SKILL.md
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-- ✅ GOOD: Structured JSONB with validation
ALTER TABLE orders ADD CONSTRAINT valid_status
CHECK (data->>'status' IN ('pending', 'shipped', 'delivered'));
### Array Operations Review
-- ❌ BAD: Inefficient array operations
SELECT * FROM products WHERE 'electronics' = ANY(categories); -- No index
-- ✅ GOOD: GIN indexed array queries
CREATE INDEX idx_products_categories ON products USING gin(categories);
SELECT * FROM products WHERE categories @> ARRAY['electronics'];
-- ❌ BAD: Array concatenation in loops
-- This would be inefficient in a function/procedure
-- ✅ GOOD: Bulk array operations
UPDATE products SET categories = categories || ARRAY['new_category']
WHERE id IN (SELECT id FROM products WHERE condition);
### PostgreSQL Schema Design Review
-- ❌ BAD: Not using PostgreSQL features
CREATE TABLE users (
id INTEGER,
email VARCHAR(255),
created_at TIMESTAMP
);
-- ✅ GOOD: PostgreSQL-optimized schema
CREATE TABLE users (
id BIGSERIAL PRIMARY KEY,
email CITEXT UNIQUE NOT NULL, -- Case-insensitive email
created_at TIMESTAMPTZ DEFAULT NOW(),
metadata JSONB DEFAULT '{}',
CONSTRAINT valid_email CHECK (email ~* '^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$')
);
-- Add JSONB GIN index for metadata queries
CREATE INDEX idx_users_metadata ON users USING gin(metadata);
### Custom Types and Domains
-- ❌ BAD: Using generic types for specific data
CREATE TABLE transactions (
amount DECIMAL(10,2),
currency VARCHAR(3),
status VARCHAR(20)
);
-- ✅ GOOD: PostgreSQL custom types
CREATE TYPE currency_code AS ENUM ('USD', 'EUR', 'GBP', 'JPY');
CREATE TYPE transaction_status AS ENUM ('pending', 'completed', 'failed', 'cancelled');
CREATE DOMAIN positive_amount AS DECIMAL(10,2) CHECK (VALUE > 0);
CREATE TABLE transactions (
amount positive_amount NOT NULL,
currency currency_code NOT NULL,
status transaction_status DEFAULT 'pending'
);
## 🔍 PostgreSQL-Specific Anti-Patterns
### Performance Anti-Patterns
- **Avoiding PostgreSQL-specific indexes**: Not using GIN/GiST for appropriate data types
- **Misusing JSONB**: Treating JSONB like a simple string field
- **Ignoring array operators**: Using inefficient array operations
- **Poor partition key selection**: Not leveraging PostgreSQL partitioning effectively
### Schema Design Issues
- **Not using ENUM types**: Using VARCHAR for limited value sets
- **Ignoring constraints**: Missing CHECK constraints for data validation
- **Wrong data types**: Using VARCHAR instead of TEXT or CITEXT
- **Missing JSONB structure**: Unstructured JSONB without validation
### Function and Trigger Issues
-- ❌ BAD: Inefficient trigger function
CREATE OR REPLACE FUNCTION update_modified_time()
RETURNS TRIGGER AS $$
BEGIN
NEW.updated_at = NOW(); -- Should use TIMESTAMPTZ
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
-- ✅ GOOD: Optimized trigger function
CREATE OR REPLACE FUNCTION update_modified_time()
RETURNS TRIGGER AS $$
BEGIN
NEW.updated_at = CURRENT_TIMESTAMP;
RETURN NEW;
END;
$$ LANGUAGE plpgsql;
-- Set trigger to fire only when needed
CREATE TRIGGER update_modified_time_trigger
BEFORE UPDATE ON table_name
FOR EACH ROW
WHEN (OLD. IS DISTINCT FROM NEW.)
EXECUTE FUNCTION update_modified_time();
## 📊 PostgreSQL Extension Usage Review
### Extension Best Practices
-- ✅ Check if extension exists before creating
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
CREATE EXTENSION IF NOT EXISTS "pgcrypto";
CREATE EXTENSION IF NOT EXISTS "pg_trgm";
-- ✅ Use extensions appropriately
-- UUID generation
SELECT uuid_generate_v4();
-- Password hashing
SELECT crypt('password', gen_salt('bf'));
-- Fuzzy text matching
SELECT word_similarity('postgres', 'postgre');
## 🛡️ PostgreSQL Security Review
### Row Level Security (RLS)
-- ✅ GOOD: Implementing RLS
ALTER TABLE sensitive_data ENABLE ROW LEVEL SECURITY;
CREATE POLICY user_data_policy ON sensitive_data
FOR ALL TO application_role
USING (user_id = current_setting('app.current_user_id')::INTEGER);
### Privilege Management
-- ❌ BAD: Overly broad permissions
GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO app_user;
-- ✅ GOOD: Granular permissions
GRANT SELECT, INSERT, UPDATE ON specific_table TO app_user;
GRANT USAGE ON SEQUENCE specific_table_id_seq TO app_user;