code: func DetachSimpleCondAndBuildRangeForIndex(sctx sessionctx.Context, conditions []expression.Expression,
  	cols []*expression.Column, lengths []int) ([]*Range, []expression.Expression, error) {
  	newTpSlice := make([]*types.FieldType, 0, len(cols))
  	for _, col := range cols {
  		newTpSlice = append(newTpSlice, newFieldType(col.RetType))
  	}
  	res, err := detachCNFCondAndBuildRangeForIndex(sctx, conditions, cols, newTpSlice, lengths, false)
  	return res.Ranges, res.AccessConds, err
  }
docs: // DetachSimpleCondAndBuildRangeForIndex will detach the index filters from table filters.
  // It will find the point query column firstly and then extract the range query column.