转载--使用tuning-primer.sh检测一些参数注释

使用tuning-primer.sh 可以自动检测mysql的性能和一些建议，转载一篇文章列举一些参数意义
脚本支持my.cnf文件，可以把user, password, host, socket等连接参数放在~/.my.cnf文件里，如果使用了自定义的socket文件，请修改tuning-primer.sh文件中关于socket文件位置的变量。

运行 tuning-primer.sh显示说明

SLOW QUERIES	慢查询检查
SLOW QUERIESThe slow query log is enabled.	说明我已经启用了慢查询记录功能。也就是参数 slow_query_log = 1
Current long_query_time = 5.000000 sec.	慢查询的阀值时间。也就是参数 long_query_time = 5
You have 17 out of 638844 that take longer than 5.000000 sec. to complete	说明慢查询日志中记录了17条查询时间超过5秒的语句。 slow_query_log_file=/data/ats_db/mysql-slow.log设置慢查询日志路径。使用 mysqldumpslow命令查询慢日志
Your long_query_time seems to be fine	慢查询阀值时间设置得在推荐的范围内
BINARY UPDATE LOG	更新二进制日志文件
The binary update log is enabled	这项说明启用了bin-log日志功能。参数 log-bin = /data/ats_db/mysql-bin
Binlog sync is not enabled, you could loose binlog records during a server crash	没有启用 sync_binlog 选项。也即是将二进制日志实时写入到磁盘通过 sync_binlog=1来指定
WORKER THREADS	工作线程
Current thread_cache_size = 8	当前线程缓存大小。 thread_concurrency = 8
Current threads_cached = 7	Show status like ‘threads_cached’
Current threads_per_sec = 0	脚本先执行Show status like ‘Threads_cached’查看当前的线程创建情况，然后sleep 1后在执行相同的命令，最终后者减去前者的数就是每秒线程创建数。
Historic threads_per_sec = 0	该值是使用Threads_cached /uptime获得的。
Your thread_cache_size is fine
MAX CONNECTIONS	最大连接数
Current max_connections = 1024	当前配置文件中设置的并发连接数
Current threads_connected = 2	当前线程连接诶数。 show status like ‘Threads_connected’
Historic max_used_connections = 4	show status like ‘Max_used_connections’;
The number of used connections is 0% of the configured maximum.	这个值使用 Max_used_connections*100/ max_connections得出。
You are using less than 10% of your configured max_connections. Lowering max_connections could help to avoid an over-allocation of memory See “MEMORY USAGE” section to make sure you are not over-allocating	Max_used_connections的值不足max_connections值的10%。设置合适的max_connections值有助于节省内存。
MEMORY USAGE	内存使用
Max Memory Ever Allocated : 841 M	Max Memory Ever Allocated = max_memory
Configured Max Per-thread Buffers : 28.40 G	Configured Max Per-thread Buffers = per_thread_buffers
Configured Max Global Buffers : 586 M	Configured Max Global Buffers = per_thread_max_buffers
Configured Max Memory Limit : 28.97 G	Configured Max Memory Limit = total_memory 这 一项很重要，他是将各个缓存的大小累加，然后同max_connections相乘，从而得出当达到max_connections后需要分配的内存有多 少。我这里由于max_connections写得很大，造成了最大内存限制超过了真实内存很多，所以建议不要随意增大max_connections的 值。减小 max_connections的值，最终保证最大内存限制在真实内存的90%以下。
Physical Memory : 7.79 G	实际物理内存
Max memory limit exceeds 90% of physical memory
per_thread_buffers (read_buffer_size+read_rnd_buffer_size +sort_buffer_size+thread_stack+ join_buffer_size+binlog_cache_size)*max_connectionsper_thread_max_buffers (read_buffer_size+read_rnd_buffer_size +sort_buffer_size+thread_stack +join_buffer_size+binlog_cache_size)*max_used_connections global_buffers innodb_buffer_pool_size+innodb_additional_mem_pool_size+innodb_log_buffer_size+ key_buffer_size+query_cache_size max_memory=global_buffers+per_thread_max_buffers total_memory=global_buffers+per_thread_buffers
KEY BUFFER	Key 缓冲
Current MyISAM index space = 222 K	当前数据库MyISAM表中索引占用磁盘空间
Current key_buffer_size = 512 M	MySQL配置文件中key_buffer_size 设置的大小
Key cache miss rate is 1 : 3316	Key_read_requests/ Key_reads 这里说明3316次读取请求中有1次丢失(也就是说1次读取磁盘)
Key buffer free ratio = 81 %	key_blocks_unused * key_cache_block_size / key_buffer_size * 100
Your key_buffer_size seems to be fine
QUERY CACHE	Query 缓存
Query cache is enabled	该项说明 我们指定了query_cache_size 的值。如果query_cache_size=0的话这里给出的提示是： Query cache is supported but not enabled Perhaps you should set the query_cache_size
Current query_cache_size = 64 M	当前系统query_cache_size 值大小 [F]
Current query_cache_used = 1 M	query_cache_used =query_cache_size-qcache_free_memory
