摘要:
问题:create table A ( id varchar(64) primary key, ver int, ...)在id,ver上有联合索引,10000条数据为什么select id from A order by id特别慢?而select id from A order by id,ve 阅读全文
摘要:
索引优化 ,b-tree假设某个表有一个联合索引(c1,c2,c3,c4) 以下 只能使用该联合索引的c1,c2,c3部分A. where c1 = x and c2 = x and c4>x and c3 = xB. where c1 = x and c2 = x and c4=x order b 阅读全文