为什么nosql与cassandra而不是mysql？ [英] Why nosql with cassandra instead of mysql?

问题描述

我在大数据库（几百GB）工作，Mysql现在给我或多或少的满意。

I work on large database (hundreds of GB) and Mysql now gives me more or less satisfaction. I hesitate to cassandra on launch.

我想知道一切之前，所以这种DBMS NoSQL应该比MySQL快？

What I want to know everything before, so this kind of DBMS NoSQL is supposed to be faster than MySQL?

几点：

• 行的列数的变化
  在Mysql中，必须事先定义它们。列
  在表的结构中设置。
  NoSQL，它们可以变化。
  在固定结构上存在真正的差异性能？为什么？

• The change in the number of column on a row In Mysql, they must all be defined in advance. The columns set in the structure of the table. NoSQL in, they can be varied. There is real difference performance on a fixed structure ? and why ?

不要使关系有利于性能。
好​​的，但我没有义务做一个关系表
Mysql。我使用聚合表，即
只包含从其他表派生的数据的表，I
以防止过于昂贵的关节。
再次，如果我在Mysql中使用这个模型
，什么级别的性能差异？
举个例子，作者的 http ：//www.rackspacecloud.com/blog/2010/05/12/cassandra-by-example/
在消息USERLINE中插入X个跟随者的次数。
我可以在MySQL中做。

Do not make the relationship is beneficial for performance. Ok but I am not obliged to make a relational table Mysql. I use aggregated tables, ie tables that contain only data derived from other tables, I to prevent the joints which are too expensive. Again what level performance differences if I use this model in Mysql? To take one example, the author of http://www.rackspacecloud.com/blog/2010/05/12/cassandra-by-example/ insert X number of times the follower in the message USERLINE pusher. I could do that in MySQL.

可扩展性，可扩展性，可扩展性...我喜欢它，cassandra允许我存储我的数据不同的服务器（不含SAN）？
我不是在这里复制，我说的是一个单一的NoSQL服务器跨多个物理服务器。

Scalability, scalability, scalability ... I like it, do cassandra allow me to store my data on different servers (without SAN) ? I am not talking here of replication, I speak of a single NoSQL server across multiple physical server.

在计算。 MySQL提供像我一样的功能像SUM，AVG ...非常有用，以避免我重新聚合我的数据在其他表。我还没有看到等价的
cassandra？

Live at the calculations. MySQL provides functions like me as SUM, AVG ... that are very useful to avoid me to re-aggregating my data in other tables. I have not seen equivalent cassandra ?

在Mysql我索引几个字段在一个。例如，我的表在多个列上有一个主键，我选择是在functionaly。 cassandra怎么写呢？为每行的单个标识符连接？我想我还没有完全掌握索引的管理。是否针对集成或上游重新计算？

What about the indexes. On Mysql I index several fields in one. For example my tables have a primary key on multiple columns and I select are in functionaly. cassandra on how to write it? The concatenated for a single identifier for each row? I think I have not completely grasped the management of indexes. Are recalculated for the integration or upstream?

异步请求。一个假的说法，对我来说，Mysql可以使用INSERT / UPDATE LOW_PRIORITY。

The asynchronous requests. A false argument that it seems to me, Mysql can be done with INSERT / UPDATE LOW_PRIORITY.

周围。谢谢你启发我。

推荐答案

我真的不明白为什么人们比较Cassandra和MySQL的数据提供者

I really don't understand why people compare data providers like Cassandra and MySQL together -- you're really comparing apples and oranges here.

是的，NoSQL解决方案在某些情况下可以提供比SQL更好的性能。但不要忘记 他们提供的速度 - 他们放弃了你经常认为在SQL中的几个检查。例如，您不会在NoSQL系统中看到事务，例如事务，也不会有作为SQL系统一部分的连接和数据聚合特性。您对数据一致性的保证很少。

Yes, NoSQL solutions can give better performance than SQL in some cases. But don't forget the reason they provide that speed -- they give up on several of the checks that you often take for granted in SQL. For example, you will not see things like transactions in a NoSQL system, nor are you going to have the kinds of joins and data aggregation features that you get as part of a SQL system. You get very few guarantees with respect to consistency of the data.

对于99％的应用程序，它不值得花时间和精力。如果你是facebook或twitter，在那里你有大量的非结构化数据，你不在乎你是否实际丢失了一些东西的shuffle的数据，或有延迟，当数据可用时插入后，NoSQL是好的。然而，对于绝大多数应用程序，你仍然应该坚持使用SQL。

For 99% of applications it's simply not worth the time and effort. If you are facebook or twitter, where you have enormous quantities of unstructured data, where you don't care if you actually lose some data in the shuffle of things, or have delays with respect to when data is available after it is inserted, NoSQL is just fine. However, for the vast majority of applications, you should still be sticking with SQL.

对于可扩展性，如果一个庞大的网站，如Stack Overflow或Ebay可以运行在SQL，我不明白为什么你的应用程序不能在SQL上运行。

As for scalability, if an enormous site like Stack Overflow or Ebay can run on top of SQL, I don't see why your application cannot run on top of SQL.

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