如果无法将排序的数据整个放入排序堆中(排序堆是每次执行排序时分配的一块内存)，它就会溢出到该数据库所有的临时表中。

If the sorted data cannot fit entirely into the sort heap, which is a block of memory that is allocated each time a sort is performed, it overflows into a temporary table owned by the database.

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溢出是指数据被添加到分配给该缓冲区的内存块之外。

An overflow occurs when data is added to the buffer outside the block of memory allocated to the buffer.

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另外，为了避免溢出，还采用块浮点结构表示数据，节省了大量的硬件资源。

Moreover, in order to avoid overflowing, it also USES block-floating-piont structure that can save many hardware resources.

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