# Deep Paging Case Study Background (Continued...)

+ After the production went online for a while

![left](./student-guide/diagram/01-21-1.png)

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After production went live, it generally worked normally in the early days, but as the volume of t1 table data increased, there were more and more slow query, and the service stability became worse. Let's compare slow query SQL with the previous one:

(omitted)