mysql 查询结构信息及锁信息脚本
--查看创建的索引的CARDINALITY比率
--通常cardinality达到表数据的10%左右建索引会有意义
--如果是一个组合索引，索引第一位的cardinality表示第一个列的cardinality大小，第二列表示第一列和第二列共同的cardinality值
SELECT
T1.TABLE_SCHEMA,
T1.TABLE_NAME,
T2.INDEX_NAME,
ROUND(T2.CARDINALITY / T1.TABLE_ROWS * 100, 2) AS RATE
FROM
INFORMATION_SCHEMA.TABLES T1,
INFORMATION_SCHEMA.STATISTICS T2
WHERE
T1.TABLE_SCHEMA = T2.TABLE_SCHEMA
AND T1.TABLE_NAME = T2.TABLE_NAME
AND T2.SEQ_IN_INDEX = (SELECT
MIN(T3.SEQ_IN_INDEX)
FROM
INFORMATION_SCHEMA.STATISTICS T3
WHERE
T2.TABLE_NAME = T3.TABLE_NAME
AND T2.TABLE_SCHEMA = T3.TABLE_SCHEMA
AND T2.INDEX_NAME = T3.INDEX_NAME)
AND T1.TABLE_SCHEMA NOT IN ('MYSQL','PERFORMANCE_SCHEMA','INFORMATION_SCHEMA','SYS')
AND T1.TABLE_ROWS >=100
ORDER BY RATE;
--查看锁阻塞
-- 查看锁的SQL
SELECT
t3.trx_id waiting_trx_id,
t3.trx_mysql_thread_id waiting_thread,
t3.trx_query waiting_query,
t2.trx_id blocking_trx_id,
t2.trx_mysql_thread_id blocking_thread,
t2.trx_query blocking_query
FROM
information_schema.innodb_lock_waits t1,
information_schema.innodb_trx t2,
information_schema.innodb_trx t3
WHERE
t1.blocking_trx_id = t2.trx_id
AND t1.requesting_trx_id = t3.trx_id;
--查询出哪些表不是InnoDB引擎的
SELECT
TABLE_SCHEMA,
TABLE_NAME,
TABLE_TYPE,
ENGINE,
CREATE_TIME,
UPDATE_TIME,
TABLE_COLLATION
FROM
INFORMATION_SCHEMA.TABLES
WHERE
TABLE_SCHEMA NOT IN ('information_schema' , 'mysql', 'performance_schema', 'sys')
AND ENGINE <> 'InnoDB';
--生成修改存储引擎的语句
SELECT
-- TABLE_SCHEMA,
-- TABLE_NAME,
-- TABLE_TYPE,
-- ENGINE,
-- CREATE_TIME,
-- UPDATE_TIME,
-- TABLE_COLLATION,
CONCAT('alter table ', TABLE_SCHEMA,'.',TABLE_NAME, ' engine=InnoDB;') AS alter_sql
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_SCHEMA NOT IN
('information_schema', 'mysql', 'performance_schema', 'sys')
AND ENGINE <> 'InnoDB';
-- 查看指定数据库的表信息
SET @table_schema='employees';
SELECT
table_name,
table_type,
engine,
table_rows,
avg_row_length,
data_length,
index_length,
table_collation,
create_time
FROM
information_schema.tables
WHERE
table_schema = @table_schema
ORDER BY table_name;
-- 查看会话连接信息
SELECT
THREAD_ID,
name,
type,
PROCESSLIST_ID,
PROCESSLIST_USER AS user,
PROCESSLIST_HOST AS host,
PROCESSLIST_DB AS db,
PROCESSLIST_COMMAND AS cmd,
PROCESSLIST_TIME AS time,
PROCESSLIST_STATE AS state,
PROCESSLIST_INFO AS info,
CONNECTION_TYPE AS type,
THREAD_OS_ID AS os_id
FROM
performance_schema.threads
WHERE
type = 'FOREGROUND'
ORDER BY THREAD_ID;
-- CHARACTER_SETS 查看数据库支持的字符集
SELECT * FROM INFORMATION_SCHEMA.CHARACTER_SETS
WHERE CHARACTER_SET_NAME LIKE 'utf%';
SHOW CHARACTER SET LIKE 'utf%';
-- COLLATIONS 字符序
-- 用于指定数据集如何排序，以及字符串的比对规则
SELECT * FROM INFORMATION_SCHEMA.COLLATIONS
WHERE COLLATION_NAME LIKE 'utf%';
SHOW COLLATION LIKE 'utf%';
-- 查看表结构定义信息
SELECT
table_name,
COLUMN_NAME,
ordinal_position,
DATA_TYPE,
IS_NULLABLE,
