卡桑德拉集合地图索引

Question

我有一个 Cassandra table，它的一列看起来像这样

 "ArticlesViewed" frozen<map<int, frozen<list<int>>>>

   and it contains data like 

       ArticlesViewed
       -----------------------------------------------
       {400: [9, 19, 11, 12], 545: [183, 44, 25, 16, 97]}
       {812: [2, 44, 41, 22], 376: [123, 14, 15, 16, 47]}
       {134: [9, 10, 11, 92], 111: [533, 14, 15, 16, 27]}

我想在此列上创建索引（不允许过滤）但它不允许我这样做

 cqlsh>CREATE INDEX ON user_profile("ArticlesViewed");

 [Invalid query] message="Cannot create values() index on frozen column ArticlesViewed.
 Frozen collections only support full() indexes"

  Also,i want to query on the <value>  {400: [9, 19, 11, 12],of the column like

 select "ArticlesViewed" from  user_profile where "ArticlesViewed" =19;

请建议我一些方法来做到这一点..任何帮助将不胜感激

Answer 1

您不能在冻结的集合元素上创建索引

您必须在冻结集合上创建完整索引

Create an index on a full FROZEN collection. An FULL index can be created on a set, list, or map column of a table that doesn't have an existing index.

To index collection entries, you use the FULL keyword and collection name in nested parentheses

例如：

CREATE INDEX on user_profile(full(articlesviewed));

使用全索引，如果要查询articlesviewed必须指定全集合值。因为它被冻结了。

如果你有数据:

 userid | articlesviewed
--------+----------------------------------
      1 | {1: [1, 2, 3], 10: [10, 20, 30]}

您的查询应包含 articlesviewed 的完整值

SELECT * FROM user_profile WHERE articlesviewed = {1: [1, 2, 3], 10: [10, 20, 30]};

卡桑德拉集合地图索引

cassandra collection map indexing

indexing

bigdata

cassandra

cqlsh