计算表中的行 [英] Count rows in table

问题描述

我对Cassandra DB中非常大的表的行计数感到麻烦。

I have a trouble with the rows counting of very huge table in Cassandra DB.

简单的语句：

SELECT COUNT(*) FROM my.table;

调用超时错误：

OperationTimedOut: errors={}, ...

我增加了在〜/ .cassandra / cqlshrc文件中的client_timeout：

I have increased client_timeout in ~/.cassandra/cqlshrc file:

[connection]
client_timeout = 900

语句这次正在运行，并再次调用OperationTimeout错误。我该如何计数表中的行？

Statement is running this time and invokes OperationTimeout error again. How can I count rows in table?

推荐答案

您可以通过使用拆分标记范围来多次计数。
Cassandra使用的令牌范围是-2 ^ 63至+ 2 ^ 63-1。因此，通过拆分此范围，您可以执行以下查询：

You could count multiple times by using split token ranges. Cassandra uses a token range from -2^63 to +2^63-1. So by splitting up this range you could do queries like that:

select count(*) from my.table where token(partitionKey) > -9223372036854775808 and token(partitionKey) < 0;
select count(*) from my.table where token(partitionKey) >= 0 and token(partitionKey) < 9223372036854775807;

将这两个计数相加，便得到总数。
如果仍然无法通过这些查询，则可以再次将其拆分为较小的令牌范围。

Add those two counts and you'll have the total count. If those querys still not go through you can split them again into smaller token ranges.

请查看此工具，该工具的作用基本上是这样的： https://github.com/brianmhess/cassandra-count

Check out this tool, which does basically exactly that: https://github.com/brianmhess/cassandra-count

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