full table scan
英汉例句
- The predicates in the query in Listing 7 are weakly selective so that a full table scan of the pdbxml table is required.
清单 7 中查询的谓词选择性较弱，因此需要对 pdbxml 表进行全表扫描。 - Most often, you want only a small subset of the data in the table, so a full table scan wastes a lot of disk I/O and therefore time.
通常来说，您可能只希望获得表中数据的一个子集，因此全表扫描会浪费大量的磁盘 I/O，因此也就会浪费大量时间。 - If there is no index on ucname, the DBMS still does a full table scan, but it need not do any further processing on the data to determine whether or not it satisfies the query.
如果没有为 ucname 创建索引，DBMS 仍然执行全表扫描，但是不会对数据进行进一步处理来判断其是否满足查询。