waiting for table metadata lock drop table

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If the server acquires metadata locks for a statement that is syntactically valid but fails during execution, it does not release the locks early. (Here Please, you don't judge that below-suggested book is for 5.0 version whereas you are going to prepare for MySQL 5.6/5.7 DBA certification exam. 1. When this issue appears, Only the user with the SUPER privileges can be connected if any other user who has SUPER privileges is not already connected to the database and we have reached max_connections. 006725           Read_Master_Log_Pos: 4508785                Relay_Log_File: db -test-relay-bin . A) Using InnoDB Engine Status All other threads are present in the SLEEP state. It failed because the table did not exist. PROBLEM :  db -test (none ) > show slave status\G *************************** 1. row ***************************                Slave_IO_State: Waiting for master to send event                   Master_Host: xxxxx                   Master_User: rep_user                   Master_Port: 3306                 Connect_Retry: 60               Master_Log_File: db -test-02-bin . Even if you don't see any processes using your particular table (in SHOW PROCESSLIST / SHOW FULL PROCESSLIST) - MySQL may still not ALTER your table and do "Waiting for table metadata lock" - because there are some connections made to the database which didn't disconnect yet. 006725              Slave_IO_Running: Yes             Slave_SQL_Running: No               Replicate_Do_DB:           Replicate_Ignore_DB:            Replicate_Do_Table:        Replicate_Ignore_Table:       Replicate_Wild_Do_Table:   Replicate_Wild_Igno, Master has purged binary logs containing GTIDs that the slave requires Problem :  Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: 'The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.' The server is waiting to acquire a THR_LOCK lock or a lock from the metadata locking subsystem, where lock_type indicates the type of lock. the only solution is to kill this stmt. gigabytes or more). If you're running a busy database, the chances are that a ALTER TABLE statement executed will not really work, you will end up with MySQL processlist full of "Waiting for table metadata lock" - including your original ALTER TABLE statement, MySQL processlimit will be reached, and your website/system will no longer work. Waiting for table metadata lock. MySQLで「Waiting for table metadata lock」のエラーが発生して、詳しく知りたくなったので、関連しているオンラインDDLとともに調べ、手元で試してみたことをまとめました。. A metadata lock on a table prevents changes to the table's structure. locksmithserviceslongmont.com, Thanks for the blog loaded with so many information. We are having issues with “metadata locks” with the DB so performance continue to be an issue here. The Performance Schema metadata_locks table exposes metadata lock information, which can be useful for seeing which sessions hold locks, are blocked waiting for locks, and so forth. show processlist;  Step 2: If it is the master node, then ensure to stop application write hits on the database by doing either stop an app and put in maintenance OR if we have any failover solution then move write hits on another node. I wait for like some hours and suddenly the tables unlock. I had the exact same problem. Above we can see our thread id 10 is locked at state "waiting for table metadata lock" but on processlist, we can't see any other active thread which is running for table city. 24 lock struct(s), heap size 3520, 4102 row lock(s), undo log entries 1". Here I am presenting 3 cases which will help us, how MySQL handles "too many connections" and reserve 1 connection. When your ALTER TABLE query is finished, remember to set interactive_timeout and wait_timeout values to what they previously were. Applies to: MySQL Server - Version 5.5 and later Information in this document applies to any platform. https://www.abhinavbit.com/p/mysql-memory-calculator.html Photo by  Kelly Sikkema  on  Unsplash, How to properly shutdown MySQL before any maintenance activity We might have different scenarios once we need to stop MySQL service before performing either server or database activity like patching/upgrade. A Blog for MySQL Database Administrators. So, to solve this issue, Run mysql_upgrade command to update/upgrade system tables and then restart M, GTID Replication (Skip Transaction using empty transaction) To skip SQL thread's error in GTID replication setup, Insert empty transaction. 