The activity count is an accurate row count most of the time; however, under certain conditions the actual row count can differ from the activity count.
There is feature request (JDBC RFC 121720) for the Teradata JDBC Driver to make the activity count available to an application. We haven't scheduled work on JDBC RFC 121720 yet.
If and when we implement JDBC RFC 121720, it would be a bad idea for an application to expect the activity count to exactly match the actual row count in all cases. Instead, the application should treat the activity count as an approximate row count.
Beginning with Teradata Database 14.10 and Teradata JDBC Driver 14.00.00.25, for row count values received from the Teradata Database that are too large to fit into a signed 32-bit integer, the Teradata JDBC Driver will return an update count of Integer.MAX_VALUE to the application, and will provide a SQLWarning with error code 1474 that lists the actual row count in the message text.
For more information, please refer to the relevant section of the Teradata JDBC Driver User Guide: