Issues related to MySQL middleware atlas

Altas Introduction:
Atlas is a MySQL protocol-based data mid-tier project developed and maintained by Qihoo, a web platform infrastructure team.
It is based on MySQL's official launch of the Mysql-proxy 0.8.2 version, modified a large number of bugs, adding a lot of features


key features implemented by Altas:
1. Read/write separation (verified)
2. Load Balancing from the library (verified)
3.sharding Support (to be verified)
4. Automatic sub-table (to be verified)



Automatic sub-table function in Atlas (non-sharding)
(1). Unable to collapse library table function
(2). Automatic table-building feature not supported
(3). Table Rule Comparison single (only by the primary key to the mode of the table)
(4). One operation can only hit one table (but it can be manipulated by a specific child table name) and cannot be manipulated across child tables. You must first obtain a specific child table name before the operation.
(5). At this stage, Atlas supports only simple queries and DML operations (SELECT,UPDATE,INSERT,DELETE,REPLACE), truncate is not supported, and DDL does not support
(6) Insert must be in advance to obtain the ID (Specify the ID, let Atlas know which table to manipulate), otherwise you can only insert the first child table (not let it self-growth)
Https://github.com/Qihoo360/Atlas/wiki/Atlas%E7%9A%84%E5%88%86%E8%A1%A8%E5%8A%9F%E8%83%BD%E7%AE%80%E4%BB%8B


sharding function of Atlas ()
There are two ways of sharding (range, hash)
(1). Only one dbgroup can be hit per write (that is, distributed transactions are not supported)
(2). Support for subqueries is not good, and it is possible to return incorrect results (pending validation)
(3). Only simple select queries are supported (if the crash query, Limit,order by, group BY, join, ON, Count, Max, MIN, etc. are not supported),
(4). A simple crash query can be performed, for example: SELECT * from TT where tname= ' DDD '
(5). sharding tables cannot be combined with non-sharding tables
(5) extension problem (The Shard supports static extension (requires restart of Atlas service), hash does not support extension).

Https://github.com/Qihoo360/Atlas/wiki/Atlas-Sharding



the pros and cons of range and hash for sharding
(1) range is suitable for range lookup scenarios and does not improve concurrency performance.
(2) hash improves concurrent insert performance and is not suitable for range lookups.
(3) Hash,range supports static scaling (requires server restart),



Performance Issues: Performance is still relatively good
when concurrency is small, the performance of Atlas cannot be fully played
when concurrency is large, select performance degrades to direct-attached 60%,DML operations by 80%, but you can configure multiple Atlas in the previous section to compensate for this .
In addition, the number of working threads in Atlas (Event-threads) has a large impact on performance, and the official test gives the data that the event-threads is set to twice times the number of CPU cores, with the best performance.
Finally, the choice of the Atlas server is best to choose a better CPU machine, memory and disk dependence is small

Atlas Performance Testing
Https://github.com/Qihoo360/Atlas/wiki/Atlas%E7%9A%84%E6%80%A7%E8%83%BD%E6%B5%8B%E8%AF%95




installation of Altas
Http://www.mamicode.com/info-detail-556437.html
Https://github.com/Qihoo360/Atlas/wiki/Atlas%E7%9A%84%E5%AE%89%E8%A3%85

official documents of Altas
Https://github.com/Qihoo360/Atlas/wiki

related issues of Altas
Http://www.2cto.com/database/201503/382397.html

This article is from the "SQL Server MySQL" blog, so be sure to keep this source http://dwchaoyue.blog.51cto.com/2826417/1748683

Issues related to MySQL middleware atlas