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. Please note: MySQL metadata lock is different from InnoDB deadlock, row-level locking and table-level locking. gigabytes or more). the only solution is to kill this stmt. Here the steps executed: mysql> SELECT * FROM performance_schema.MUTEX_INSTANCES WHERE LOCKED_BY_THREAD_ID IS NOT NULL; Empty set (0.00 sec) mysql> SELECT * FROM performance_schema.RWLOCK_INSTANCES WHERE … Just go ahead and purchase below book. How to Identify SID Based on OS PID in Oracle Query to Check Table Lock in Oracle Database A metadata lock on a table prevents changes to the table's structure. Download " centos /7" Vagrant Box using below command. This page was last modified on 17 October 2016, at 10:13. Rows two through six tell us that we have locks on the table metadata. Update. This can be used to answer the question for a case like the one above. 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. Changing back interactive_timeout and wait_timeout … Please allow at least 10 seconds to pass, since you've set the values for interactive_timeout and wait_timeout to 10 seconds. If you no longer see "Waiting for table metadata lock" - good luck, it should finish soon (assuming that the table you're changing is not very large, i.e. For details, see Section 27.12.13.3, “The metadata_locks Table” . 在修改/增加表字段的时候,发现很慢, show processlist; 时, Waiting for table metadata lock 能一直锁很久. A READ lock has the following features:. I wait for like some hours and suddenly the tables unlock. Very well explained in simple words, really helps!Thanks!Rohan, A private locksmith will enable you to choose what kinds of locks you requirement for all the windows and entryways in your home. This state indicates a wait for a THR_LOCK : Waiting for table level lock この記事の多くは、MySQL 公式ドキュメントの以下の … Download and install the latest Vagrant. And other sessions cannot write data to the table until the READ lock is released. Description: I'm trying truncate a table but this cause a hangs Waiting for table metadata lock. mysql [localhost:5726] {msandbox} (world) > show engine innodb status\G, Purge done for trx's n:o < 1875 undo n:o < 0 state: running but idle, ---TRANSACTION 421869282924072, not started, 0 lock struct(s), heap size 1136, 0 row lock(s), ---TRANSACTION 421869282922944, not started, ---TRANSACTION 421869282921816, not started, , OS thread handle 140394578265856, query id 5478 localhost msandbox. abhinavs -Air : ~ agupta$ vagrant box add centos /7 ==> box: Loading metadata for box ' centos /7'      box : URL: https://vagrantcloud.com/centos/7 This box can work with multiple providers! mysqld reserve a  +1 connection (i.e., max_connections + 1) for the user who is having the SUPER privilege. I tried set global lock_wait_timeout=100; but that did not work. “Waiting for table metadata lock” occurs in database whenever there is “truncate cache_entity_node” call execute. This locking approach has the implication that a table that is being used by a transaction within one session cannot be used in DDL statements by other sessions until the transaction ends. 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. 1) hyperv 2) libvirt 3) virtualbox 4) vmware_desktop Enter your choice: 3 ==> box: Addin, How to Prepare for MySQL Certification Exam Here I am going to suggest MySQL DBA, student or any newbie that how they can prepare for "Oracle's MySQL 5.x Database Administrator" certification exam. There is a new Performance Schema table metadata_locks which will tell which metadata locks are held and which are pending. (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. Dropped new table OK. `test`.`test` was not altered. Solution :- Here It is assumed, We have already set server-id parameter value different on master and slave node but still, we have the above error. Not exist other transactions working on this table. Here I would like to share the below steps which should be performed and take care to properly stop MySQL service. How to Identify SID Based on OS PID in Oracle Query to Check Table Lock in Oracle Database (More information about the metadata locking in general). Metadata lock issue. represents Awareness, Protection and Escape. 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 . Based on the issue tied to the patch your comment, I am adding more info to my answer: Looking over Waiting for table metadata lock on cache_field table, the earlier patch in #3 gave way to an updated patch in #26. MariaDB supports metadata locking. It failed because the table did not exist. root@test:~# ulimit -a core file size          (blocks, -c) 0 data seg size           (kbytes, -d) unlimited scheduling priority             (-e) 0 file size               (blocks, -f) unlimited pending signals                 (-i) 515256 max locked memory       (kbytes, -l) 64 max memory size         (kbytes, -m) unlimited open files                      (-n) 1024 pipe size            (512 bytes, -p) 8 POSIX message queues     (bytes, -q) 819200 real-time priority              (-r) 0 stack size. (Doc ID 1365549.1) Last updated on OCTOBER 21, 2020. 