实施MySQL NDB Cluster的局限性是什么? [英] What are the limitations of implementing MySQL NDB Cluster?
问题描述
我想为MySQL Cluster 6实现NDB Cluster.我想对具有最少200万条记录的巨大数据结构进行此操作.
I want to implement NDB Cluster for MySQL Cluster 6. I want to do it for very huge data structure with minimum 2 million records.
我想知道实现NDB集群是否有任何限制.例如，RAM大小，数据库数量或NDB群集的数据库大小.
I want to know is if there are any limitations of implementing NDB cluster. For example, RAM size, number of databases, or size of database for NDB cluster.
推荐答案
200万个数据库?我假设你的意思是行".
2 million databases? I asssume you meant "rows".
无论如何，关于限制:要记住的最重要的事情之一是NDB/MySQL Cluster不是通用数据库.最值得注意的是，联接操作，以及子查询和范围操作(查询:从现在到一周前创建的订单)，可能比您预期的要慢得多.部分原因是由于数据分布在多个节点上.尽管已进行了一些改进，但Join性能仍然令人非常失望.
Anyway, concerning limitations: one of the most important things to keep in mind is that NDB/MySQL Cluster is not a general purpose database. Most notably, join operations, but also subqueries and range opertions (queries like: orders created between now and a week ago), can be considerably slower than what you might expect. This is in part due to the fact that the data is distributed across multiple nodes. Although some improvements have been made, Join performance can still be very disappointing.
另一方面，如果您需要处理许多(最好是较小的)并发事务(通常是通过主键进行单行更新/插入/删除查找)，并且可以将所有数据保留在内存中，则可以是一个非常可扩展的高性能解决方案.
On the other hand, if you need to deal with many (preferably small) concurrent transactions (typically single row updates/inserts/delete lookups by primary key) and you mangage to keep all of your data in memory, then it can be a very scalable and performant solution.
您应该问自己为什么要集群.如果您只是希望拥有自己现有的普通数据库(除了增加了99,999％的可用性)，那么您可能会感到失望.当然，MySQL群集可以为您提供出色的可用性和正常运行时间，但是您的应用程序的工作负载可能不太适合Things群集.另外，您也许可以使用另一种高可用性解决方案来增加传统数据库的正常运行时间.
You should ask yourself why you want cluster. If you simply want your ordinary database that you have now, except with added 99,999% availability, then you may be disappointed. Certainly MySQL cluster can provide you with great availability and uptime, but the workload of your app may not be very well suited for the thtings cluster is good for. Plus you may be able to use another high availability solution to increase the uptime of your otherwise traditional database.
BTW - here's a list of limitations as per the doc: http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-limitations.html
但是无论您做什么，都请尝试集群，看看它是否对您有好处. MySQL群集不是"MySQL + 5个9".您会在尝试时找到答案.
But whatever you do, try out cluster, see if its good for you. MySQL cluster is not "MySQL + 5 nines". You'll find out when you try.
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