问题1：数据库建索引选择的是hash，但保存后自动变成了btree数据库里会出现重复的字段是不是都不能成功建立hash索引？
问题似乎解决了，我选的innodb，不支持hash索引。那么问题2来了：大家实践后觉得mysql四种引擎都有什么要注意的？
光阴似箭催人老，日月如移越少年。
MySQL’s InnoDB and MyISAM engines do not support Hash indexes. Only NDB supports hash indexes. I don’t know which engine you chose?
Unless you have special needs, generally choose the innodb engine
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MySQL’s InnoDB and MyISAM engines do not support Hash indexes. Only NDB supports hash indexes. I don’t know which engine you chose?
Unless you have special needs, generally choose the innodb engine