code: protected Map<String, String> getTableComments(DatabaseConfig config) throws SQLException {
          Map<String, String> answer = new HashMap<String, String>();
          try {
              PreparedStatement preparedStatement = dbMetadataUtils.getConnection().prepareStatement("select tname,comments from(select relname as TNAME ,col_description(c.oid, 0) as COMMENTS from pg_class c where  relkind = 'r' and relname not like 'pg_%' and relname not like 'sql_%') as temp where comments is not null ");
              ResultSet rs = preparedStatement.executeQuery();
              while (rs.next()) {
                  answer.put(rs.getString(dbMetadataUtils.convertLetterByCase("tname")), rs.getString(dbMetadataUtils.convertLetterByCase("comments")));
              }
              closeResultSet(rs);
          } catch (Exception e) {
              throw new RuntimeException(e);
          }
          return answer;
      }
docs: 获取表名和注释映射
  
  @param config
  @return
  @throws java.sql.SQLException