Current query_cache_limit = 128 M	变量 query_cache_limit 大小
Current Query cache Memory fill ratio = 1.79 %	query_cache_used/query_cache_size *100%
Current query_cache_min_res_unit = 4 K	show variables like ‘query_cache_min_res_unit’;
Your query_cache_size seems to be too high. Perhaps you can use these resources elsewhere	这项给出的结论是query_cache_size的值设置的有些过高。其比对标准是 “Query cache Memory fill ratio”的值如果小于<25%就会给出这个提示。可以将这些资源应用到其他的地方
MySQL won’t cache query results that are larger than query_cache_limit in size	MySQL不会将大于query_cache_limit的查询结果进行缓存
show status like ‘Qcache%’;Qcache_free_blocks        10 Qcache_free_memory        65891984 Qcache_hits            14437 Qcache_inserts            707 Qcache_lowmem_prunes    0 Qcache_not_cached        216 Qcache_queries_in_cache    540 Qcache_total_blocks        1191
SORT OPERATIONS	SORT 选项
Current sort_buffer_size = 6 M	show variables like ’sort_buffer%’;
Current read_rnd_buffer_size = 16 M	show variables like ‘read_rnd_buffer_size%’;
Sort buffer seems to be fine
JOINS	JOINS
Current join_buffer_size = 132.00 K	show variables like ‘join_buffer_size%’;join_buffer_size= join_buffer_size+4kb
You have had 6 queries where a join could not use an index properly	这里的6是通过 show status like ‘Select_full_join’; 获得的
You should enable “log-queries-not-using-indexes” Then look for non indexed joins in the slow query log. If you are unable to optimize your queries you may want to increase your join_buffer_size to accommodate larger joins in one pass.Note! This script will still suggest raising the join_buffer_size when ANY joins not using indexes are found.	你需要启用 “log-queries-not-using-indexes” 然后在慢查询日志中看是否有取消索引的joins语句。如果不优化查询语句的话，则需要增大join_buffer_size。
OPEN FILES LIMIT	文件打开数限制
Current open_files_limit = 1234 files	show variables like ‘open_files_limit%’;
The open_files_limit should typically be set to at least 2x-3xthat of table_cache if you have heavy MyISAM usage.	如果系统中有很多的MyISAM类型的表，则建议将open_files_limit 设置为2X~3X的table_open_cache show status like ‘Open_files’;open_files_ratio= open_files*100/open_files_limit 如果open_files_ratio 超过75% 则需要加大open_files_limit
Your open_files_limit value seems to be fine
TABLE CACHE	TABLE 缓存
Current table_open_cache = 512 tables	show variables like ‘table_open_cache’;
Current table_definition_cache = 256 tables	show variables like ‘ table_definition_cache ‘;
You have a total of 368 tables	SELECTCOUNT(*) FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_TYPE=’BASE TABLE’
You have 371 open tables.	show status like ‘Open_tables’;
The table_cache value seems to be fine	Open_tables /table_open_cache*100% < 95%
You should probably increase your table_definition_cache value.	table_cache_hit_rate =open_tables*100/opened_tables
TEMP TABLES	临时表
Current max_heap_table_size = 16 M	show variables like ‘max_heap_table_size’;
Current tmp_table_size = 16 M	show variables like ‘tmp_table_size’;
Of 285 temp tables, 11% were created on disk	Created_tmp_tables=285created_tmp_disk_tables*100/ (created_tmp_tables+created_tmp_disk_tables)=11%
Created disk tmp tables ratio seems fine
TABLE SCANS	扫描表
Current read_buffer_size = 6 M	show variables like ‘read_buffer_size’;
Current table scan ratio = 9 : 1	read_rnd_next =show global status like ‘Handler_read_rnd_next’; com_select= show global status like ‘Com_select’; full_table_scans=read_rnd_next/com_select Current table scan ratio = full_table_scans : 1″ 如果表扫描率超过4000，说明进行了太多表扫描，很有可能索引没有建好，增加read_buffer_size值会有一些好处，但最好不要超过8MB。
read_buffer_size seems to be fine
TABLE LOCKING	TABLE LOCKING
Current Lock Wait ratio = 0 : 5617	show global status like’Table_locks_waited’; show global status like ‘Questions’; 如果 Table_locks_waited=0 Current Lock Wait ratio = 0: Questions
Your table locking seems to be fine