Sorting is required when no index satisfies the requested ordering of fetched rows, or the optimizer determines that a sort is less expensive than an index scan.
如果没有索引满足所取的行的要求顺序，或者优化器断定排序的代价低于索引扫描，那么就需要进行排序。
Typically, a non-matching index scan is chosen by the optimizer when the underlying index provides benefits such as index-only access, avoids sort, or some similar benefit.
通常情况下，在基础索引提供好处(如唯一索引访问、避免排序或一些类似的好处)时，可通过优化器选择非匹配索引扫描。
Therefore, when deciding which join method to choose, the optimizer balances the sort cost and the performance benefit for the inner table scan to drive the decision.
因此，在决定选择哪种联接方法时，优化器为内部表扫描平衡排序成本和性能优势以便促进决策。
But another machine in the plant, which USES a laser to scan the passing material, can sort plastic by type and colour with great accuracy.
但是工厂里的另一套设备则不一样了。其利用激光对经过的材料进行扫描，按照塑料的种类和颜色进行分类，且准确率极高。
Merge scan join (MSJOIN) with sort for outer and inner
使用内部和外部排序的合并扫描联接 (MSJOIN)
For instance, the purchaseOrders table is partitioned by po_date and has a local index on po_customer, the query below will need a sort after the index scan.
例如，表purchaseorders通过po_date进行了分区，并具有本地索引po_customer，以下查询在完成索引扫描后还需要进行排序。
Sort through a pile of paper that's been building up for the past few weeks. Recycle or scan – try to get it down to less than half.
把上几周的文件分类整理好。循环再利用一些——最好收拾到不到一半的数量。
Compared with the scan line algorithm, it has a simple data structure, no need to maintain and sort lots of tables, simple implementation, and fitting for being implemented by hardware.
该算法和扫描线算法相比，具有数据结构简单，不需要对众多的表格进行维护和排序，实现思想简洁和适合硬化等优点。
So the choice of which sort of scan is used depends on which type of cancer is suspected or being investigated.
所以，具体选择哪种方式扫描取决于怀疑是哪种癌症或研究哪种癌症。
Shoppers scan check reviews and recommendations on the Internet before they make theirdecisions, without having someone sort of breathing down their necks.
购物者在做决定之前，可以在网上查看评论和推荐，而不会有人紧盯着自己。
Its core function can make a enterprise to scan, inquire, sort and count the permanent information resource stored in database.
提供的核心功能使企业能够对存储在数据库中的永久信息资源进行搜索、查询、分类、统计。
Its core function can make a enterprise to scan, inquire, sort and count the permanent information resource stored in database.
提供的核心功能使企业能够对存储在数据库中的永久信息资源进行搜索、查询、分类、统计。
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