本文目錄：
一、連接相關
二、長事務
三、元數據鎖
四、鎖等待
五、全局讀鎖
六、內存使用監控
七、分區表
八、數據庫信息概覽
九、長時間未更新的表
十、主鍵、索引
十一、存儲引擎
十二、實時負載
閱讀提示：
1）本篇文章涉及到大量 SQL 語句，在 PC 端閱讀效果更佳。
2）SQL 基於 Oracle MySQL 5.7 版本，其它版本因數據源不同不完全適用。
3）SQL 使用場景包含會話連接、元數據鎖、全局鎖、鎖等待、長事務、內存監控、分區表、低頻更新表、主鍵、索引、存儲引擎、實時負載
一、連接相關
查看某用戶連接的會話級別參數設置及狀態變量，用於觀測其它會話連接行為，輔助定位連接類問題
例：查看用戶連接 ID 為 19 的字符集設置，也可不指定 PROCESSLIST_ID 條件，查看所有用戶連接<code>SELECT T1.VARIABLE_NAME, T1.VARIABLE_VALUE, T2.PROCESSLIST_ID, concat(T2.PROCESSLIST_USER,"@",T2.PROCESSLIST_HOST), T2.PROCESSLIST_DB, T2.PROCESSLIST_COMMANDFROM PERFORMANCE_SCHEMA.VARIABLES_BY_THREAD T1, PERFORMANCE_SCHEMA.THREADS T2WHERE T1.THREAD_ID = T2.THREAD_ID AND T1.VARIABLE_NAME LIKE 'character%' AND PROCESSLIST_ID ='19';+--------------------------+----------------+----------------+-----------------------------------------------------+----------------+---------------------+| VARIABLE_NAME | VARIABLE_VALUE | PROCESSLIST_ID | concat(T2.PROCESSLIST_USER,"@",T2.PROCESSLIST_HOST) | PROCESSLIST_DB | PROCESSLIST_COMMAND |+--------------------------+----------------+----------------+-----------------------------------------------------+----------------+---------------------+| character_set_client | gbk | 19 | root@localhost | db | Query || character_set_connection | gbk | 19 | root@localhost | db | Query || character_set_database | utf8mb4 | 19 | root@localhost | db | Query || character_set_filesystem | binary | 19 | root@localhost | db | Query || character_set_results | gbk | 19 | root@localhost | db | Query || character_set_server | utf8mb4 | 19 | root@localhost | db | Query |+--------------------------+----------------+----------------+-----------------------------------------------------+----------------+---------------------+6 rows in set (0.01 sec)/<code>例：發現用戶 ID 為 254 的連接關閉了 sql_log_bin 設置
<code>SELECT T1.VARIABLE_NAME, T1.VARIABLE_VALUE, T2.PROCESSLIST_ID, concat(T2.PROCESSLIST_USER,"@",T2.PROCESSLIST_HOST) AS 'User@Host', T2.PROCESSLIST_DB, T2.PROCESSLIST_COMMANDFROM PERFORMANCE_SCHEMA.VARIABLES_BY_THREAD T1, PERFORMANCE_SCHEMA.THREADS T2WHERE T1.THREAD_ID = T2.THREAD_ID AND T1.VARIABLE_NAME LIKE 'sql_log_bin';+---------------+----------------+----------------+------------------+----------------+---------------------+| VARIABLE_NAME | VARIABLE_VALUE | PROCESSLIST_ID | User@Host | PROCESSLIST_DB | PROCESSLIST_COMMAND |+---------------+----------------+----------------+------------------+----------------+---------------------+| sql_log_bin | OFF | 254 | root@localhost | NULL | Sleep || sql_log_bin | ON | 256 | root@localhost | NULL | Sleep || sql_log_bin | ON | 257 | root@10.211.55.2 | NULL | Sleep || sql_log_bin | ON | 258 | root@10.211.55.2 | NULL | Sleep || sql_log_bin | ON | 259 | root@localhost | NULL | Query || sql_log_bin | ON | 261 | root@localhost | NULL | Sleep |+---------------+----------------+----------------+------------------+----------------+---------------------+4 rows in set (0.00 sec)/<code>例：查看用戶連接 ID 為 24 的網絡流量變化
