MySQL Study之--MySQL体系结构深入解析
MySQL Study之--MySQL体系结构深入解析
MySQL体系架构
由连接池组件、管理服务和⼯工具组件、sql接口组件、查询分析器组件、优化器组件、缓冲组件、插件式存储引擎、物理⽂文件组成。mysql是独有的插件式体系结构,各个存储引擎有自己的特点。
MySQL内存结构：
Mysql 进程结构
Mysql不像oracle那样是通过多进程来完毕其功能的。默认情况下，InnoDB存储引擎的后台线程有7个：
4个IO thread，
1个master thread，
1个锁（lock）监控线程。
1个错误监控线程。
在InnoDB Plugin版本号開始添加了默认IO thread的数量，默认的read thread和write thread分别增大到了4个。而且不再使用innodb_file_ io_threads參数，而是分别使用innodb_read_io_threads和innodb_write_io_threads參数。
查看mysql thread：
<strong><span style="font-size:14px;">mysql> show variables like 'innodb_%version%';</span></strong> +----------------+-------+ | Variable_name | Value | +----------------+-------+ | innodb_version | 1.2.4 | +----------------+-------+ 1 row in set (0.00 sec)
<strong><span style="font-size:14px;">mysql> show engine innodb status;</span></strong> ===================================== 150709 15:26:40 INNODB MONITOR OUTPUT ===================================== Per second averages calculated from thelast 12 seconds ----------------- BACKGROUND THREAD ----------------- srv_master_thread loops: 0 srv_active, 0srv_shutdown, 804 srv_idle srv_master_thread log flush and writes: 804 ---------- SEMAPHORES ---------- OS WAIT ARRAY INFO: reservation count 2 OS WAIT ARRAY INFO: signal count 2 Mutex spin waits 0, rounds 0, OS waits 0 RW-shared spins 2, rounds 60, OS waits 2 RW-excl spins 0, rounds 0, OS waits 0 Spin rounds per wait: 0.00 mutex, 30.00RW-shared, 0.00 RW-excl ------------ TRANSACTIONS ------------ Trx id counter 5377 Purge done for trx's n:o < 4872 undo n:o< 0 History list length 1 LIST OF TRANSACTIONS FOR EACH SESSION: ---TRANSACTION 0, not started MySQL thread id 3, OS thread handle0x7f1656c75700, query id 5 localhost root init show engine innodb status -------- FILE I/O -------- <strong>I/O thread 0 state: waiting for completedaio requests (insert buffer thread) I/O thread 1 state: waiting for completedaio requests (log thread) I/O thread 2 state: waiting for completedaio requests (read thread) I/O thread 3 state: waiting for completedaio requests (read thread) I/O thread 4 state: waiting for completedaio requests (read thread) I/O thread 5 state: waiting for completedaio requests (read thread) I/O thread 6 state: waiting for completedaio requests (write thread) I/O thread 7 state: waiting for completedaio requests (write thread) I/O thread 8 state: waiting for completedaio requests (write thread) I/O thread 9 state: waiting for completedaio requests (write thread) Pending normal aio reads: 0 [0, 0, 0, 0] ,aio writes: 0 [0, 0, 0, 0] ,</strong> ibufaio reads: 0, log i/o's: 0, sync i/o's: 0 Pending flushes (fsync) log: 0; bufferpool: 0 283 OS file reads, 5 OS file writes, 5 OSfsyncs 0.00 reads/s, 0 avg bytes/read, 0.00writes/s, 0.00 fsyncs/s ------------------------------------- INSERT BUFFER AND ADAPTIVE HASH INDEX ------------------------------------- Ibuf: size 1, free list len 0, seg size 2,0 merges merged operations: insert 0, delete mark 0, delete 0 discarded operations: insert 0, delete mark 0, delete 0 Hash table size 276707, node heap has 0buffer(s) 0.00 hash searches/s, 0.00 non-hashsearches/s --- LOG --- Log sequence number 1611537 Log flushed up to 1611537 Pages flushed up to 1611537 Last checkpoint at 1611537 0 pending log writes, 0 pending chkp writes 8 log i/o's done, 0.00 log i/o's/second ---------------------- BUFFER POOL AND MEMORY ---------------------- Total memory allocated 137363456; inadditional pool allocated 0 Dictionary memory allocated 39010 Buffer pool si
