Common Postgres Source Setup Mistakes

May 2026

PostgreSQL source setup usually breaks when teams validate SQL connectivity but skip the logical replication prerequisites behind CDC.

Short Answer

The most common PostgreSQL source mistakes are relying on generic SQL connectivity tests, leaving table scope implicit, and enabling CDC without checking logical replication settings. Skippr can read PostgreSQL tables directly with host, port, user, password, and database settings or a connection string, but CDC depends on wal_level = logical, a replication-capable user, and available replication slots.

That split is important because the first SELECT can work while the CDC design is still incomplete. Teams often discover this when the application user can read tables but lacks the REPLICATION attribute, or when the server has not been configured to allow logical replication at all. Another recurring issue is treating restarts like generic reconnects even though Skippr resumes from a stored committed LSN and expects the replication slot to retain the necessary WAL.

Why Teams Struggle with This

PostgreSQL setup mistakes usually come from collapsing three concerns into one mental model: ordinary SQL access, table selection, and logical replication. The source docs and CDC docs separate those concerns because the operational requirements are different even if the hostname is the same.

• A user that can read tables is not automatically a user that can run CDC through logical replication.
• CDC requires wal_level = logical and enough replication slots, which are server settings rather than connector toggles.
• If the team never decides which tables or queries belong in the source, the first extract is harder to validate.
• Resume depends on the stored committed LSN and on the replication slot retaining WAL across downtime.

How Skippr Handles It

Skippr makes the PostgreSQL source contract explicit by separating the batch connector surface from the CDC-specific replication configuration. You can review host, port, database, and table scope, then independently review whether cdc_enabled, the replication slot, and publication settings are actually viable.

That helps teams avoid a common trap: treating CDC as a downstream warehouse concern. In practice, the source setup decides whether inserts, updates, and deletes can be captured with full after images and resumed safely after interruptions.

• Direct PostgreSQL source configuration for host, port, user, password, database, and optional table scope.
• CDC via WAL logical replication using pgoutput.
• Durable resume behavior based on stored committed LSN values.
• Reuse of replication slots across restarts so source ordering stays consistent.

What the First Useful Version Looks Like

A strong first version is one readable database connection and one short table list that proves the source is scoped correctly.

If logical replication is part of the plan, review wal_level, replication rights, and slot availability before expanding the pipeline, because those source guarantees are harder to retrofit under pressure.