<code>SELECT T1.VARIABLE_NAME, T1.VARIABLE_VALUE, T2.PROCESSLIST_ID, concat(T2.PROCESSLIST_USER,"@",T2.PROCESSLIST_HOST) AS 'User@Host', T2.PROCESSLIST_DB, T2.PROCESSLIST_COMMANDFROM PERFORMANCE_SCHEMA.STATUS_BY_THREAD T1, PERFORMANCE_SCHEMA.THREADS T2WHERE T1.THREAD_ID = T2.THREAD_ID AND T2.PROCESSLIST_USER = 'root' AND PROCESSLIST_ID= 24 AND VARIABLE_NAME LIKE 'Byte%';+----------------+----------------+----------------+----------------+----------------+---------------------+| VARIABLE_NAME | VARIABLE_VALUE | PROCESSLIST_ID | User@Host | PROCESSLIST_DB | PROCESSLIST_COMMAND |+----------------+----------------+----------------+----------------+----------------+---------------------+| Bytes_received | 224 | 24 | root@127.0.0.1 | NULL | Sleep || Bytes_sent | 182 | 24 | root@127.0.0.1 | NULL | Sleep |+----------------+----------------+----------------+----------------+----------------+---------------------+2 rows in set (0.00 sec)/<code>
二、長事務
事務開啟後，超過 5s 未提交的用戶連接
<code>SELECT trx_mysql_thread_id AS PROCESSLIST_ID, NOW(), TRX_STARTED, TO_SECONDS(now())-TO_SECONDS(trx_started) AS TRX_LAST_TIME , USER, HOST, DB, TRX_QUERYFROM INFORMATION_SCHEMA.INNODB_TRX trxJOIN INFORMATION_SCHEMA.processlist pcl ON trx.trx_mysql_thread_id=pcl.idWHERE trx_mysql_thread_id != connection_id() AND TO_SECONDS(now())-TO_SECONDS(trx_started) >= 5 ;+----------------+---------------------+---------------------+---------------+------+-----------------+------+-----------+| PROCESSLIST_ID | NOW() | TRX_STARTED | TRX_LAST_TIME | User | Host | DB | TRX_QUERY |+----------------+---------------------+---------------------+---------------+------+-----------------+------+-----------+| 24 | 2019-12-16 02:49:52 | 2019-12-16 02:41:15 | 517 | root | 127.0.0.1:58682 | db | NULL |+----------------+---------------------+---------------------+---------------+------+-----------------+------+-----------+1 row in set (0.01 sec)/<code>
三、元數據鎖
MySQL 5.7 開啟元數據鎖追蹤，以便追蹤定位元數據鎖相關的阻塞問題
<code>// 臨時開啟，動態生效UPDATE performance_schema.setup_consumersSET ENABLED = 'YES'WHERE NAME ='global_instrumentation';UPDATE performance_schema.setup_instrumentsSET ENABLED = 'YES'WHERE NAME ='wait/lock/metadata/sql/mdl';// 配置文件中添加，重啟生效performance-schema-instrument = wait/lock/metadata/sql/mdl=ON/<code>
場景 1：殺掉持有 MDL 鎖的會話，使 DDL 語句順利執行。
<code>// 查找事務運行時間 >= DDL等待時間的線程SELECT trx_mysql_thread_id AS PROCESSLIST_ID, NOW(), TRX_STARTED, TO_SECONDS(now())-TO_SECONDS(trx_started) AS TRX_LAST_TIME , USER, HOST, DB, TRX_QUERYFROM INFORMATION_SCHEMA.INNODB_TRX trxJOIN INFORMATION_SCHEMA.processlist pcl ON trx.trx_mysql_thread_id=pcl.idWHERE trx_mysql_thread_id != connection_id() AND TO_SECONDS(now())-TO_SECONDS(trx_started) >= (SELECT MAX(Time) FROM INFORMATION_SCHEMA.processlist WHERE STATE='Waiting for table metadata lock' AND INFO LIKE 'alter%table%' OR INFO LIKE 'truncate%table%') ;+----------------+---------------------+---------------------+---------------+------+-----------+------+-----------+| PROCESSLIST_ID | NOW() | TRX_STARTED | TRX_LAST_TIME | User | Host | DB | TRX_QUERY |+----------------+---------------------+---------------------+---------------+------+-----------+------+-----------+| 253 | 2019-12-24 01:42:11 | 2019-12-24 01:41:24 | 47 | root | localhost | NULL | NULL |+----------------+---------------------+---------------------+---------------+------+-----------+------+-----------+1 row in set (0.00 sec)// kill掉長事務，釋放持有的MDL資源kill 253;/<code>
