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