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Data engineering

Supabase CDC Options: Triggers, Webhooks, Realtime Compared

Discover Supabase CDC options: compare triggers, webhooks, and realtime for real-time data sync, plus enterprise solutions like Stacksync for reliable production workflows.

Supabase CDC Options: Triggers, Webhooks, Realtime Compared

Modern Supabase postgresql integration requires efficient change data capture (CDC) mechanisms to maintain real-time data synchronization across distributed systems. Organizations operating complex data architectures face the critical challenge of selecting the right CDC approach to power their bi-directional sync tools and automated data sync between applications.

This analysis compares three primary Supabase CDC approaches: database triggers, webhooks, and Realtime subscriptions, examining their technical capabilities, limitations, and operational impact on database synchronization workflows.

Database Triggers: Transactional Data Consistency

Postgres triggers execute a set of actions automatically on table events such as INSERTs, UPDATEs, DELETEs, or TRUNCATE operations [1], providing the foundation for maintaining data integrity within your Supabase deployment.

Implementation Architecture

Database triggers execute within the same transaction context as the originating data change, ensuring exactly-once processing guarantees. This synchronous execution model provides:

  • Atomic operations: Changes and trigger responses occur within the same transaction boundary
  • Data integrity: Rollback capabilities when trigger execution fails
  • Field-level access: Direct interaction with NEW and OLD record values
  • Performance predictability: Consistent latency patterns for data changes

Here's a trigger implementation for maintaining derived data consistency:

CREATE OR REPLACE FUNCTION update_search_index() RETURNS TRIGGER AS $$
BEGIN
   IF TG_OP = 'INSERT' OR TG_OP = 'UPDATE' THEN
       INSERT INTO search_index (record_id, content)
       VALUES (NEW.id, to_tsvector('english', NEW.title || ' ' || NEW.body))
       ON CONFLICT (record_id) DO UPDATE
       SET content = to_tsvector('english', NEW.title || ' ' || NEW.body);
   ELSIF TG_OP = 'DELETE' THEN
       DELETE FROM search_index WHERE record_id = OLD.id;
   END IF;
   RETURN NULL;
END;
$$ LANGUAGE plpgsql;

CREATE TRIGGER maintain_search_index
AFTER INSERT OR UPDATE OR DELETE ON articles
FOR EACH ROW EXECUTE FUNCTION update_search_index();

Operational Constraints

While triggers provide transactional guarantees, they introduce performance bottlenecks in high-throughput scenarios. Row-by-row execution patterns conflict with bulk operations, and complex trigger cascades create latency accumulation. Additionally, PL/pgSQL debugging limitations increase maintenance overhead compared to application code.

Database Webhooks: Asynchronous External Integration

Database Webhooks are very similar to triggers, and that's because Database Webhooks are just a convenience wrapper around triggers using the pg_net extension. This extension is asynchronous, and therefore will not block your database changes for long-running network requests [2].

Technical Implementation

Database Webhooks leverage the pg_net extension to provide non-blocking HTTP requests, enabling integration with external systems without impacting database transaction performance:

CREATE OR REPLACE FUNCTION post_inserted_order()
   RETURNS trigger
   LANGUAGE plpgsql
AS $$
BEGIN
   PERFORM net.http_post(
     'https://api.example.com/webhook/handler'::text,
     jsonb_build_object(
       'id', NEW.id,
       'name', NEW.name,
       'user_id', NEW.user_id
     ),
     '{"Content-Type": "application/json", "Authorization": "Bearer secret"}'::jsonb
   ) AS request_id;
   RETURN NEW;
END $$;

Delivery Guarantees and Limitations

This extension is asynchronous, and therefore will not block your database changes for long-running network requests [2], but this introduces at-most-once delivery semantics. The _http_response table saves all the response messages from the past 6 hours [3], providing limited error recovery windows without automatic retry mechanisms.

Organizations requiring guaranteed delivery and robust error handling for critical business processes need enterprise-grade alternatives beyond native webhook capabilities.

Realtime Subscriptions: Pub/Sub Event Streaming

Supabase's Realtime Postgres Changes feature allows you to listen to database changes in real-time using the Realtime system. This capability enables you to build responsive, live-updating applications that reflect database changes instantly [4].

Scalability Characteristics

For the Postgres Changes feature, every change event must be checked to see if the subscribed user has access. For instance, if you have 100 users subscribed to a table where you make a single insert, it will then trigger 100 "reads": one for each user. There can be a database bottleneck which limits message throughput [5].

This architecture creates quadratic scaling challenges where subscriber count directly impacts database load, requiring careful capacity planning for high-concurrency scenarios.

Client Implementation

Realtime subscriptions provide developer-friendly interfaces for real-time data synchronization:

const channel = supabase
 .channel('orders-changes')
 .on('postgres_changes', {
   event: 'INSERT',
   schema: 'public',
   table: 'orders'
 }, payload => {
   console.log('New order received', payload)
 })
 .subscribe()

Operational Limitations

Database changes are processed on a single thread to maintain the change order. That means compute upgrades don't have a large effect on the performance of Postgres change subscriptions [5], creating throughput ceilings that vertical scaling cannot address.

Enterprise Solution: Stacksync for Production CDC

While Supabase provides multiple CDC mechanisms, production environments requiring guaranteed delivery, enterprise security, and operational reliability need purpose-built solutions. Stacksync addresses these enterprise requirements through:

Guaranteed Delivery Architecture

Unlike Supabase's at-most-once webhook delivery, Stacksync provides exactly-once processing with automatic retry mechanisms, ensuring critical business events never get lost. This eliminates the operational risk of silent failures that plague native webhook implementations.

Bi-Directional Synchronization

Stacksync enables true bi-directional sync between Supabase and target systems, maintaining data consistency across your entire technology stack. This surpasses Realtime's broadcast model and webhook's one-way communication patterns.

Enterprise Security and Compliance

With SOC 2 Type II, GDPR, HIPAA BAA, and ISO 27001 certifications, Stacksync meets enterprise security requirements often needed for production Supabase deployments handling sensitive operational data.

Operational Excellence

Stacksync provides comprehensive monitoring, alerting, and error recovery capabilities that eliminate the operational overhead of managing custom CDC implementations. Teams can focus on business logic rather than maintaining integration infrastructure.

Choosing Your CDC Strategy

Database Triggers excel for maintaining referential integrity and derived table consistency within your Supabase database, providing transactional guarantees for critical data relationships.

Database Webhooks work well for fire-and-forget notifications and low-stakes external integrations where occasional message loss is acceptable.

Realtime Subscriptions enable reactive frontend experiences and collaborative features, though scaling limitations require careful subscriber management.

Enterprise-Grade Solutions like Stacksync provide production-ready CDC capabilities with guaranteed delivery, comprehensive error handling, and operational monitoring for mission-critical data synchronization requirements.

For organizations operating Supabase in production environments where data consistency and operational reliability are non-negotiable, purpose-built integration platforms deliver the enterprise-grade capabilities that native CDC approaches cannot match.

Ready to eliminate the complexity of managing custom CDC implementations? Explore Stacksync's enterprise data synchronization platform to power reliable, bi-directional sync across your entire technology stack.