注：因 MySQL 元數據信息記錄有限，此處可能誤殺無辜長事務，且誤殺無法完全避免。
當 kill 掉阻塞源後，可能存在 DDL 語句與被阻塞的 SQL 語句同時加鎖的情況，此時會出現事務開始時間等於 DDL 開始時間連接，此類事務也需 kill。<code>//查找事務開始時間 = DDL語句事務開始時間的線程SELECT trx_mysql_thread_id AS PROCESSLIST_ID, NOW(), TRX_STARTED, TO_SECONDS(now())-TO_SECONDS(trx_started) AS TRX_LAST_TIME , USER, HOST, DB, TRX_QUERYFROM INFORMATION_SCHEMA.INNODB_TRX trxJOIN INFORMATION_SCHEMA.processlist pcl ON trx.trx_mysql_thread_id=pcl.idWHERE trx_mysql_thread_id != connection_id() AND trx_started = (SELECT MIN(trx_started) FROM INFORMATION_SCHEMA.INNODB_TRX GROUP BY trx_started HAVING count(trx_started)>=2) AND TRX_QUERY NOT LIKE 'alter%table%' OR TRX_QUERY IS NULL;+----------------+---------------------+---------------------+---------------+------+-----------+------+-----------+| PROCESSLIST_ID | NOW() | TRX_STARTED | TRX_LAST_TIME | User | Host | DB | TRX_QUERY |+----------------+---------------------+---------------------+---------------+------+-----------+------+-----------+| 255 | 2019-12-24 01:42:44 | 2019-12-24 01:42:33 | 11 | root | localhost | NULL | NULL |+----------------+---------------------+---------------------+---------------+------+-----------+------+-----------+1 row in set (0.00 sec)//殺掉阻塞源kill 255;/<code>
場景 2：kill 掉下發 DDL 語句的用戶連接，取消 DDL 語句下發，保障業務不被阻塞。
<code>// 查找DDL語句所在用戶連接SELECT *FROM INFORMATION_SCHEMA.PROCESSLISTWHERE INFO LIKE 'ALTER%TABLE%';+-----+------+-----------+------+---------+------+---------------------------------+----------------------------------+| ID | USER | HOST | DB | COMMAND | TIME | STATE | INFO |+-----+------+-----------+------+---------+------+---------------------------------+----------------------------------+| 254 | root | localhost | NULL | Query | 730 | Waiting for table metadata lock | alter table db.t1 add index (id) |+-----+------+-----------+------+---------+------+---------------------------------+----------------------------------+1 row in set (0.00 sec)// 殺掉DDL語句所在用戶連接kill 254;/<code>
四、鎖等待
查看鎖等待相關的阻塞線程、被阻塞線程信息及相關用戶、IP、PORT
<code>SELECT locked_table, locked_index, locked_type, blocking_pid, concat(T2.USER,'@',T2.HOST) AS "blocking(user@ip:port)", blocking_lock_mode, blocking_trx_rows_modified, waiting_pid, concat(T3.USER,'@',T3.HOST) AS "waiting(user@ip:port)", waiting_lock_mode, waiting_trx_rows_modified, wait_age_secs, waiting_queryFROM sys.x$innodb_lock_waits T1LEFT JOIN INFORMATION_SCHEMA.processlist T2 ON T1.blocking_pid=T2.IDLEFT JOIN INFORMATION_SCHEMA.processlist T3 ON T3.ID=T1.waiting_pid;+--------------+--------------+-------------+--------------+------------------------+--------------------+----------------------------+-------------+-----------------------+-------------------+---------------------------+---------------+---------------------------------+| locked_table | locked_index | locked_type | blocking_pid | blocking(user@ip:port) | blocking_lock_mode | blocking_trx_rows_modified | waiting_pid | waiting(user@ip:port) | waiting_lock_mode | waiting_trx_rows_modified | wait_age_secs | waiting_query |+--------------+--------------+-------------+--------------+------------------------+--------------------+----------------------------+-------------+-----------------------+-------------------+---------------------------+---------------+---------------------------------+| `db`.`t1` | PRIMARY | RECORD | 228 | dks@127.0.0.1:56724 | X | 1 | 231 | root@127.0.0.1:50852 | S | 0 | 1 | insert into db.t1(id) values(2) |+--------------+--------------+-------------+--------------+------------------------+--------------------+----------------------------+-------------+-----------------------+-------------------+---------------------------+---------------+---------------------------------+1 row in set, 3 warnings (0.00 sec)/<code>若不關心阻塞相關的用戶、IP、PORT，可直接查看 innodb_lock_waits 表信息。
<code>select * from sys.x$innodb_lock_waits\\G*************************** 1. row *************************** wait_started: 2019-12-23 02:14:22 wait_age: 00:00:32 wait_age_secs: 32 locked_table: `db`.`t1` locked_index: PRIMARY locked_type: RECORD waiting_trx_id: 7204404 waiting_trx_started: 2019-12-23 02:14:18 waiting_trx_age: 00:00:36 waiting_trx_rows_locked: 1 waiting_trx_rows_modified: 0 waiting_pid: 213 waiting_query: delete from db.t1 where id=200 waiting_lock_id: 7204404:1994:3:4 waiting_lock_mode: X blocking_trx_id: 7204394 blocking_pid: 207 blocking_query: select * from sys.x$innodb_lock_waits blocking_lock_id: 7204394:1994:3:4 blocking_lock_mode: X blocking_trx_started: 2019-12-23 02:10:06 blocking_trx_age: 00:04:48 blocking_trx_rows_locked: 1 blocking_trx_rows_modified: 1 sql_kill_blocking_query: KILL QUERY 207sql_kill_blocking_connection: KILL 2071 row in set, 3 warnings (0.00 sec)/<code>
影響鎖等待超時的參數
五、全局讀鎖
PERFORMANCE_SCHEMA.METADATA_LOCKS 表 LOCK_DURATION 列為 EXPLICIT 狀態表示 FTWRL 語句添加，OBJECT_TYPE 出現 COMMIT 狀態表示已經加鎖成功
場景 1：殺掉添加 FTWRL 的會話，恢復業務運行<code>SELECT processlist_id, mdl.OBJECT_TYPE, OBJECT_SCHEMA, OBJECT_NAME, LOCK_TYPE, LOCK_DURATION, LOCK_STATUSFROM performance_schema.metadata_locks mdlINNER JOIN performance_schema.threads thd ON mdl.owner_thread_id = thd.thread_idAND processlist_id <> connection_id()AND LOCK_DURATION='EXPLICIT';+----------------+-------------+---------------+-------------+-----------+---------------+-------------+| processlist_id | OBJECT_TYPE | OBJECT_SCHEMA | OBJECT_NAME | LOCK_TYPE | LOCK_DURATION | LOCK_STATUS |+----------------+-------------+---------------+-------------+-----------+---------------+-------------+| 231 | GLOBAL | NULL | NULL | SHARED | EXPLICIT | GRANTED || 231 | COMMIT | NULL | NULL | SHARED | EXPLICIT | GRANTED |+----------------+-------------+---------------+-------------+-----------+---------------+-------------+2 rows in set (0.00 sec)// 殺掉添加FTWRL的用戶連接kill 231;/<code>場景 2：殺掉語句執行時間大於 FTWRL 執行時間的線程，確保 FTWRL 下發成功
