<span>java中垃圾回收机制中的引用计数法和可达性分析法（最详细）</span>

with&nbsp;a&nbsp;as(&nbsp;select&nbsp;user_id,fdate,&nbsp;cast(diff&nbsp;as&nbsp;SIGNED)&nbsp;-&nbsp;cast(sign1&nbsp;as&nbsp;SIGNED)&nbsp;as&nbsp;sign&nbsp;from(&nbsp;select&nbsp;user_id,fdate,&nbsp;datediff(fdate,'2023-01-01')&nbsp;diff,&nbsp;row_number()&nbsp;over(partition&nbsp;by&nbsp;user_id&nbsp;order&nbsp;by&nbsp;fdate&nbsp;)&nbsp;as&nbsp;sign1&nbsp;from&nbsp;tb_dau&nbsp;where&nbsp;fdate&nbsp;between&nbsp;'2023-01-01'&nbsp;and&nbsp;'...