MySQL Chapter 3Linux教学课件.ppt

RHEL Clustering Storage Management 解析：解析树 Differential 事务日志 重做日志 redo log 撤消日志 undo log 日志组 MySQL Storage Engine Transaction User Management Backup and Recovery Caching and MySQL MySQL Arch MySQL’s Logical Architecture MySQL’s Logical Architecture The topmost layer contains the services that aren’t unique to MySQL Services most network-based client/server tools or servers need: connection handling, authentication, security, and so forth The second layer Much of MySQL’s brains are here, including the code for query parsing, analysis, optimization, caching, and all the built-in functions (e.g., dates, times, math, and encryption) Any functionality provided across storage engines lives at this level: stored procedures, triggers, and views, for example The third layer contains the storage engines They are responsible for storing and retrieving all data stored “in” MySQL The server communicates with them through the storage engine API Connection Management and Security Each client connection gets its own thread within the server process The connection’s queries execute within that single thread, which in turn resides on one core or CPU The server caches threads, so they don’t need to be created and destroyed for each new connection When clients (applications) connect to the MySQL server, the server needs to authenticate them Authentication is based on username, originating host, and password X.509 certificates can also be used across an Secure Sockets Layer (SSL) connection Once a client has connected, the server verifies whether the client has privileges for each query it issues Optimization and Execution MySQL parses queries to create an internal structure (the parse tree), and then applies a variety of optimizations, such as rewriting the query determining the order in which it will read tables choosing which indexes to use You can pass hints to the optimizer through special keywords in the query, affecting its decision-making process You can also ask the server to