Sqlalchemy Why does order_by return different data and expectations when used with paging operations?

whether you use slice or limit/offset to do paging, there will be problems as long as you sort and then paginate. Why?
there is a problem when PS: only shows that the amount of data per page is less than the total amount of data. Why?

result = session_read.query(cls).order_by(cls.guild_activity.desc()).slice((page_index - 1) * page_size, page_index * page_size).all()

result = session_read.query(cls).order_by(cls.guild_activity.desc()).offset((page_index - 1) * page_size).limit(page_size).all()

Sqlalchemy python mysql

Dec.29,2021

I encountered exactly the same problem that has now been solved. The cause of this problem is not caused by sqlalchemy, you can set SQLALCHEMY_ECHO = True to analyze the SQL statement to know that there is no problem. The database I use is the sort of mysql,mysql that will cause the above problem if your sort column has many of the same values. Specific reasons can be found in this article, thanks to the great god of this article. https://www.jianshu.com/p/1e8.

because the primary key is not used

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Sqlalchemy python mysql

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