<code>SELECT T2.THREAD_ID, T1.ID AS PROCESSLIST_ID, T1.User, T1.Host, T1.db, T1.Time, T1.State, T1.Info, T3.TRX_STARTED, TO_SECONDS(now())-TO_SECONDS(trx_started) AS TRX_LAST_TIMEFROM INFORMATION_SCHEMA.processlist T1LEFT JOIN PERFORMANCE_SCHEMA.THREADS T2 ON T1.ID=T2.PROCESSLIST_IDLEFT JOIN INFORMATION_SCHEMA.INNODB_TRX T3 ON T1.id=T3.trx_mysql_thread_idWHERE T1.TIME >= (SELECT MAX(Time) FROM INFORMATION_SCHEMA.processlist WHERE INFO LIKE 'flush%table%with%read%lock') AND Info IS NOT NULL;+-----------+----------------+------+-------------------+------+------+-------------------------+---------------------------------------------+---------------------+---------------+| THREAD_ID | PROCESSLIST_ID | User | Host | db | Time | State | Info | TRX_STARTED | TRX_LAST_TIME |+-----------+----------------+------+-------------------+------+------+-------------------------+---------------------------------------------+---------------------+---------------+| 284 | 246 | root | localhost | NULL | 364 | User sleep | select * from db.t1 where sleep(1000000000) | 2019-12-23 14:57:23 | 364 || 286 | 248 | root | 10.211.55.2:55435 | NULL | 232 | Waiting for table flush | flush table with read lock | NULL | NULL |+-----------+----------------+------+-------------------+------+------+-------------------------+---------------------------------------------+---------------------+---------------+2 rows in set (0.00 sec)/<code>
六、內存使用監控
默認只對 performance_schema 庫進行內存統計，對全局內存統計需要手工開啟
<code>//動態開啟，開啟後開始統計update performance_schema.setup_instruments setenabled = 'yes' where name like 'memory%';//配置文件中添加，重啟生效performance-schema-instrument='memory/%=COUNTED'/<code>查看實例內存消耗分佈，sys 庫下有多張 memory 相關視圖用於協助用戶定位分析內存溢出類問題
<code>SELECT event_name, current_allocFROM sys.memory_global_by_current_bytesWHERE event_name LIKE 'memory%innodb%';+-------------------------------------------+---------------+| event_name | current_alloc |+-------------------------------------------+---------------+| memory/innodb/buf_buf_pool | 134.31 MiB || memory/innodb/log0log | 32.01 MiB || memory/innodb/mem0mem | 15.71 MiB || memory/innodb/lock0lock | 12.21 MiB || memory/innodb/os0event | 8.37 MiB || memory/innodb/hash0hash | 4.74 MiB |...+-------------------------------------------+---------------+42 rows in set (0.01 sec)/<code>
七、分區表
查看實例中的分區表相關信息<code>SELECT TABLE_SCHEMA, TABLE_NAME, count(PARTITION_NAME) AS PARTITION_COUNT, sum(TABLE_ROWS) AS TABLE_TOTAL_ROWS, CONCAT(ROUND(SUM(DATA_LENGTH) / (1024 * 1024), 2),'M') DATA_LENGTH, CONCAT(ROUND(SUM(INDEX_LENGTH) / (1024 * 1024), 2),'M') INDEX_LENGTH, CONCAT(ROUND(ROUND(SUM(DATA_LENGTH + INDEX_LENGTH)) / (1024 * 1024),2),'M') TOTAL_SIZEFROM INFORMATION_SCHEMA.PARTITIONSWHERE TABLE_NAME NOT IN ('sys', 'mysql', 'INFORMATION_SCHEMA', 'performance_schema') AND PARTITION_NAME IS NOT NULLGROUP BY TABLE_SCHEMA, TABLE_NAMEORDER BY sum(DATA_LENGTH + INDEX_LENGTH) DESC ;+--------------+------------------+-----------------+------------------+-------------+--------------+------------+| TABLE_SCHEMA | TABLE_NAME | PARTITION_COUNT | TABLE_TOTAL_ROWS | DATA_LENGTH | INDEX_LENGTH | TOTAL_SIZE |+--------------+------------------+-----------------+------------------+-------------+--------------+------------+| db | t1 | 365 | 0 | 5.70M | 17.11M | 22.81M || db | t2 | 391 | 0 | 6.11M | 0.00M | 6.11M || db | t3 | 4 | 32556 | 2.28M | 0.69M | 2.97M || db | t4 | 26 | 0 | 0.41M | 2.44M | 2.84M || db | t5 | 4 | 0 | 0.06M | 0.00M | 0.06M || db | t6 | 4 | 0 | 0.06M | 0.00M | 0.06M |+--------------+------------------+-----------------+------------------+-------------+--------------+------------+6 rows in set (1.04 sec)/<code>查看某分區表具體信息，此處以庫名為 db、表名為 e 的分區表為例
<code>SELECT TABLE_SCHEMA, TABLE_NAME, PARTITION_NAME, PARTITION_EXPRESSION, PARTITION_METHOD, PARTITION_DESCRIPTION, TABLE_ROWS, 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_SIZEFROM INFORMATION_SCHEMA.PARTITIONSWHERE TABLE_SCHEMA NOT IN ('sys', 'mysql', 'INFORMATION_SCHEMA', 'performance_schema') AND PARTITION_NAME IS NOT NULL AND TABLE_SCHEMA='db' AND TABLE_NAME='e';+--------------+------------+----------------+----------------------+------------------+-----------------------+------------+-------------+--------------+------------+| TABLE_SCHEMA | TABLE_NAME | PARTITION_NAME | PARTITION_EXPRESSION | PARTITION_METHOD | PARTITION_DESCRIPTION | TABLE_ROWS | DATA_LENGTH | INDEX_LENGTH | TOTAL_SIZE |+--------------+------------+----------------+----------------------+------------------+-----------------------+------------+-------------+--------------+------------+| db | e | p0 | id | RANGE | 50 | 4096 | 0.20M | 0.09M | 0.30M || db | e | p1 | id | RANGE | 100 | 6144 | 0.28M | 0.13M | 0.41M || db | e | p2 | id | RANGE | 150 | 6144 | 0.28M | 0.13M | 0.41M || db | e | p3 | id | RANGE | MAXVALUE | 16172 | 1.52M | 0.34M | 1.86M |+--------------+------------+----------------+----------------------+------------------+-----------------------+------------+-------------+--------------+------------+4 rows in set (0.00 sec)/<code>
八、數據庫信息概覽
統計實例中各數據庫大小<code>SELECT TABLE_SCHEMA, round(SUM(data_length+index_length)/1024/1024,2) AS TOTAL_MB, round(SUM(data_length)/1024/1024,2) AS DATA_MB, round(SUM(index_length)/1024/1024,2) AS INDEX_MB, COUNT(*) AS TABLESFROM INFORMATION_SCHEMA.tablesWHERE TABLE_SCHEMA NOT IN ('sys', 'mysql', 'INFORMATION_SCHEMA', 'performance_schema')GROUP BY TABLE_SCHEMAORDER BY 2 DESC;+--------------+----------+---------+----------+--------+| TABLE_SCHEMA | TOTAL_MB | DATA_MB | INDEX_MB | TABLES |+--------------+----------+---------+----------+--------+| cloud | 229.84 | 223.02 | 6.83 | 41 || db | 66.42 | 30.56 | 35.86 | 31 || dks | 14.41 | 9.70 | 4.70 | 621 || test | 0.06 | 0.06 | 0.00 | 4 || db2 | 0.03 | 0.03 | 0.00 | 2 |+--------------+----------+---------+----------+--------+5 rows in set, 1 warning (0.91 sec)/<code>統計某庫下各表大小