000015                 Relay_Log_Pos: 2146333         Relay_Master_Log_File: db -test-02-bin . All other threads are present in the SLEEP state. The ideal solution would be to let the user specify lock_wait_timeout via another variable metadata_lock_wait_timeout, and let the user specify the number of retries to be done when metadata locks cannot be taken immediately via another variable metadat_lock_retries perhaps. --> To check and change this limit at the system level, we use ulimit client tool to set it dynamically. Here I am going to focus on one of the scenarios when db connection threads are locked at state ", Hope this blog post will help to troubleshoot the ", MySQL Memory Calculator Check out the “ MySQL Memory Calculator ” added to my blog page, which will be helpful to calculate MySQL memory usage during tuning of MySQL memory parameters. The session that holds the READ lock can only read data from the table, but cannot write. In a previous article, Ovais demonstrated how a DDL can render a table blocked from new queries. – Haluk Jul 27 '12 at 21:48 To check and release the lock you need to kill the session holding the lock. ERROR 1040 (HY000): Too many connections An application might face this issue when all the defined max_connections parameter value is exhausted. They can be overridden in MySQL config file (my.cnf) for example with: If you're not sure what they currently are, you can always check it with: To change interactive_timeout and wait_timeout, use: After that, in most cases, your ALTER TABLE query will execute without getting "Waiting for table metadata lock". For details, see Section 24.12.12.1, “The metadata_locks Table” . 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. 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. the stmt is in a state of "Waiting for table metadata lock" It never recovers from this and just hangs. But I hope this gives you some direction toward solving your locking issue. 私はテーブル上でいくつかのDDLを実行しようとしており、 SHOW PROCESSLIST結果は "Waiting for table metadata lock"というメッセージになります。 どの取引がまだ終了していないかを知るにはどうすればよいですか? 私はMySQL v5.5.24を使用しています。 In other words, every session has a shared lock on the database which is running. Please review the list and choose the provider you will be working with. A.P.E. Manually verify by checking the processlist. The second transaction is now in waiting for the first transaction to release a metadata lock. 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. From lxadm | Linux administration tips, tutorials, HOWTOs and articles, Verifying if ALTER TABLE is still hanging, https://lxadm.com/index.php?title=MySQL:_avoiding_%22Waiting_for_table_metadata_lock%22_when_executing_%22ALTER_TABLE%22&oldid=361, GNU Free Documentation License 1.3 or later, About lxadm | Linux administration tips, tutorials, HOWTOs and articles. A Blog for MySQL Database Administrators. 24 lock struct(s), heap size 3520, 4102 row lock(s), undo log entries 1". In addition, other sessions can read data from the table without acquiring the lock. mysql [localhost:5726] {msandbox} ((none)) > kill 17; mysql [localhost:5726] {msandbox} (world) > alter table city engine=innodb; Query OK, 0 rows affected (26 min 8.17 sec), How to properly shutdown MySQL before any maintenance activity, How to Prepare for MySQL Certification Exam, set --server-id to enable either a master or a slave, GTID Replication (Skip Transaction using empty transaction), Master has purged binary logs containing GTIDs that the slave requires. 在进行alter table操作时,有时会出现Waiting for table metadata lock的等待场景.而且,一旦alter table TableA的 ... alter table锁表,MySQL出现Waiting for table metadata lock的场景浅析及解决方案. What Does Thread Status "Waiting for table metadata lock" in the MySQL Server Processlist Mean? When your ALTER TABLE query is finished, remember to set interactive_timeout and wait_timeout values to what they previously were. Kind of like importing the table. check now. https://www.oracle.com/technetwork/server-storage/virtualbox/downloads/index.html Like (For Mac OS X) https://download.oracle.com/virtualbox/6.0.6/VirtualBox-6.0.6-130049-OSX.dmg 2. The only way I managed to kill the lock was to restart the mysql server. 1. mysql [localhost:5726] {msandbox} (information_schema) > select ps.id,ps.user,ps.host,ps.db,ps.command from information_schema.processlist ps join information_schema.INNODB_TRX itx on itx.trx_mysql_thread_id=ps.id and ps.command='Sleep'; +----+----------+-----------+-------+---------+, | id | user     | host      | db    | command |, | 17 | msandbox | localhost | world | Sleep   |, mysql [localhost:5726] {msandbox} ((none)) > SELECT   pslst.id 'PROCESS ID'  ,itrx.trx_id 'TRX_ID'     ,pesh.event_name 'EVENT NAME'     ,pesh.sql_text 'SQL'     ,th.processlist_user 'USER'     ,th.processlist_host 'HOST' FROM   information_schema.innodb_trx itrx JOIN information_schema.processlist pslst ON   itrx.trx_mysql_thread_id = pslst.id JOIN performance_schema.threads th ON   th.processlist_id = itrx.trx_mysql_thread_id JOIN performance_schema.events_statements_history pesh ON   pesh.thread_id = th.thread_id WHERE   itrx.trx_started < CURRENT_TIME - INTERVAL 100 SECOND  AND pslst.USER != 'SYSTEM_USER' GROUP BY  pesh.sql_text ORDER BY   pesh.EVENT_ID\G, *************************** 7. row ***************************, mysql [localhost:5726] {msandbox} ((none)) >. 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 … Additional error messages can be found in the MySQL error log. https://www.vagrantup.com/downloads.html Like (For Mac OS X) https://releases.hashicorp.com/vagrant/2.2.4/vagrant_2.2.4_x86_64.dmg 3. and myisam tables somehow get stuck with a metadata lock. there are NO other statements running on the database. 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. We are having issues with “metadata locks” with the DB so performance continue to be an issue here. Solution : stop slave; Query OK, 0 rows affected (0.00 sec) CHANGE MASTER TO MASTER_AUTO_POSITION = 0; Query OK, 0 rows affected (0.01 sec) start slave; Query OK, 0 rows affected (0.00 sec), mysql [localhost:5726] {msandbox} (world) > show processlist\G, *************************** 1. row ***************************, State: Master has sent all binlog to slave; waiting for more updates, *************************** 2. row ***************************, *************************** 3. row ***************************, *************************** 4. row ***************************, *************************** 5. row ***************************, *************************** 6. row ***************************, mysql [localhost:5726] {msandbox} (world) >. READ Locks. I had the exact same problem. MySQLのバージョンは 5.6、ストレージエンジンは InnoDB です。. The application code may break. Waiting for table metadata lock. 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. I do this during production times when people are logged in and my application is using the database. 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 … (i.e., if you are going to appear on MySQL 5.6 DBA exam 1Z0-883 then install MySQL 5.6 on your lab)  -- You can follow my below blog post to create your local MySQL lab environment. Please allow at least 10 seconds to pass, since you've set the values for interactive_timeout and wait_timeout to 10 seconds. AAA Locksmith Seattle, Self-protection against assailants, attackers, victimizers and burglary is a three-venture measure. Always make sure to DON'T give the SUPER privilege to any application user or any user which is being used inside the scripts. 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 … You should see if it has "Waiting for table metadata lock" or not. MySQL thread id 3511, OS thread handle 0x2ba8c4ebf700, query id 1077780 a83-161-215-203.adsl.xs4all.nl 83.161.215.203 root Waiting for table metadata lock DROP TABLE IF EXISTS pred_orders_table ---TRANSACTION 0, not started gigabytes or more). For details, see Section 24.12.12.1, “The metadata_locks Table”. How can we disable truncate action on entitycache module ? 006725           Read_Master_Log_Pos: 4508785                Relay_Log_File: db -test-relay-bin . In the end, you will definitely say it was your, set --server-id to enable either a master or a slave Below issue can be faced, when we run CHANGE MASTER command to setup replication. For below example, Create CentOS VM using Vagrant 1. Sometimes they remain blocked even if I kill the application and all the sessions. Applies to: MySQL Server - Version 5.5 and later Information in this document applies to any platform. Before performing such activity, we need to make sure that we stop MySQL service properly to avoid any unforeseen crashes once our maintenance activity complete and MySQL service is started. 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. 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.' These values can be changed dynamically - no database restart is needed. First instrumentation of metadata locks should be enabled. Yes, the second transaction is waiting for a lock hold on a non-existing table, if you are using MySQL 5.5.3 or higher… If you no longer see "Waiting for table metadata lock" - good luck, it should finish soon (assuming that the table you're changing is not very large, i.e. In a previous article, Ovais demonstrated how a DDL can render a table blocked from new queries. For some time it works but suddenly some tables are locked and my sessions with DDL/DML on them hang with "waiting for table metadata lock". Metadata lock issue for CREATE TABLE AS SELECT is less known. I tried flushing tables and UNLOCK tables with no result. * Check current system open file limit. In another article, Valerii introduced performance_schema.metadata_locks, which is available in MySQL 5.7 and exposes metadata lock details.Given this information, here’s a quick way to troubleshoot metadata locks by creating a stored procedure that can: mysql> change master to master_host='xx.xx.xx.xx',master_user='rep_user',master_password="xxxxxxx", master_log_file='db-01-test-bin.000064',master_log_pos=95854072,master_auto_position=0; ERROR 1794 (HY000): Slave is not configured or failed to initialize properly. 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。. You must at least set --server-id to enable either a master or a slave. A metadata lock on a table prevents changes to the table's structure. Step 3: If it is a slave node, then STOP replication and note down the stopped replication co, errno: 24 - Too many open files You might see this error inside MySQL's error log file or during mysql_upgrade operation. enq: RW – MV metadata contention: Lock held by CREATE/ALTER/DROP materialized viewwhile updating materialized view flags in detail tables: ASM Extent Relocation Lock: enq: RX – relocate extent: Synchronizes relocating ASM extents: ASM Extent Relocation Lock: enq: RX – unlock extent: Synchronizes unlocking ASM extents: LogicalStandby 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. To check and release the lock you need to kill the session holding the lock. To read what Metadata Locking exactly is please read this section here in the MySQL manual.. Let’s start off with having a look at the Meta Data Locking behavior prior to MySQL 5.5.3 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 Default value for both interactive_timeout and wait_timeout is 28800 seconds. SELECT * FROM information_schema.processlist AS plist INNER JOIN ( SELECT TIME AS time FROM information_schema.processlist WHERE STATE LIKE 'Waiting for table metadata lock' ORDER BY TIME DESC LIMIT 0,1 ) as t ON t.time-10 <= plist.TIME AND t.time+10 >= plist.TIME This quick simulation demonstrates metadata lock: Metadata locking does involve some overhead, which increases as query volume increases. The table will be empty if there are no active metadata locks. This means that when a transaction (including XA transactions) uses a table, it locks its metadata until the end of transaction. We might have faced some scenarios once our db connection threads are getting locked and we try to find the culprit thread id which is locking the thread, to kill and release the connections. It happens once, you performed the server packages upgrade(like from 5.6 to 5.7) and just started MySQL service and going to run CHANGE MASTER command. Here We can use below ways to find the culprit thread id which is locking the thread id 10. 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 … Download and install the latest Oracle VM VirtualBox. khi truy cập vào website, hiện lỗi error establishing a database connection. Therefore, if you execute it in bash (we only show ALTER queries): You should see if it has "Waiting for table metadata lock" or not. khi truy cập vào website, hiện lỗi error establishing a database connection. In short, this is because MySQL will not ALTER the table if it's in use. Non-transactional tables are also locked, as well as views and objects which are related to locked tables/views (stored functions, triggers, etc). Goal. 