sql常用语句

查询数据库表名

select table_name from information_schema.tables where table_schema='数据库名称'

1.添加PRIMARY KEY（主键索引）
mysql>ALTER TABLE `table_name` ADD PRIMARY KEY ( `column` )
2.添加UNIQUE(唯一索引)
mysql>ALTER TABLE `table_name` ADD UNIQUE (
`column`
)
3.添加INDEX(普通索引)
mysql>ALTER TABLE `table_name` ADD INDEX index_name ( `column` )
4.添加FULLTEXT(全文索引)
mysql>ALTER TABLE `table_name` ADD FULLTEXT ( `column`)
5.添加多列索引
mysql>ALTER TABLE `table_name` ADD INDEX index_name ( `column1`, `column2`, `column3` )

数据库备份：mysqldump -u root -p superzig-operatingtable > 存储路径
还原数据库：mysql -uroot -p 数据库名称 < sql语句

 

1.# 接触表和数据的管理 .frm 和idb
alter table tablename DISCARD tablespace;
2.关闭数据库 把idb复制到data中

3.开始数据库 关联frm和idb
alter table tablename IMPORT tablespace;

buffer pool

show variables  like "innodb_buffer_pool_size": 默认128M(字节展示)

show variables  like "innodb_buffer_pool_instances";默认是1  可以设置多个 如果每个实例分配的空间小于1GB 强制设置成1

show variables like "innodb_buffer_pool_chunk_size"; 默认是128M

数据页

show variables like "innodb_page_size"; 默认是16k

redolog

show variables like "innodb_log_buffer_size"; 默认是16k

show variables like "innodn_log_file_size";  默认是48M

show variables like "innodb_log_files_in_group"; 默认是2

show variables like "innodb_flush_log_at_trx_commit"; 默认是1 事务提交的时候直接刷盘

lru 和预读

show variables like "innodb_read_ahead_threshold"; 56线性预读

show variables like "innodb_random_read_ahead"; 默认关闭  13

show variables like "innodb_old_block_pct"; 37lru 老年区的比例 3/8

show variables like "innodb_old_block_time"; 1000  1s

刷脏页

show variables like "innodb_io_capacity" 默认200

show status      like "innodb_buffer_pool_pages_total" 8192

show status      like "innodb_buffer_pool_pages_dirty";

show variables like "innodb_max_dirty_pages_pct"; 75

show variables like "innodb_flush_neighbors"; on

show variables like "innodb_lru_scan_depth"; 1024

.idb存储

show variables like "innodb_file_per_table";

双写缓冲区

show variables like "innodb_doublewrite";

change buffer

show variables like "innodb_change_buffer_max_size"; 25