reverse key meaning in Chinese

反向键, 换向键

Reverse key index cannot be used for range scan
回复：建了反向索引，为什么系统不使用索引了？
Current reversing key
电流换向开关
In a quick test on a table with 100 , 000 rows loaded using a sequence , a normal index was used for most queries returning up to 30 rows , as was the reverse key index , however , when the number of rows went up to 1 , 000 , 000 the reverse key index was never used and a full table scan was used every time
在一个用一个序列载入并含100 , 000行的表上做一个快速的测试，分别用普通索引和逆序索引查询并返回30行数据，当行数增长到1 , 000 , 000 ，将不再使用逆序索引而是每次使用全表扫描。