Next, the middle HSJOIN would cause execution of SHIPs 3 and 4 in sequence, after which the join result would be delivered to the UNION.

接着，中间的HSJOIN将导致SHIP 3和SHIP 4依次执行，然后连接结果被提交给UNION。

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The UNION operator reads data from each SHIP buffer, one buffer at a time. The sequence of operations is as follows

而 UNION 操作符则从每个 SHIP 缓冲区中读取数据，每次读取一个缓冲区。

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International Telecommunications Union, ITU Recommendation Z.120: Message Sequence Chart (MSC), (04/04), ITU-T, 2004.

国际电信组织, ITU Recommendation Z.120: 消息序列图 (MSC), (04/04), ITU-T, 2004.

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