如何通过在Cassandra中设置单独的生存时间(TTL)属性来使集合的每个元素到期? [英] How to expire each element of a collection by setting an individual time-to-live (TTL) property in Cassandra?

问题描述

如何通过在Cassandra中设置单独的生存时间(TTL)属性来使集合的每个元素到期?

How to expire each element of a collection by setting an individual time-to-live (TTL) property in Cassandra?

文档在这里，但我找不到示例.( https://docs.datastax.com/en/cql/3.3/cql/cql_using/useExpire.html )

the documentation is here, but I cannot find an example. (https://docs.datastax.com/en/cql/3.3/cql/cql_using/useExpire.html)

推荐答案

如果要在cassandra的同一列集合(集合，列表，地图)中使用不同的TTL.

在此示例中喜欢:

有一个表-> tableName
文本类型的一列(col1)主键
类型为set< long>

If you want to have different TTL in a same column collection (set, list, map) of cassandra.

Do like in this example:

There is a table -> tableName
whih one column (col1) primary key of text type
A column(col2) of type set <long>

UPDATE tableName USING TTL 30 SET col2=col2+{11} WHERE col1=-10;
UPDATE tableName USING TTL 88 SET col2=col2+{22} WHERE col1=-10;

在该示例中，我将设置值设置为TTL = 30的{11}和TTL = 88的{22}.当一个元素超过TTL时，它将被自动删除.
当集合中的所有元素都超过TTL并且集合为空时，该行也会被删除.

In the example I am upserting to values to the set, {11} with TTL=30 and {22} with TTL=88.
When one element exeeds the TTL it is automaticaly deleted.
When all the elements in the set exceeds the TTL and the set is empty, the row is also deleted.

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