n is either 1 or 0. The default value is 0.
When ECPSync is enabled (n = 1), each time a SELECT statement is executed InterSystems IRIS® data platform forces all pending Enterprise Cache Protocol (ECP) requests to the database server. On completion, this guarantees that the client cache is in sync.
ECP is a distributed data caching architecture that manages the distribution of data and locks among a heterogeneous network of server systems. For further details, refer to Queries and ECP in the “Querying the Database” chapter in Using InterSystems SQL.