如果一项修改的目标是减少数据库的内存占用量，那么取消各种缓冲区肯定会有帮助，但是这会牺牲查询速度和应用程序性能。
If the goal of a change is to reduce the memory footprint of the database, eliminating various buffers will certainly help, at the expense of query speed and application performance.
查询在远程服务器上的编译，以及取足够的数据来填充union所有分支上的AT Q缓冲区，这两个过程是并行进行的。
The compilation of the query on the remote server and fetching of enough data to fill the ATQ buffer on all legs of the UNION will proceed in parallel.
缓冲区被调优之后，就能够通过查询它来验证调优效果或捕捉备份中的配置，这十分有帮助。
Once they have been tuned, it is helpful to be able to inquire on them to verify the tuning or to capture the configuration in a backup.
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