ALTER TABLE segment_collections ADD COLUMN ns TEXT;
UPDATE segment_collections SET ns = CASE
  WHEN instr(substr(nsid, instr(nsid, '.') + 1), '.') = 0 THEN nsid
  ELSE substr(nsid, 1, instr(nsid, '.') + instr(substr(nsid, instr(nsid, '.') + 1), '.') - 1)
END WHERE ns IS NULL;
CREATE INDEX IF NOT EXISTS segment_collections_ns ON segment_collections (ns, idx);