How to fix conflict: Database conflict, usually related to concurrent requests in Supabase

409 Conflict
Database conflict, usually related to concurrent requests

// Example retry logic
async function executeWithRetry(fn, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fn();
    } catch (error) {
      if (error.status === 409 && i < maxRetries - 1) {
        // Exponential backoff: 100ms, 200ms, 400ms, etc.
        await new Promise(resolve =>
          setTimeout(resolve, Math.pow(2, i) * 100)
        );
        continue;
      }
      throw error;
    }
  }
}

// Usage
const result = await executeWithRetry(async () => {
  return await supabase
    .from('your_table')
    .update({ column: value })
    .eq('id', id);
});

// Update your table schema to include version column
await supabase.from('users').create({
  // ... other columns
  version: { type: 'bigint', defaultValue: 1 }
});

// When updating, check the version
const { error } = await supabase
  .from('users')
  .update({
    name: newName,
    version: version + 1
  })
  .eq('id', userId)
  .eq('version', version); // Only update if version matches

if (error) {
  // Version mismatch means the row changed, refetch and retry
  const latest = await supabase
    .from('users')
    .select()
    .eq('id', userId)
    .single();

  // Retry with fresh data
}

// Lock the row for update before modifying it
const result = await supabase.rpc('lock_and_update', {
  row_id: id,
  new_value: value
});

CREATE OR REPLACE FUNCTION lock_and_update(row_id UUID, new_value TEXT)
RETURNS TABLE(success BOOLEAN) AS $$
BEGIN
  -- This locks the row so other transactions wait
  UPDATE my_table
  SET value = new_value
  WHERE id = row_id;

  RETURN QUERY SELECT true;
END;
$$ LANGUAGE plpgsql;

// BAD: Long transaction including API calls
const transaction = await supabase.from('orders').select().single();
const externalData = await fetch('https://api.example.com/data'); // Slow!
await supabase.from('orders').update({ processed: true });

// GOOD: Minimal transaction, fetch data separately
const externalData = await fetch('https://api.example.com/data'); // Outside transaction
await supabase.from('orders').update({ processed: true });