Shulou(Shulou.com)06/03 Report--

In February 2005, Qunar was established in Beijing, and the database of Qunar was also completed. Huang Yong, a database architect from Qunar, joked at the SACC conference that the database at that time was a small workshop model, a MySQL architecture in a stand-alone room. After that, Qunar database architecture has gone through four stages, gradually transitioning to today's cross-room QMHA architecture, which can be deployed in different places to ensure high availability and security. Along the way, what has promoted the database architecture change of Qunar? What problems have you encountered? How to solve the problem?

The budding and developing stage of Qunar-MySQL in single computer room to MMM in single computer room

In the past, when business development and technology were relatively underdeveloped, MMM architecture was a very popular deployment method, which was widely used within major companies at that time. Huang Yong said that with the development of business, this simple MMM architecture has gradually exposed many problems, such as the complexity of operation and maintenance, the need to bind VIP, the deployment and modification of configuration files, and the lack of peripheral monitoring tools. Secondly, there are also great problems in network partition, such as Master "fake death" leads to misswitching, database double writing leads to data confusion, VIP does not drift or drift failure and so on.

In 2012, the new features of MySQL version 5.6 and above were not supported, which also marked the end of the MMM era.

The rapid development of Qunar-PXC architecture in the same computer room

With the rapid growth of business, it promotes another innovation of the architecture. Qunar began to apply the PXC architecture and joined the Sentinel cluster. At this time, the architecture can automatically failover, manual switchover, read-write separation, load balancing, namespace service, global uniqueness, transparency, expansion, migration and upgrade. The PXC single node can read up to 5W qps and write up to 15K qps.

The reason why Qunar will later abandon PXC and choose QMHA is because PXC itself has some limitations. For example, the machine bucket short board effect between nodes, the client is easy to avalanche; large transactions and dense transactions lead to high pressure on PXC nodes, fc generation; DDL operation will kill other transactions, but DDL can not be cancelled; mutual check leads to write performance degradation, switching does not affect front-end write, but try not to write too long; high network latency between computer rooms affects client QPS, and the more machine nodes, the greater the QPS impact New structures such as PXC and MGR lead to the high cost of DBA learning, which requires long-term learning and experience to master.

Qunar stationary period-QMHA architecture across computer rooms

Since 2015, Qunar has adopted the cross-room QMHA architecture. GTID is easy to maintain and switch, data differences between master and slave nodes can be known, distributed sentinel reduces misswitching and network partition raft algorithm, improves data node consistency while improving cluster security and availability, multi-thread replication and can cross computer rooms and network segments. The global namespace notifies the client to update the configuration.

Huang Yong said that in the future, the cross-room QMHA architecture will gradually solve the problems of automatic completion of binlog, delay processing and weight control. MHA can automatically complete binlog,PXC or IST QMHA needs to be able to automatically complete binlog to the original master node after failover. Both PXC and QMHA need to ensure that read-only data sources can be controlled according to weight ratio, which is helpful for special processing of special machines.

After four stages of development, the database architecture of Qunar is becoming more and more stable, which is enough to meet the needs of daily business. The DBA operating platform developed by Qunar Network-Butian combines the experience and wisdom of the whole team of Qunar database. If you are interested, you might as well try it!

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