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我加入了多个表,总行数约为 250 亿。最重要的是,我正在做聚合。这是我的配置单元设置,如下所示,我用它来生成最终输出。我不确定如何调整查询并使其运行得更快。目前,我正在反复试验,看看是否能产生一些结果,但这似乎不起作用。映射器运行得更快,但减速器需要永远完成。有人可以分享您对此的想法吗?谢谢你。

    SET hive.execution.engine=tez;
    SET hive.exec.dynamic.partition.mode=nonstrict;
    SET hive.qubole.cleanup.partial.data.on.failure=true;
    SET hive.tez.container.size=8192;
    SET tez.task.resource.memory.mb=8192;
    SET tez.task.resource.cpu.vcores=2;
    SET hive.mapred.mode=nonstrict;
    SET hive.qubole.dynpart.use.prefix=true;
    SET hive.vectorized.execution.enabled=true;
    SET hive.vectorized.execution.reduce.enabled =true;
    SET hive.cbo.enable=true;
    SET hive.compute.query.using.stats=true;
    SET hive.stats.fetch.column.stats=true;
    SET hive.stats.fetch.partition.stats=true;
    SET mapred.reduce.tasks = -1;
    SET hive.auto.convert.join.noconditionaltask.size=2730;
    SET hive.auto.convert.join=true;
    SET hive.auto.convert.join.noconditionaltask=true;
    SET hive.auto.convert.join.noconditionaltask.size=8053063680;
    SET hive.compute.query.using.stats=true;
    SET hive.stats.fetch.column.stats=true;
    SET hive.stats.fetch.partition.stats=true;
    SET mapreduce.job.reduce.slowstart.completedmaps=0.8;
    set hive.tez.auto.reducer.parallelism = true;
    set hive.exec.reducers.max=100;
    set hive.exec.reducers.bytes.per.reducer=1024000000;

SQL:

SELECT D.d
      ,D.b
      ,COUNT(DISTINCT A.x)  AS cnt
      ,SUM(c)               AS sum
 FROM A
LEFT JOIN
       B
ON A.a = B.b
LEFT JOIN
       C 
ON B.b = C.c
JOIN
       D
 ON A.a >= D.d
AND A.a <= D.d
GROUP BY 1,2
CLUSTER BY D.d;
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1 回答 1

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还没有查询计划,所以也许还有别的东西,但这些设置肯定会限制减速器的并行性:

set hive.exec.reducers.max=100;
set hive.exec.reducers.bytes.per.reducer=1024000000;

我建议增加允许的减速器数量并减少每个减速器的字节数,这将增加减速器的并行度:

set hive.exec.reducers.max=5000; 
set hive.exec.reducers.bytes.per.reducer=67108864;

Hive 1.2.0+ 还为 count(distinct) 提供了自动重写优化。检查这个设置,它应该是true默认的:

hive.optimize.distinct.rewrite=true;

如果查询停留在最后一个 reducer 上,则连接键存在偏差

于 2019-02-02T08:28:59.193 回答