-- Backup the start_time and end_time column values and convert existing
-- timestamps to microsecond precision
-- TODO(wperron): remove this before publishing
ALTER TABLE spans RENAME COLUMN start_time TO start_time_bak;
ALTER TABLE spans RENAME COLUMN end_time TO end_time;
ALTER TABLE spans ADD COLUMN (start_time INTEGER ) DEFAULT (start_time_bak * 1000);
ALTER TABLE spans ADD COLUMN (end_time INTEGER ) DEFAULT (end_time * 1000);