当偏移量可变时，如何捕获“ ext”事件？

听起来您想要基于时间的第一个和最后一个事务。我认为以下是您想要的：

select item,       min(transaction) keep (dense_rank first order by timestamp) as StartTx,        min(transaction) keep (dense_rank last order by timestamp) as EndTx,       max(timestamp) - min(timestamp)from transactions tgroup by item;