i have setup postgres to postgres replication using xmin method and my replication strategy is incremental append now i want to swtich from to cdc method what will happen to existing tables ?

To switch from the xmin replication method to CDC (Change Data Capture) for your Postgres to Postgres replication, you'll need to make some changes to your setup. Here's what you need to know about the impact on existing tables: 1. CDC Setup: You'll need to set up CDC on your source Postgres database. This involves creating a publication and setting replication identities for the tables you want to replicate. For each table, you'll need to run:

sql    ALTER TABLE tbl1 REPLICA IDENTITY DEFAULT;    CREATE PUBLICATION airbyte_publication FOR TABLE tbl1, tbl2, tbl3;

[Documentation on CDC setup](https://docs.airbyte.com/integrations/sources/postgres#step-5-create-publication-and-replication-identities-for-each-postgres-table) 2. Sync Mode: Your current sync mode is "Incremental | Append". When switching to CDC, you should keep this sync mode to take full advantage of CDC. This will ensure that only changed rows are synced to the destination. [Airbyte CDC tutorial](https://airbyte.com/tutorials/postgresql-change-data-capture-elt#step-5) 3. Existing Data: When you switch to CDC, Airbyte will need to perform a full refresh of the existing tables to establish a new baseline. This is because CDC tracks changes from a specific point in time, and Airbyte needs to ensure it has the most up-to-date data before starting to track changes. 4. Resetting Existing Tables: Unfortunately, as of now, when you add a new replication method or make significant changes to an existing connection, Airbyte requires you to reset all existing tables. This means your existing destination tables will be cleared and re-synced from the beginning. [Forum discussion on adding new tables to CDC](https://discuss.airbyte.io/t/963) 5. Data Consistency: After the initial full refresh, CDC will provide a more accurate representation of your source data, including intermediate changes and deletions, which the xmin method cannot capture. [CDC vs other replication modes](https://airbyte.com/tutorials/incremental-change-data-capture-cdc-replication) In summary, switching from xmin to CDC will require you to reset and re-sync your existing tables, but it will provide more comprehensive change tracking for your data going forward. Make sure to plan for downtime or data unavailability during the switch and initial sync process.

@kapa.ai this mean that all the existing data will be removed ?

Based on the context provided, it seems you're asking about data removal in Airbyte. Yes, in certain scenarios, existing data can be removed. Let me explain: 1. When using the "Clear" functionality: Clearing data in Airbyte will remove all records from your destination tables (or files). However, the tables or files themselves are not deleted, just emptied [Clearing your data](https://docs.airbyte.com/operator-guides/clear#clear-behavior). 2. For the "overwrite" sync mode: This mode replaces whatever data exists in the destination data store with the data that arrives in the current sync [Destination Sync Modes](https://docs.airbyte.com/understanding-airbyte/airbyte-protocol#destination-sync-modes). 3. For full refresh syncs: In some destinations, like certified database and data warehouse destinations, the final table is recreated each sync. This involves writing to a temporary table during the sync, then dropping the old "final" table and renaming the new one [Destination-specific mechanism for full refresh](https://docs.airbyte.com/using-airbyte/core-concepts/sync-modes/full-refresh-overwrite-deduped#destination-specific-mechanism-for-full-refresh). It's important to note that the exact behavior can vary depending on the specific sync mode, destination, and configuration you're using. If you're concerned about data loss, make sure to review your sync settings carefully and consider backing up your data before making significant changes.

@kapa.ai my question is that when i switch from xmin method from cdc what will happen to the data in existing tables will that data be removed ?

A message from kapa.ai

To answer your question about switching from xmin replication method to CDC (Change Data Capture) in Airbyte, I'll need to clarify a few points: 1. Switching replication methods itself does not automatically remove or delete data from your existing destination tables. 2. However, when you switch replication methods, you're essentially changing how Airbyte reads and syncs data from your source. This change might affect how subsequent syncs behave. 3. CDC and xmin are different replication methods: - Xmin is a cursor-less replication method that tracks inserts and updates using the xmin system column [Postgres Replication Methods](https://docs.airbyte.com/integrations/sources/postgres#xmin). - CDC uses logical replication of the Postgres write-ahead log (WAL) to capture changes, including deletions [Postgres Replication Methods](https://docs.airbyte.com/integrations/sources/postgres#cdc). 4. When switching to CDC, you might need to perform an initial sync to ensure all data is captured correctly. This initial sync behavior depends on your specific configuration and the state of your data. 5. CDC has the advantage of capturing deletions, which xmin does not. As noted in the tutorial: "This is one of the reasons why CDC replication is often preferred." [Explore Airbyte's Change Data Capture (CDC) synchronization](https://airbyte.com/tutorials/incremental-change-data-capture-cdc-replication) To ensure data integrity when switching replication methods, I recommend: 1. Backing up your destination data before making the switch. 2. Carefully reviewing and adjusting your sync settings after switching to CDC. 3. Monitoring the first few syncs after the switch to ensure data is being replicated as expected. If you're concerned about potential data loss or have specific requirements, it might be best to consult with Airbyte's documentation or support for guidance tailored to your exact setup and use case.