ScyllaDB 1.7 要支援 Cassandra 的 Counter 了

内容简介：ScyllaDB 1.7 要支援 Cassandra 的 Counter 了

Counter 是 Cassandra 裡一個特別的資料型態，總算是要 porting 進 ScyllaDB 了：「 Scylla 1.7 introduces experimental support for counters 」。

由於資料結構的特殊性，在文章裡有提到想像得到的限制：

• once deleted, counter column value cannot be used again—this is a consequence of the fact that counters can only be incremented or decremented, they cannot be set to any specific value
• a table cannot contain both counter and regular columns—without this limitation it wouldn’t be possible to provide proper atomicity and isolation guarantees for updates that modify both counters and regular columns in a single row
• counter columns cannot be members of primary key
• updates are not idempotent – in case of a write failure the client cannot safely retry the request
  counter columns cannot have time-to-live set

跟 Cassandra 一樣是透過 CRDT 實做的，行為上會是 eventually consistency：

Scylla implements counters using state-based conflict-free replicated data types (CRDT), which allow atomic operations, like increment or decrement, to be performed locally without the need for synchronization between nodes.

在「 Scylla Status and Roadmap 」這邊可以看到其他會在 1.7 出現的功能。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持 码农网

查看所有标签

本站部分资源来源于网络，本站转载出于传递更多信息之目的，版权归原作者或者来源机构所有，如转载稿涉及版权问题，请联系我们。