Access plan directives that force the optimizer to use the designated access method for data retrieval, either sequential scan or index scan.
访问计划指示，强制优化器使用指定的访问方法进行数据检索，要么是连续扫描，要么是索引扫描。
2
The above example shows that sequential scan and indexes are used to do the data retrieval, and the nested-loop join method is used to join all tables.