin (col)`

Data Type Quick Reference

Use Case	Correct Type	Avoid
IDs	`bigint`	`int`, random UUID
Strings	`text`	`varchar(255)`
Timestamps	`timestamptz`	`timestamp`
Money	`numeric(10,2)`	`float`
Flags	`boolean`	`varchar`, `int`

Common Patterns

Composite Index Order:

-- Equality columns first, then range columns
CREATE INDEX idx ON orders (status, created_at);
-- Works for: WHERE status = 'pending' AND created_at > '2024-01-01'

Covering Index:

CREATE INDEX idx ON users (email) INCLUDE (name, created_at);
-- Avoids table lookup for SELECT email, name, created_at

Partial Index:

CREATE INDEX idx ON users (email) WHERE deleted_at IS NULL;
-- Smaller index, only includes active users

RLS Policy (Optimized):

CREATE POLICY policy ON orders
  USING ((SELECT auth.uid()) = user_id);  -- Wrap in SELECT!

UPSERT:

INSERT INTO settings (user_id, key, value)
VALUES (123, 'theme', 'dark')
ON CONFLICT (user_id, key)
DO UPDATE SET value = EXCLUDED.value;

Cursor Pagination:

SELECT * FROM products WHERE id > $last_id ORDER BY id LIMIT 20;
-- O(1) vs OFFSET which is O(n)

Queue Processing:

UPDATE jobs SET status = 'processing'
WHERE id = (
  SELECT id FROM jobs WHERE status = 'pending'
  ORDER BY created_at LIMIT 1
  FOR UPDATE SKIP LOCKED
) RETURNING *;

Anti-Pattern Detection

-- Find unindexed foreign keys
SELECT conrelid::regclass, a.attname
FROM pg_constraint c
JOIN pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = ANY(c.conkey)
WHERE c.contype = 'f'
  AND NOT EXISTS (
    SELECT 1 FROM pg_index i
    WHERE i.indrelid = c.conrelid AND a.attnum = ANY(i.indkey)
  );

-- Find slow queries
SELECT query, mean_exec_time, calls
FROM pg_stat_statements
WHERE mean_exec_time > 100
ORDER BY mean_exec_time DESC;

-- Check table bloat
SELECT relname, n_dead_tup, last_vacuum
FROM pg_stat_user_tables
WHERE n_dead_tup > 1000
ORDER BY n_dead_tup DESC;

Configuration Template

-- Connection limits (adjust for RAM)
ALTER SYSTEM SET max_connections = 100;
ALTER SYSTEM SET work_mem = '8MB';

-- Timeouts
ALTER SYSTEM SET idle_in_transaction_session_timeout = '30s';
ALTER SYSTEM SET statement_timeout = '30s';

-- Monitoring
CREATE EXTENSION IF NOT EXISTS pg_stat_statements;

-- Security defaults
REVOKE ALL ON SCHEMA public FROM public;

SELECT pg_reload_conf();

When to Use This Skill

Writing SQL queries
Designing database schemas
Optimizing query performance
Implementing Row Level Security
Troubleshooting database issues
Setting up PostgreSQL configuration

Based on Supabase Agent Skills (credit: Supabase team) (MIT License)

postgres patterns