Teradata Database invokes a constant mode table function repeatedly, allowing the function to pass through different phases where it can perform initialization, connect to external objects, build output rows, close open connections, and clean up. The function uses the FNC_GetPhase library function to determine the phase in which it was called and what action to take.
Here are the phases that the function passes through:
For more information on implementing each phase of a constant mode table function, see Implementation Guidelines.