Need Detailed to build real time CDC Data Pipeline

Hi Team,

We have use case to build a real time data pipeline from PostgresSQL to sync data with other DB. We have created logical slots to read WAL logs.
We are exploting some markets tools as well like ‘Debezium’, still want to have one option without relying on any other open source tool.

We came across 2 functions :

1. ‘pg_logical_slot_get_changes’ function will give us all the slot changes from previous read point, but once we read it the changed will be deleted from the slot.
2. ‘pg_logical_slot_peek_changes’ will give us the changes from previous read point, but it will not delete it.

Questions :
#1. How can we guarantee that once changes read and we update them into desired database, we would still have a place to have the WAL logs to read again if anything goes wrong while processing ?

#2. Also ther are parameters in ‘pg_logical_slot_get_changes’ , unable to find the examples to use the ‘upto_lsn,and ‘upto_nchanges’ and ‘VARIADIC options text[]’. Some examples and usecases to support it will be helpful for us.

* Reference : https://pgpedia.info/p/pg_logical_slot_get_changes.html

- pg_logical_slot_get_changes ( slot_name name, upto_lsn pg_lsn, upto_nchanges integer, VARIADIC options text[] ) →
setof record ( lsn pg_lsn, xid xid, data text )

Appreciate your early response.

Regards,
Puja Ajmera

INTERNAL

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