<code>SELECT 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, engineFROM INFORMATION_SCHEMA.TABLESWHERE TABLE_SCHEMA NOT IN ('INFORMATION_SCHEMA' , 'performance_schema', 'sys', 'mysql') AND TABLE_SCHEMA='db'ORDER BY (data_length + index_length) DESC LIMIT 10;+--------------+-----------------------+-------------+--------------+------------+--------+| TABLE_SCHEMA | table_name | data_length | index_length | total_size | engine |+--------------+-----------------------+-------------+--------------+------------+--------+| db | t1 | 5.70M | 22.81M | 28.52M | InnoDB || db | t2 | 15.19M | 9.59M | 24.78M | InnoDB || db | t3 | 6.11M | 0.00M | 6.11M | InnoDB || db | t4 | 2.28M | 0.69M | 2.97M | InnoDB || db | t5 | 0.41M | 2.44M | 2.84M | InnoDB || db | t6 | 0.17M | 0.00M | 0.17M | InnoDB || db | t7 | 0.17M | 0.00M | 0.17M | InnoDB || db | t8 | 0.02M | 0.11M | 0.13M | InnoDB || db | t9 | 0.08M | 0.00M | 0.08M | InnoDB || db | t10 | 0.05M | 0.02M | 0.06M | InnoDB |+--------------+-----------------------+-------------+--------------+------------+--------+10 rows in set, 1 warning (0.01 sec)/<code>查看某庫下表的基本信息
<code>SELECT TABLE_SCHEMA, TABLE_NAME, table_collation, engine, table_rowsFROM INFORMATION_SCHEMA.tablesWHERE TABLE_SCHEMA NOT IN ('INFORMATION_SCHEMA' , 'sys', 'mysql', 'performance_schema') AND TABLE_TYPE='BASE TABLE' AND TABLE_SCHEMA='db'ORDER BY table_rows DESC ;+--------------+-----------------------+--------------------+--------+------------+| TABLE_SCHEMA | table_name | table_collation | engine | table_rows |+--------------+-----------------------+--------------------+--------+------------+| db | t1 | utf8_general_ci | InnoDB | 159432 || db | t2 | utf8mb4_general_ci | InnoDB | 32556 || db | t3 | utf8mb4_general_ci | InnoDB | 2032 |...| db | t100 | utf8mb4_general_ci | InnoDB | 0 || db | t101 | utf8mb4_general_ci | InnoDB | 0 |+--------------+-----------------------+--------------------+--------+------------+25 rows in set, 1 warning (0.01 sec)/<code>
九、長時間未更新的表
UPDATE_TIME 為 NULL 表示實例啟動後一直未更新過
<code>SELECT TABLE_SCHEMA, TABLE_NAME, UPDATE_TIMEFROM INFORMATION_SCHEMA.TABLESWHERE TABLE_SCHEMA NOT IN ('SYS', 'MYSQL', 'INFORMATION_SCHEMA', 'PERFORMANCE_SCHEMA') AND TABLE_TYPE='BASE TABLE'ORDER BY UPDATE_TIME ;+--------------+-----------------------+---------------------+| TABLE_SCHEMA | TABLE_NAME | UPDATE_TIME |+--------------+-----------------------+---------------------+| db | t1 | NULL || db | t2 | NULL || db | t3 | NULL || db | t4 | 2019-12-16 07:45:29 || db | t5 | 2019-12-16 16:52:01 |+--------------+-----------------------+---------------------+22 rows in set, 1 warning (0.01 sec)/<code>
十、主鍵、索引
無主鍵、唯一鍵及二級索引基表
MySQL Innodb 存儲引擎為索引組織表，因此設置合適的主鍵字段對性能至關重要<code>SELECT T1.TABLE_SCHEMA, T1.TABLE_NAMEFROM INFORMATION_SCHEMA.COLUMNS T1 JOIN INFORMATION_SCHEMA.TABLES T2 ON T1.TABLE_SCHEMA=T2.TABLE_SCHEMA AND T1.TABLE_NAME=T2.TABLE_NAMEWHERE T1.TABLE_SCHEMA NOT IN ('SYS', 'MYSQL', 'INFORMATION_SCHEMA', 'PERFORMANCE_SCHEMA') AND T2.TABLE_TYPE='BASE TABLE' AND T1.TABLE_SCHEMA='db'GROUP BY T1.TABLE_SCHEMA, T1.TABLE_NAME HAVING MAX(COLUMN_KEY)='';/<code>
無主鍵、唯一鍵，僅有二級索引表
