In order to change the average load for a reducer (in bytes): set hive.exec.reducers.bytes.per.reducer=<number> In order to limit the maximum number of reducers: set hive.exec.reducers.max=<number> In order to set a constant number of reducers: set mapreduce.job.reduces=<number>

你的问题是关于在Hive中如何控制reducer数量的设置。为了改变reducer的平均负载（以字节为单位），可以使用以下命令：set hive.exec.reducers.bytes.per.reducer=<number>。如果想要限制reducer的最大数量，可以使用命令：set hive.exec.reducers.max=<number>。如果想要设置常数数量的reducer，可以使用命令：set mapreduce.job.reduces=<number>。

相关问题

set hive.exec.reducers .bytesper.reducer=<number>

The configuration parameter `hive.exec.reducers.bytes.per.reducer` is used to set the number of bytes of input data processed by a single reducer. This parameter is used to control the number of reducers required to process a particular job.

To set this parameter, you need to use the following syntax:

set hive.exec.reducers.bytes.per.reducer=<number>;

where `<number>` is the number of bytes of input data that should be processed by a single reducer. For example, if you want to set the number of bytes to 256 MB, you can use the following command:

set hive.exec.reducers.bytes.per.reducer=268435456;

Note that this parameter is only used when the number of reducers is not explicitly set for a particular job. If the number of reducers is set explicitly, then this parameter is ignored.

load data inpath '/ss.txt' into table stu_buck; Query ID = root_20230607152813_9b23ac0d-4120-4267-b5ec-a6cb0eaf0988 Total jobs = 2 Launching Job 1 out of 2 Number of reduce tasks determined at compile time: 4 In order to change the average load for a reducer (in bytes): set hive.exec.reducers.bytes.per.reducer=<number> In order to limit the maximum number of reducers: set hive.exec.reducers.max=<number> In order to set a constant number of reducers: set mapreduce.job.reduces=<number> Cannot run job locally: Number of reducers (= 4) is more than 1 Starting Job = job_1686122831321_0001, Tracking URL = http://hadoop100:8088/proxy/application_1686122831321_0001/ Kill Command = /opt/module/hadoop-3.1.3/bin/mapred job -kill job_1686122831321_0001

这段代码是在将数据文件 `/ss.txt` 加载到 Hive 表 `stu_buck` 中。其中的警告信息是关于 MapReduce 任务的配置，告诉你当前任务需要启动一个 Map 任务和四个 Reduce 任务，但是由于这里是本地模式，所以不能运行。它会启动一个 MapReduce 作业，并提供作业 ID 和跟踪 URL，同时还提供了一个 kill 命令，以便你可以在需要的时候终止作业。