Cassandra 的 0.7 二级索引是如何存储的? [英] How are Cassandra's 0.7 Secondary Indexes stored?

问题描述

我们一直在使用 Cassandra 0.6，现在有数百万个键的列族.我们有兴趣使用 0.7 中可用的新二级索引功能，但找不到有关如何存储新索引的任何文档.

We have been using Cassandra 0.6 and now have Column Families with millions of keys. We are interested in using the new Secondary Index feature available in the 0.7 but couldn't find any documentation on how the new index is stored.

是否有任何磁盘空间限制，或者索引的存储方式是否与键类似，因为它分布在多个节点上?

Is there any disk-space limitation or is the index stored similar to keys in that it's spread over multiple nodes?

我曾尝试通过 Cassandra 网站寻找答案，但无济于事.

I've tried combing through the Cassandra site for an answer but to no avail.

推荐答案

二级索引存储为用户无法访问的列族.它们的大小大致为:

Secondary indexes are stored as Column Families that are not accessible by the user. Their size will roughly be:

(索引值集的基数 * 索引值的平均大小)+(索引列族中的键数 * 列族中键的平均大小).

(cardinality of the set of indexed values * the avg size of the index values) + (the number of keys in the indexed column family * the avg size of keys in the column family).

节点只索引本地存储的行——也就是说，只索引它们作为副本的行.

Nodes only index rows that are stored locally -- that is, only rows for which they are a replica.

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