Supabase Administration Expert

Master Supabase schema design, Row Level Security policies, migrations, and performance optimization for production applications.

When to Use

✅ USE this skill for:

• Row Level Security (RLS) policy design and debugging
• Database migrations and schema changes
• Auth integration (triggers, profile creation)
• Query performance optimization
• Supabase-specific SQL patterns (auth.uid(), auth.jwt())

❌ DO NOT use for:

• Supabase Auth UI configuration → use Supabase dashboard docs
• Edge Functions → use cloudflare-worker-dev skill
• General PostgreSQL without Supabase context → use standard SQL resources
• Client-side Supabase SDK usage → use Supabase JS docs

Core Competencies

1. Row Level Security (RLS)

Always Enable RLS on User Tables:

ALTER TABLE your_table ENABLE ROW LEVEL SECURITY;

Policy Patterns:

-- Public read, authenticated write
CREATE POLICY "Public read" ON posts FOR SELECT USING (true);
CREATE POLICY "Owners can write" ON posts FOR INSERT
  WITH CHECK (auth.uid() = user_id);

-- Owner-only access
CREATE POLICY "Users own their data" ON profiles
  FOR ALL USING (auth.uid() = id);

-- Role-based access
CREATE POLICY "Admins can do anything" ON content
  FOR ALL USING (
    EXISTS (
      SELECT 1 FROM profiles
      WHERE profiles.id = auth.uid()
      AND profiles.role = 'admin'
    )
  );

Performance-Critical: Index auth.uid() Columns:

-- 100x performance improvement for RLS policies
CREATE INDEX idx_posts_user_id ON posts(user_id);
CREATE INDEX idx_profiles_id ON profiles(id);

Subquery Optimization for JWT Functions:

-- BAD: JWT parsed for every row
CREATE POLICY "slow" ON posts FOR SELECT
  USING (user_id = auth.uid());

-- GOOD: JWT parsed once via subquery
CREATE POLICY "fast" ON posts FOR SELECT
  USING (user_id = (SELECT auth.uid()));

2. Migration Best Practices

File Naming Convention:

supabase/migrations/
├── 001_initial_schema.sql
├── 002_add_profiles_trigger.sql
├── 003_forum_tables.sql
└── 004_add_rls_policies.sql

Migration Template:

-- Migration: 005_feature_name
-- Description: What this migration does
-- Author: name
-- Date: YYYY-MM-DD

-- Up migration
BEGIN;

-- Your DDL here
CREATE TABLE ...;
ALTER TABLE ...;
CREATE POLICY ...;

COMMIT;

-- Down migration (as comment for reference)
-- DROP TABLE ...;
-- DROP POLICY ...;

Safe Migration Patterns:

-- Add column with default (no table lock)
ALTER TABLE users ADD COLUMN status text DEFAULT 'active';

-- Add NOT NULL constraint safely
ALTER TABLE users ADD COLUMN email text;
UPDATE users SET email = 'unknown@example.com' WHERE email IS NULL;
ALTER TABLE users ALTER COLUMN email SET NOT NULL;

-- Create index concurrently (no lock)
CREATE INDEX CONCURRENTLY idx_users_email ON users(email);

3. Auth Integration

Auto-create Profile on Signup:

-- Function to create profile
CREATE OR REPLACE FUNCTION public.handle_new_user()
RETURNS TRIGGER AS $$
BEGIN
  INSERT INTO public.profiles (id, email, display_name)
  VALUES (
    NEW.id,
    NEW.email,
    COALESCE(NEW.raw_user_meta_data->>'display_name', split_part(NEW.email, '@', 1))
  );
  RETURN NEW;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

-- Trigger on auth.users
CREATE TRIGGER on_auth_user_created
  AFTER INSERT ON auth.users
  FOR EACH ROW EXECUTE FUNCTION public.handle_new_user();

Check Auth Status in Policies:

-- Authenticated users only
CREATE POLICY "Authenticated access" ON data
  FOR SELECT USING (auth.role() = 'authenticated');

-- Get current user's ID
SELECT auth.uid();

-- Get current user's JWT claims
SELECT auth.jwt();

4. Common Schema Patterns

Timestamps with Defaults:

CREATE TABLE posts (
  id uuid PRIMARY KEY DEFAULT gen_random_uuid(),
  user_id uuid REFERENCES auth.users(id) ON DELETE CASCADE,
  content text NOT NULL,
  created_at timestamptz DEFAULT now(),
  updated_at timestamptz DEFAULT now()
);

-- Auto-update updated_at
CREATE OR REPLACE FUNCTION update_updated_at()
RETURNS TRIGGER AS $$
BEGIN
  NEW.updated_at = now();
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER update_posts_updated_at
  BEFORE UPDATE ON posts
  FOR EACH ROW EXECUTE FUNCTION update_updated_at();

Soft Delete Pattern:

ALTER TABLE posts ADD COLUMN deleted_at timestamptz;

CREATE POLICY "Hide deleted" ON posts
  FOR SELECT USING (deleted_at IS NULL);

Full-Text Search:

-- Add search vector column
ALTER TABLE posts ADD COLUMN search_vector tsvector;

-- Create GIN index
CREATE INDEX idx_posts_search ON posts USING GIN(search_vector);

-- Update function
CREATE OR REPLACE FUNCTION posts_search_update()
RETURNS TRIGGER AS $$
BEGIN
  NEW.search_vector := to_tsvector('english', COALESCE(NEW.title, '') || ' ' || COALESCE(NEW.content, ''));
  RETURN NEW;
END;
$$ LANGUAGE plpgsql;

-- Search query
SELECT * FROM posts
WHERE search_vector @@ plainto_tsquery('english', 'search terms');

5. Debugging RLS Issues

Common Problem: Empty Results, No Error

-- Check if RLS is enabled
SELECT tablename, rowsecurity FROM pg_tables WHERE schemaname = 'public';

-- List all policies
SELECT * FROM pg_policies WHERE tablename = 'your_table';

-- Test as specific role
SET ROLE anon;
SELECT * FROM your_table LIMIT 1;
RESET ROLE;

-- Test with specific user
SET request.jwt.claims TO '{"sub": "user-uuid-here"}';
SELECT * FROM your_table;

Diagnostic Query:

-- Check what the current user can see
SELECT
  auth.uid() as current_user,
  auth.role() as current_role,
  (SELECT count(*) FROM your_table) as visible_rows;

Quick Reference

References

See /references/ for detailed guides:

• rls-patterns.md - Advanced RLS policy patterns
• migration-checklist.md - Pre-deployment checklist
• performance-tuning.md - Query and index optimization
• social-schema.md - Schema patterns for social features