There is xmin parameter in replication slot.I saw this value is empty in case of logical replication.From this it is clear that logical slots does not help in preventing vacuum process of dead tuples required by select queries on standby.
Is my understanding correct?
Logical replication slots have
catalog_xmin, because logical decoding needs to be able to access old, deleted information from the catalog tables. For example, if you truncated or renamed a table, and logical decoding has to process a WAL record from before the truncation or renaming, it still has to be able to access the state of the catalog as it was when the WAL record was written.catalog_xminwill hold backVACUUMprogress just as well asxmin.