"TIME values may range from '-838:59:59' to '838:59:59'". Oooh Kaaay… that’s an oddly specific range, but I’m sure there has to be a technical reason for it. 839 hours is 34.958(3) days, and the whole range spans exactly 6040798 seconds.
NO leap second will be introduced at the end of December 2020. The difference between Coordinated Universal Time UTC and the International Atomic Time TAI is : from 2017 January 1, 0h UTC, until further notice : UTC-TAI = -37 s