supabase-advanced-troubleshooting

# Supabase Advanced Troubleshooting ## Overview When basic debugging does not reveal the root cause, you need deep PostgreSQL diagnostics: `pg_stat_statements` to find the slowest queries by cumulative execution time, `pg_locks` to detect lock contention and deadlocks, `pg_stat_activity` to find connection leaks, RLS policy conflict analysis to diagnose silent data filtering, Edge Function cold start profiling, and Realtime channel drop investigation. This skill covers every advanced diagnostic technique with real SQL queries and `createClient` from `@supabase/supabase-js`. **When to use:** Slow query investigation, lock contention causing timeouts, connection pool exhaustion from leaks, RLS policies that silently filter or conflict, Edge Functions with unpredictable latency, or Realtime subscriptions that disconnect intermittently. ## Prerequisites - Supabase project with `pg_stat_statements` extension enabled - Direct database access via SQL Editor or `psql` - `@supabase/supabase-js` v2+ installed in your project - Supabase CLI for Edge Function logs - Familiarity with PostgreSQL system catalogs ## Instructions ### Step 1: pg_stat_statements and Slow Query Analysis Enable and query `pg_stat_statements` to find the most expensive queries by total execution time, calls, and rows processed. **Enable the extension and query slow queries:** ```sql -- Enable pg_stat_statements (run once) CREATE EXTENSION IF NOT EXISTS pg_stat_statements; -- Top 10 slowest queries by to...