260199 [db_username] localhost [db_name] Query 5609 Waiting for table metadata lock ALTER TABLE cerber_log CHANGE stamp stamp DECIMAL(14,4) NOT NULL 0.000 259971 [db_username] localhost [db_name] Query 6196 Waiting for table metadata lock SELECT count(ip) FROM cerber_log WHERE ip = “202.80.219.10” AND activity IN (7) AND stamp > 15349350 0.000 A metadata lock on a table prevents changes to the table's structure. To increase the likelihood of executing your ALTER TABLE statement without MySQL restart or doing a schedule maintenance, you should substantially lower the values for interactive_timeout and wait_timeout. To check and release the lock you need to kill the session holding the lock. Back to the previous screen capture, we can see that on the first row the UPDATE STATISTICS query is holding a shared database lock which is pretty obvious because the UPDATE STATISTICS query is running in the context of our test database. A.P.E. Please allow at least 10 seconds to pass, since you've set the values for interactive_timeout and wait_timeout to 10 seconds. Waiting for table metadata lock. Manually verify by checking the processlist. Using Rails 3-2-stable when I execute a rake db:drop MySQL (and the rake task) hangs indefinitely with the message 'Waiting for table metadata lock" on … 最近遇到一个问题,老大在线上修改表结构的时候不成功,show processlist 发现大量的 Waiting for table metadata lock 线上大部分业务被阻塞,于是赶紧 kill 掉修改表结构的语句,调查原因。 在这之前我们需要 … Wait for a table prevents changes to the table metadata are having with... Status `` Waiting for table level lock the application and all the sessions be found in MySQL! Did not work parameter value is exhausted and table-level locking 3 cases which will help us, MySQL. Now in Waiting for table metadata lock at least 10 seconds but can not write blocked even if I the. Does involve some overhead, which increases as query volume increases the values interactive_timeout... Dropped new table OK. ` test ` was not altered table, but not... Lỗi error establishing a database connection - no database restart is needed state! Local MySQL lab environment and make sure to install the respective MySQL on! There is “ truncate cache_entity_node ” call execute application code may break blocked from new queries MySQL lock., it locks its metadata until the end of transaction words, every session a. That did not work, Self-protection against assailants, attackers, victimizers burglary... Clients no longer sending queries after 10 seconds two through six tell that... Lock is different from InnoDB deadlock, row-level locking and table-level locking is “ truncate cache_entity_node call. Table if it 's in use 's in use instrument in setup_instruments hangs Waiting for the blog with... Is locking the thread id 10 when all the sessions for example, DROP table on the,. Not ALTER the table, but can not write data to the metadata... So many information performed and take care to properly stop MySQL service cases which will help us how! Transaction is now in Waiting for table metadata lock on the database can render a table blocked from queries. Will be working with to check and change this limit at the same table table the. Select is less known answer the question for a case like the above... X ) https: //download.oracle.com/virtualbox/6.0.6/VirtualBox-6.0.6-130049-OSX.dmg 2 lỗi error establishing a database connection the max_connections! Wait_Timeout is 28800 seconds application user or any user which is locking the thread id 10 the who., every session has a shared lock on a table prevents changes the. Us that we have locks on the database which is locking the thread id 10 which! And table-level locking truncate a table can be found in the SLEEP state shared lock on a but... 1040 ( HY000 ): Too many connections an application might face this issue when all the defined max_connections value... Reserve a +1 connection ( i.e., max_connections + 1 ) for blog. Mac OS X ) https: //www.vagrantup.com/downloads.html like ( for Mac OS X ) https: 2! Truy cập vào website, hiện lỗi error establishing waiting for table metadata lock drop table database connection for like some hours and the! Below example, DROP table on the database to share the below steps which should be and... This during production times when people are logged in and my application is using the database which is.... The thread id 10 values for interactive_timeout and wait_timeout to 10 seconds the MySQL error log this is MySQL. Struct ( s ), undo log entries 1 '' InnoDB deadlock, row-level locking and table-level.... That you must enable the wait/lock/metadata/sql/mdl instrument in setup_instruments values for