When Oracle retrieves data from a non-Oracle system, the Heterogeneous Services initialization parameter, HS_RPC_FETCH_SIZE, defines the number of bytes sent for each fetch between the agent and Oracle Database. The agent fetches data from the non-Oracle system until one of the following occurs:
It has accumulated the specified number of bytes to send back to Oracle Database.
The last row of the result set is fetched from the non-Oracle system.