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PostgreSQL

This article describes how to ingest CDC data from your PostgreSQL database.

Prerequisites

Ensure you have a connection to your PostgreSQL database and that it has been enabled for CDC.

For more information, please read the guide to Enable CDC on PostgreSQL.

Create a CDC job that reads from your database

You can create a job to ingest your data from PostgreSQL into a staging table in the data lake.

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Ingest to the data lake

After completing the prerequisites, you can create your staging tables. The example below creates a table without defining columns or data types, as this will be inferred automatically by Upsolver, though you can define columns if required:

CREATE TABLE default_glue_catalog.upsolver_samples.orders_raw_data()
    PARTITIONED BY $event_date;

Upsolver recommends partitioning by the system column $event_date or another date column within the data in order to optimize your query performance.

Next, you can create an ingestion job as follows:

CREATE JOB load_orders_raw_data_from_postgres
      PUBLICATION_NAME = 'sample'
AS COPY FROM POSTGRES upsolver_postgres_samples 
INTO default_glue_catalog.upsolver_samples.orders_raw_data;

Note that multiple ingestion jobs can write to the same table, resulting in a final table that contains a UNION ALL of all data copied into that table. This means that any duplicate rows that are written are not removed and the columns list may expand if new columns are detected.

This may not be your intended behavior, so ensure you are writing to the correct table before running your job.

Job options

The example above only uses a small subset of all job options available when reading from PostgreSQL. Depending on your use case, you may want to configure a different set of options.

Transformations can be applied to your ingestion job to correct issues, exclude columns, or mask data before it lands in the target. Furthermore, you can use expectations to define data quality rules on your data stream and take appropriate action.

Alter a job that reads from PostgreSQL

Some job options are considered mutable, enabling you to run a SQL command to alter an existing ingestion job rather than create a new job.

For example, take the job we created earlier:

CREATE JOB load_orders_raw_data_from_postgres
      PUBLICATION_NAME = 'sample'
AS COPY FROM POSTGRES upsolver_postgres_samples 
INTO default_glue_catalog.upsolver_samples.orders_raw_data;

If you want to keep the job as is, but only change the cluster that is running the job, execute the following command:

ALTER JOB load_orders_raw_data_from_postgres 
    SET COMPUTE_CLUSTER = my_new_cluster;

Note that some options such as COMPRESSION cannot be altered once the connection has been created.

Drop a job that reads from PostgreSQL

If you no longer need a job, you can easily drop it using the following SQL command: 

DROP JOB load_orders_raw_data_from_postgres;

Learn More

Please see the SQL command reference for PostgreSQL for full details of the available job options and further examples.

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