Cassandra cqlsh查询失败，没有错误 [英] Cassandra cqlsh query fails with no error

问题描述

我一直试图运行这样的查询：

I have been trying to run a query like this:

SELECT COUNT(*) FROM sensors WHERE sensor_id = 1 and date = '2014-11';

WHERE子句过滤到具有大约200万列的分区键。我希望得到约计数结果。 2百万，但是我得到这个错误：

on a column family. The WHERE clause filters down to a partition key with around 2 million columns. I expect to get a count result of approx. 2 million, but instead I get this error:

errors={}, last_host=[THE_IP_OF_MY_SERVER]

如果我运行查询以获取列，它返回的数据很好，但它不能返回计数。我了解此类计数查询可能遇到的性能问题（例如此处），但我仍然想为这个查询获得一些结果进行测试。

if I run the query to get the columns it returns the data just fine, but it cannot return the count. I understand the performance issues such count query might have (for example the ones discussed here) but I still would like to get some result for this query for my tests.

所以我的问题是：

1. 这是超时错误吗？如果是，我可以如何增加超时时间？


2. 如果没有，为什么我得到这个错误？有没有办法获得更多的细节？

我使用的是Cassandra 2.1，

I am using Cassandra 2.1 with cqlsh 5.0.1 and spec 3.2 on a cluster of two nodes both running Ubuntu 14.04.

感谢

推荐答案

它应该是一个超时。如果计划使用范围查询，可以通过更改read_request_timeout_in_ms或甚至range_request_timeout_in_ms（在cassandra.yaml中）的值来增加请求所需的最长时间。

It should be a timeout. You can increase the maximum time needed for the request by changing the value of "read_request_timeout_in_ms" or even "range_request_timeout_in_ms" (in cassandra.yaml) if you plan to use range queries. Restart the cluster after changing the values (they default to 10 seconds).

请注意，如果对分区键运行完全查询，您将获得0或1作为计数。因此，如果返回多于1行，那么您的查询是对聚类列（主键的第一列之后的列）。

Note that if you run exact queries on partition keys you will get 0 or 1 as count. So your query is on clustering columns (the ones after the first column of primary key) if it returns more than 1 row.

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