COLUMN_DEFAULT,
column_type,
column_key,
character_set_name,
collation_name
FROM
INFORMATION_SCHEMA.COLUMNS
WHERE
table_name = 'employees'
AND table_schema = 'employees';
show columns from employees from employees;
desc employeees.employees;
-- 查看支持的引擎
SELECT * FROM INFORMATION_SCHEMA.ENGINES;
show ENGINES;
-- 查看数据库的数据文件信息
SELECT
FILE_ID,
FILE_NAME,
FILE_TYPE,
TABLESPACE_NAME,
FREE_EXTENTS,
TOTAL_EXTENTS,
((TOTAL_EXTENTS - FREE_EXTENTS) * EXTENT_SIZE) / 1024 / 1024 AS MB_used,
EXTENT_SIZE,
INITIAL_SIZE,
MAXIMUM_SIZE,
AUTOEXTEND_SIZE,
DATA_FREE,
STATUS,
ENGINE
FROM
INFORMATION_SCHEMA.FILES;
-- 查看指定表的约束
SELECT
constraint_schema,
table_name,
constraint_name,
column_name,
ordinal_position,
CONCAT(table_name,
'.',
column_name,
' -> ',
referenced_table_name,
'.',
referenced_column_name) AS list_of_fks
FROM
information_schema.KEY_COLUMN_USAGE
WHERE
REFERENCED_TABLE_SCHEMA = 'employees'
AND REFERENCED_TABLE_NAME IS NOT NULL
ORDER BY TABLE_NAME , COLUMN_NAME;
-- 查看指定分区表信息
SELECT
TABLE_SCHEMA,
table_name,
partition_name,
subpartition_name sub_par,
partition_ordinal_position par_position,
partition_method method,
partition_expression expression,
partition_description description,
table_rows
FROM
information_schema.PARTITIONS
WHERE
table_schema = 'test'
AND table_name = 't';
-- 查看支持的插件
SELECT
PLUGIN_NAME, PLUGIN_STATUS, PLUGIN_TYPE,
PLUGIN_LIBRARY, PLUGIN_LICENSE
FROM INFORMATION_SCHEMA.PLUGINS;
SHOW PLUGINS;
-- 查看数据库连接信息
SELECT * FROM INFORMATION_SCHEMA.PROCESSLIST;
SHOW FULL PROCESSLIST;
-- 查看数据库中的存储过程、函数等
SELECT
ROUTINE_SCHEMA,
routine_name,
ROUTINE_TYPE,
data_type,
routine_body,
routine_definition,
routine_comment
FROM
INFORMATION_SCHEMA.ROUTINES
WHERE
ROUTINE_TYPE = 'PROCEDURE'
AND ROUTINE_SCHEMA="employees";
-- 查看存在的数据库及字符集信息
SELECT
SCHEMA_NAME,
DEFAULT_CHARACTER_SET_NAME,
DEFAULT_COLLATION_NAME
FROM
INFORMATION_SCHEMA.SCHEMATA;
SHOW DATABASES;
-- 查看索引信息
SELECT
table_schema,
table_name,
index_name,
COLUMN_NAME,
COLLATION,
CARDINALITY,
index_type
FROM
INFORMATION_SCHEMA.STATISTICS
WHERE
table_name = 'employees'
AND table_schema = 'employees';
SHOW INDEX FROM employees FROM employees;
-- 查看数据库大小
SELECT
table_schema 'database',
CONCAT(ROUND(SUM(data_length + index_length) / (1024 * 1024),
2),
'M') size
FROM
information_schema.TABLES
WHERE
ENGINE in ('MyISAM','InnoDB')
GROUP BY table_schema;
-- 查看表大小
SELECT
CONCAT(table_schema, '.', table_name) table_name,
CONCAT(ROUND(data_length / (1024 * 1024), 2),
'M') data_length,
CONCAT(ROUND(index_length / (1024 * 1024), 2),
'M') index_length,
CONCAT(ROUND(ROUND(data_length + index_length) / (1024 * 1024),
2),
'M') total_size,
engine
FROM
information_schema.TABLES
WHERE
table_schema NOT IN ('information_schema' , 'performance_schema', 'sys', 'mysql')
ORDER BY data_length DESC;