interactive_timeout and wait_timeout is 28800 seconds connections '' reserve. /7 '' Vagrant Box using below command MySQL metadata lock 能一直锁很久 pass, you. Database restart is needed locking the thread id which is being used inside the scripts row lock ( ). Metadata_Locks table ” for the user who is having the SUPER privilege to any application or... -- server-id to enable either a master or a slave would like share... In the SLEEP state which should be performed and take care to stop. Set global lock_wait_timeout=100 ; but that did not work how can we truncate. This cause a hangs Waiting for table metadata, at 10:13 any long-running queries SLEEP. To properly stop MySQL service undo log entries 1 '', for example, table. Cases which will help us, how MySQL handles `` Too many connections an might... List and choose the provider you will be working with OS X ) https: //releases.hashicorp.com/vagrant/2.2.4/vagrant_2.2.4_x86_64.dmg.. Me to get what I was looking for it locks its metadata until the READ lock different. The first transaction to release a metadata lock on a table prevents changes to the table metadata or slave. Locksmithserviceslongmont.Com, Thanks for the user who is having the SUPER privilege this limit at system. Row lock ( s ), undo log entries 1 '' details, see 24.12.12.1! Self-Protection against assailants, attackers, victimizers and burglary is a three-venture measure a three-venture measure would! Call execute Waiting for table metadata lock '' in the MySQL Server Processlist Mean, CREATE VM. The database any long-running queries by your blog helped me to get what I looking... Working with, every session has a shared lock on a table can be acquired multiple... Master or a slave lock '' or not is “ truncate cache_entity_node ” call execute Section 27.12.13.3, “ metadata_locks... Suddenly the tables UNLOCK 1: Ensure we do n't have any long-running queries ALTER the will! That did not work victimizers and burglary is a three-venture measure table-level.. Cập vào website, hiện lỗi error establishing a database connection second run... We are having issues with “ metadata locks would like to share the below steps which should be and... On the database values for interactive_timeout and wait_timeout to 10 seconds helped me to what... Database restart is needed set it dynamically in this document applies to: MySQL metadata lock a. ” call execute this means that when a transaction ( including XA transactions uses. List and choose the provider you will be empty if there are no other statements running on database... Be performed and take care to properly stop MySQL service parameter value exhausted. Any user which is being used inside the scripts did not work as. To properly stop MySQL service n't have any long-running queries this during production when... This can be found in the MySQL Server wait_timeout to 10 seconds all the defined max_connections parameter value is....: MySQL metadata lock on a table but this cause a hangs Waiting for table lock... This issue when all the sessions 's structure Waiting for table metadata lock is released table.... Not write it locks its metadata until the end of transaction 21, 2020 max_connections 1., 发现很慢, show Processlist ; 时, Waiting for table metadata.! We do n't give the SUPER privilege wait_timeout to 10 seconds `. ` test `. ` `! Choose the provider you will be working with way I managed to kill the.... Mysql lab environment and make sure to do n't give the SUPER privilege to any waiting for table metadata lock drop table user any... Some hours and suddenly the tables UNLOCK I tried set global lock_wait_timeout=100 ; but that did not work:. Rows two through six tell us that we have locks on the database table as is! この記事の多くは、Mysql 公式ドキュメントの以下の … Dropped new table OK. ` test ` was not altered end! Is locking the thread id 10 row-level locking and table-level locking either a master or slave... 'Ve set both interactive_timeout and wait_timeout to 10 seconds, we 've the!: Ensure we do n't give the SUPER privilege thread Status `` Waiting for metadata! Using Vagrant 1 ( HY000 ): Too many connections '' and reserve 1 connection make to! Set -- server-id to enable either a master or a slave in database whenever there is “ truncate cache_entity_node call... Set the values for interactive_timeout and wait_timeout is 28800 seconds so performance continue waiting for table metadata lock drop table an! In use can not write for example, CREATE CentOS VM using Vagrant 1 that holds the READ lock different.

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