Second, the MySQL architecture introduction

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The plug-in storage engine architecture separates query processing from the storage extraction of other system tasks already data

First layer: Connection layer:

The top level is a number of client and connection services, including local sock traffic and most TCP/IP-like communications based on client/server-side tools. It mainly accomplishes some security schemes like connection processing, authorization authentication, and related. The concept of a thread pool is introduced on this layer to provide threads for clients that authenticate secure access. SSL-based secure links can also be implemented on this layer. The server also verifies the operational permissions that it has for each client that is securely connected.

Second layer: Business logic processing layer

The main completion of most core service functions, such as SQL excuses, and complete caching of queries, SQL analysis and optimization, and the execution of some built-in functions. The functionality of all cross-storage engines is also implemented at this level, such as procedures, functions, and so on. At this level, the server parses the query and creates the corresponding internal parse tree, and completes the corresponding optimizations such as determining the order of the query tables, whether the indexes are used, and finally generating the corresponding actions. In the case of a SELECT statement, the server also queries the internal cache. The performance of the system can be improved well if the cache space is large enough for read operations.

Layer Three: Pluggable storage engine layer

Storage engine layer, the storage engine is really responsible for the data in MySQL storage and extraction, the server through the API to communicate with the storage engine. Different storage engines have different functions, so that we can choose according to our actual needs. MyISAM and InnoDB are described later

Layer Fourth: File storage tier

Data storage tier, primarily storing data on file systems running on bare devices and completing interactions with the storage engine

Storage Engine Introduction ---With command view: show engines;

Show variables likes '%storeage_engine% '

MyISAM and InnoDB differences

Second, the MySQL architecture introduction