要设置大小适当的目录缓存器、包缓存器和日志缓冲区以提高性能。
Set the catalog cache, package cache, and log buffer size to an appropriate size to improve performance.
当开发人员从事一个新的应用程序时，会碰到很多可配置的设置：超时设定，缓冲区大小，等等。
When developers embark on a new application, there are a great many configurable Settings they may encounter: timeouts, buffer sizes, and so forth.
这个参数设置用于 map 端排序的缓冲区大小，单位是 MB，默认值是 100。
This parameter sets the buffer size for map-side sorting, in units of MB, 100 by default.
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