code: func GetOrdinalOfRangeCond(sc *stmtctx.StatementContext, ran *ranger.Range) int {
  	for i := range ran.LowVal {
  		a, b := ran.LowVal[i], ran.HighVal[i]
  		cmp, err := a.CompareDatum(sc, &b)
  		if err != nil {
  			return 0
  		}
  		if cmp != 0 {
  			return i
  		}
  	}
  	return len(ran.LowVal)
  }
docs: // GetOrdinalOfRangeCond gets the ordinal of the position range condition,
  // if not exist, it returns the end position.