Prerequisites

• Connection details
• Streamkap user and role

Granting Privileges

It's recommended to create a separate user and role for Streamkap to access your PostgreSQL database. Below is an example script that does that.

-- Connect to the PostgreSQL server as admin

-- Create the Streamkap User
CREATE USER STREAMKAP_USER WITH PASSWORD 'user_password';

-- Create the Streamkap schema and grant privileges
CREATE SCHEMA STREAMKAP;
GRANT USAGE, CREATE ON SCHEMA STREAMKAP TO STREAMKAP_USER;

-- Grant specific privileges on tables within the schema
GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA STREAMKAP TO STREAMKAP_USER;

Streamkap Setup

1. Go to Destinations and choose PostgreSQL

2. Input the following information:

   • Name - A unique and memorable name for this Connector
   • Hostname - The hostname connection string without the port.
   • Port - The port number of the connection
   • Username (Case sensitive) - STREAMKAP_USER OR the username you chose
   • Password - The password for your username
   • Database Name (Case sensitive) - STREAMKAPDB OR the database name you chose
   • Schema Name (Case sensitive) - STREAMKAP OR the schema name you chose
   • Insert Mode Insert or Upserts (i.e. append only or replace)
   • Delete Mode - Delete records in destination if deleted at source
   • Schema Evolution - Handle additional columns automatically?
   • Tasks - Amount of parallelism in writing events.

3. Click Save

How this Connector Works

The PostgreSQL connector supports idempotent write operations by using upsert semantics and basic schema evolution.

The following features are supported:

• At-least-once delivery
• Delete mode
• Idempotent writes (Insert/Upsert mode)
• Schema evolution

At-least-once delivery

The PostgreSQL connector guarantees that events that is consumes are processed at least once.

Delete mode

The PostreSQL connector can delete rows in the destination database when a DELETE or tombstone event is consumed.

Idempotent writes

The PostgreSQL connector supports idempotent writes, allowing the same records to be replayed repeatedly and the final database state to remain consistent. In order to support idempotent writes, the PostgreSQL connector must be set to Upsert mode. An upsert operation is applied as either an update or an insert, depending on whether the specified primary key already exists. If the primary key value already exists, the operation updates values in the row. If the specified primary key value doesn’t exist, an insert adds a new row.

Schema evolution

The PostgreSQL connector supports schema evolution

The connector automatically detects fields that are in the event payload but that do not exist in the destination table. The connector alters the destination table to add the new fields.

When schema evolution is set to Yes, the connector automatically creates or alters the destination database table according to the structure of the incoming event.

When an event is received from a topic for the first time, and the destination table does not yet exist, the PostgreSQL connector uses the event’s key, or the schema structure of the record to resolve the column structure of the table. If schema evolution is enabled, the connector prepares and executes a CREATE TABLE SQL statement before it applies the DML event to the destination table.

When the PostgreSQL connector receives an event from a topic, if the schema structure of the record differs from the schema structure of the destination table, the connector uses either the event’s key or its schema structure to identify which columns are new, and must be added to the database table. If schema evolution is enabled, the connector prepares and executes an ALTER TABLE SQL statement before it applies the DML event to the destination table. Because changing column data types, dropping columns, and adjusting primary keys can be considered dangerous operations, the connector is prohibited from performing these operations.