該類型表因無高效索引，因此從庫回放時容易導致複製延遲<code>SELECT T1.TABLE_SCHEMA, T1.TABLE_NAMEFROM INFORMATION_SCHEMA.COLUMNS T1 JOIN INFORMATION_SCHEMA.TABLES T2 ON T1.TABLE_SCHEMA=T2.TABLE_SCHEMA AND T1.TABLE_NAME=T2.TABLE_NAMEWHERE T1.TABLE_SCHEMA NOT IN ('SYS', 'MYSQL', 'INFORMATION_SCHEMA', 'PERFORMANCE_SCHEMA') AND T2.TABLE_TYPE='BASE TABLE' AND T1.COLUMN_KEY != ''GROUP BY T1.TABLE_SCHEMA, T1.TABLE_NAME HAVING group_concat(COLUMN_KEY) NOT REGEXP 'PRI|UNI';/<code>
僅有主鍵、唯一鍵表
該類型表結構因無二級索引，可能導致應用 SQL 語句上線後頻繁全表掃描出現性能抖動<code>SELECT T1.TABLE_SCHEMA, T1.TABLE_NAMEFROM INFORMATION_SCHEMA.COLUMNS T1 JOIN INFORMATION_SCHEMA.TABLES T2 ON T1.TABLE_SCHEMA=T2.TABLE_SCHEMA AND T1.TABLE_NAME=T2.TABLE_NAMEWHERE T1.TABLE_SCHEMA NOT IN ('SYS', 'MYSQL', 'INFORMATION_SCHEMA', 'PERFORMANCE_SCHEMA') AND T2.TABLE_TYPE='BASE TABLE' AND T1.COLUMN_KEY != '' AND T1.TABLE_SCHEMA='db'GROUP BY T1.TABLE_SCHEMA, T1.TABLE_NAME HAVING group_concat(COLUMN_KEY) NOT REGEXP 'MUL';/<code>
無主鍵、唯一鍵表
<code>SELECT T1.TABLE_SCHEMA, T1.TABLE_NAMEFROM INFORMATION_SCHEMA.COLUMNS T1 JOIN INFORMATION_SCHEMA.TABLES T2 ON T1.TABLE_SCHEMA=T2.TABLE_SCHEMA AND T1.TABLE_NAME=T2.TABLE_NAMEWHERE T1.TABLE_SCHEMA NOT IN ('SYS', 'MYSQL', 'INFORMATION_SCHEMA', 'PERFORMANCE_SCHEMA')AND T2.TABLE_TYPE='BASE TABLE'GROUP BY T1.TABLE_SCHEMA, T1.TABLE_NAME HAVING group_concat(COLUMN_KEY) NOT REGEXP 'PRI|UNI';/<code>
十一、存儲引擎
存儲引擎分佈<code>SELECT TABLE_SCHEMA, ENGINE, COUNT(*)FROM INFORMATION_SCHEMA.TABLESWHERE TABLE_SCHEMA NOT IN ('INFORMATION_SCHEMA' , 'PERFORMANCE_SCHEMA', 'SYS', 'MYSQL') AND TABLE_TYPE='BASE TABLE'GROUP BY TABLE_SCHEMA, ENGINE;/<code>非 INNODB 存儲引擎表
<code>SELECT TABLE_SCHEMA, TABLE_NAME, TABLE_COLLATION, ENGINE, TABLE_ROWSFROM INFORMATION_SCHEMA.TABLESWHERE TABLE_SCHEMA NOT IN ('INFORMATION_SCHEMA' , 'SYS', 'MYSQL', 'PERFORMANCE_SCHEMA') AND TABLE_TYPE='BASE TABLE' AND ENGINE NOT IN ('INNODB')ORDER BY TABLE_ROWS DESC ;/<code>
十二、實時負載
<code>while truedomysqladmin -uroot -pxxxxxxx extended-status -r -i 1 -c 30 --socket=/mysqldata/mysqld.sock 2>/dev/null|awk -F"|" "BEGIN{ count=0 ;}"'{ if($2 ~ /Variable_name/ && ++count == 1){\\ print "----------|---------|--- MySQL Command Status --|----- Innodb row operation ----|-- Buffer Pool Read --";\\ print "---Time---|---QPS---|select insert update delete| read inserted updated deleted| logical physical";\\}\\else if ($2 ~ /Queries/){queries=$3;}\\else if ($2 ~ /Com_select /){com_select=$3;}\\else if ($2 ~ /Com_insert /){com_insert=$3;}\\else if ($2 ~ /Com_update /){com_update=$3;}\\else if ($2 ~ /Com_delete /){com_delete=$3;}\\else if ($2 ~ /Innodb_rows_read/){innodb_rows_read=$3;}\\else if ($2 ~ /Innodb_rows_deleted/){innodb_rows_deleted=$3;}\\else if ($2 ~ /Innodb_rows_inserted/){innodb_rows_inserted=$3;}\\else if ($2 ~ /Innodb_rows_updated/){innodb_rows_updated=$3;}\\else if ($2 ~ /Innodb_buffer_pool_read_requests/){innodb_lor=$3;}\\else if ($2 ~ /Innodb_buffer_pool_reads/){innodb_phr=$3;}\\else if ($2 ~ /Uptime / && count >= 2){\\ printf(" %s |%9d",strftime("%H:%M:%S"),queries);\\ printf("|%6d %6d %6d %6d",com_select,com_insert,com_update,com_delete);\\ printf("|%6d %8d %7d %7d",innodb_rows_read,innodb_rows_inserted,innodb_rows_updated,innodb_rows_deleted);\\ printf("|%10d %11d\\n",innodb_lor,innodb_phr);\\}}'done/<code>