需要 Cassandra 架构
你好 刚开始研究Cassandra，有点困惑。 您能否建议以下架构：
架构：email, city, items1[], items2[]
输入：cityId, item1, item2
我需要：
select email
where city=cityId
and item1 is NOT in items1[]
and item2 is NOT in items2[]
可以吗？
HI
Just started to investifate Cassandra and have a bit confusion.
Could you suggest schema for following:
Schema: email, city, items1[], items2[]
Input: cityId, item1, item2
I need:
select email
where city=cityId
and item1 is NOT in items1[]
and item2 is NOT in items2[]
Is it possible?
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您可能需要提供更多细节才能获得此问题的彻底答案。
在 Cassandra 0.7 及以上版本中，您可以使用二级索引根据列值选择行（即选择 city=cityId 的行）。您需要通过在列元数据中设置“index_type: KEYS”来在 Cassandra 架构中启用此功能。
请参阅http://www.datastax.com/dev/博客/whats-new-cassandra-07-secondary-indexes 了解更多详细信息。
Cassandra 不提供否定，因此您的“NOT in items1[]”条件可能需要由客户端而不是 Cassandra 节点进行测试。您的 items1 和 items2 有多少个可能的值（只是少数，还是数千？）。
您可能需要纯粹为了回答这种特定类型的查询而设置一个列族，即具有某种基于 item1 和 item2 的复合键的查找表。然而，如果 item1 和 item2 有很多潜在值，那么维护服务器端可能会很困难，并且检索客户端的成本很高！
You may need to give a bit more detail to get a thorough answer to this one.
In Cassandra 0.7 onwards, you can use a secondary index to select rows according to column value (i.e. select rows where city=cityId). You will need to enable this in your Cassandra schema by setting "index_type: KEYS" in the column metadata.
See http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary-indexes for more details.
Cassandra does not provide negation, so your "NOT in items1[]" conditions may need to be tested by the client, not by the Cassandra nodes. How many possible values are there for your items1 and items2 (just a handful, or thousands?).
You will probably need to set up a column family purely for answering this specific type of query, i.e. a lookup table with some kind of compound key based on item1 and item2. However, this may be challenging to maintain server-side if there are many potential values of item1 and item2, and expensive to retrieve client-side!