@kapa.aiif I have multiple sources defined in airbyte (say all pg sources) all pointing to the same Pg source. and lets say im doign CDC style streaming. does it make sense to have multiple source isntances in airbyte for the same source, like some perf benifitis of sorts? or is the same as, one source isntance and multiple conections ?

Yes, it does make sense to have multiple source instances in Airbyte for the same source when doing CDC style streaming. This can help with performance and parallelization. For example, if you have a Postgres database with a few large tables and hundreds of smaller ones, you could set up separate connections (CDC) for one connection per big table and one connection for all the remaining small tables. This could potentially improve performance and parallelization [source](https://discuss.airbyte.io/t/1863). However, it's important to note that Airbyte requires a replication slot configured only for its use. Only one source should be configured that uses this replication slot. To create a replication slot, you can use the pgoutput plugin and run the following command as the user with the newly granted

REPLICATION

role:

sql SELECT pg_create_logical_replication_slot('airbyte_slot', 'pgoutput');

The output of this command will include the name of the replication slot to fill into the Airbyte source setup page [source](https://docs.airbyte.com/integrations/sources/postgres#step-4-create-a-replication-slot-on-your-postgres-database). When setting up the source and destination in Airbyte, you can instantiate a Postgres source connector and a Postgres destination connector [source](https://airbyte.com/tutorials/incremental-change-data-capture-cdc-replication). If you're upgrading to Destinations V2, you can optionally dual write, but this requires resyncing historical data from the source. You must create a new Postgres source with a different replication slot than your existing source to preserve the integrity of your existing connection [source](https://docs.airbyte.com/release_notes/upgrading_to_destinations_v2#upgrade-paths-for-connections-using-cdc).

@kapa.ai cant i still do the same with one source, but multipe connections each pointing to a different replication slot?

A message from kapa.ai

Yes, you can indeed have one source with multiple connections, each pointing to a different replication slot. This approach allows you to handle different data streams separately, which can be beneficial for performance and parallelization. However, it's important to note that each replication slot should be used by only one source. This is because a replication slot in Postgres is a stream of database changes that can be consumed by only one client at a time. If multiple sources try to consume from the same replication slot, it could lead to data inconsistencies. To create multiple replication slots, you can run the

pg_create_logical_replication_slot

command multiple times, each time with a different slot name. For example:

sql SELECT pg_create_logical_replication_slot('airbyte_slot1', 'pgoutput');   SELECT pg_create_logical_replication_slot('airbyte_slot2', 'pgoutput');

Each command will return the name of the replication slot, which you can then use to set up a separate connection in Airbyte [source](https://docs.airbyte.com/integrations/sources/postgres#step-4-create-a-replication-slot-on-your-postgres-database).

can one unique source be attached to one replication slot only? @kapa.ai

A message from kapa.ai

Yes, in the context of Airbyte and Postgres, one unique source should be attached to one replication slot only. This is because a replication slot in Postgres is a stream of database changes that can be consumed by only one client at a time. If multiple sources try to consume from the same replication slot, it could lead to data inconsistencies. Airbyte requires a replication slot configured only for its use. Only one source should be configured that uses this replication slot. This is due to how Postgres CDC is implemented - each destination would receive only part of the data available in the replication slot [source](https://docs.airbyte.com/integrations/sources/postgres/postgres-troubleshooting#cdc-requirements). To create a replication slot, you can use the

pg_create_logical_replication_slot

command with the

pgoutput

plugin:

sql SELECT pg_create_logical_replication_slot('airbyte_slot', 'pgoutput');

The output of this command will include the name of the replication slot to fill into the Airbyte source setup page [source](https://docs.airbyte.com/integrations/sources/postgres#step-4-create-a-replication-slot-on-your-postgres-database).

can i have one source be mapped to multiple replicaton slots @kapa.ai?

A message from kapa.ai

No, in Airbyte, one source should not be mapped to multiple replication slots. Each source in Airbyte should be associated with a unique replication slot. This is because a replication slot in Postgres is a stream of database changes that can be consumed by only one client at a time. If a single source tries to consume from multiple replication slots, it could lead to data inconsistencies. When setting up a source in Airbyte, you specify the replication slot that the source should use. This replication slot is then used exclusively by that source for Change Data Capture (CDC). Here's how you can create a replication slot:

sql SELECT pg_create_logical_replication_slot('airbyte_slot', 'pgoutput');

The output of this command will include the name of the replication slot to fill into the Airbyte source setup page [source](https://docs.airbyte.com/integrations/sources/postgres#step-4-create-a-replication-slot-on-your-postgres-database). If you want to consume data from multiple replication slots, you should set up multiple sources in Airbyte, each associated with a different replication slot.