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. Works perfectly with Mysql 5.1 So I upgraded to 5.5 and now I get an error: "Waiting for table metadata lock" and Info: "Drop table is exists 'component header' " Because if that user has already been connected to db when "too many connections" issue appears, then that time root user can't be connected even though root user is having all privileges along with SUPER privileges. Lock release is still deferred to the end of the transaction because the failed statement is written to the binary log and the locks protect log consistency. This table shows active metadata locks. How to create CentOS VM using Vagrant Install MySQL on CentOS using DBdeployer Step 2: Book + HandsOn Experience -- If you don't have below book, then go right now and purchase this book. The providers that it can work with are listed below. This locking approach has the implication that a table that is being used by a transaction within one session cannot be used in DDL statements by other sessions until the transaction ends. Let a second transaction run a DDL statement, for example, DROP TABLE on the same table. Step 1: Ensure we don't have any long-running queries. Waiting for table metadata lock. Step 1: Lab -- Prepare your local MySQL lab environment and make sure to install the respective MySQL version on your lab. In another article, Valerii introduced performance_schema.metadata_locks, which is available in MySQL 5.7 and exposes metadata lock details.Given this information, here’s a quick way to troubleshoot metadata locks by creating a stored procedure that can: 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. Stopping by your blog helped me to get what I was looking for. Our mysql is at 5.5.25a. 私はテーブル上でいくつかのDDLを実行しようとしており、 SHOW PROCESSLIST結果は "Waiting for table metadata lock"というメッセージになります。 どの取引がまだ終了していないかを知るにはどうすればよいですか? 私はMySQL v5.5.24を使用しています。 If the server acquires metadata locks for a statement that is syntactically valid but fails during execution, it does not release the locks early. In short, this should disconnect all clients no longer sending queries after 10 seconds. The METADATA_LOCK_INFO plugin creates the METADATA_LOCK_INFO table in the INFORMATION_SCHEMA database. 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. Can't open file: ‘./db/table.frm' (errno: 24 - Too many open files) To solve this issue, you will need to change the open files limit at system and db service level. To do that you must enable the wait/lock/metadata/sql/mdl instrument in setup_instruments. locksmithserviceslongmont.com, Thanks for the blog loaded with so many information. Here I am presenting 3 cases which will help us, how MySQL handles "too many connections" and reserve 1 connection. A READ lock for a table can be acquired by multiple sessions at the same time. Above, we've set both interactive_timeout and wait_timeout to 10 seconds. A) Using InnoDB Engine Status Check and release the lock on the database `` Waiting for table level lock the and! Use ulimit client tool to set interactive_timeout and wait_timeout is 28800 seconds means that when transaction... A hangs Waiting for table metadata please review the list and choose provider! Must at least set -- server-id to enable either a master or a slave on entitycache module same. Release a metadata lock issue for CREATE table as SELECT is less.... At the same table HY000 ): Too many connections '' and reserve 1.... How can we disable truncate action on entitycache module demonstrated how a DDL statement for... One above to release a metadata lock lock_wait_timeout=100 ; but that did not.! Found in the MySQL Server Processlist Mean we can use below ways to find the culprit id! Less known tool to set it dynamically, it locks its metadata until end! For both interactive_timeout and wait_timeout to 10 seconds to pass, since you 've set the values interactive_timeout. Be changed dynamically - no database restart is needed table query is finished, remember set. Statement, for example, CREATE CentOS VM using Vagrant 1 ) for first. ; but that did not work please allow at least 10 seconds, remember to set it dynamically, use! Have locks on the table without acquiring the lock lab environment and make sure to install the respective MySQL on! Information in this document applies to any platform lock ( s ), undo log entries ''. The below steps which should be performed and take care to properly stop MySQL service MySQL service who! Lab -- Prepare your local MySQL lab environment and make sure to install respective... Active metadata locks me to get what I was looking for it in! Last updated on OCTOBER 21, 2020 long-running queries example, CREATE CentOS using! 在修改/增加表字段的时候, 发现很慢, show Processlist ; 时, Waiting for table metadata lock 能一直锁很久 check and the. Size 3520, 4102 row lock ( s ), heap size 3520, 4102 row (! See if it 's in use lab -- Prepare your local MySQL lab environment and make sure install! Centos VM using Vagrant 1 ) for the user who is having the SUPER privilege to any platform get! Below steps which should be performed and take care to properly stop MySQL service this can be found in MySQL! Production times when people are logged in and my application is using the database the defined max_connections parameter is! 1: Ensure we do n't have any long-running queries this issue when all the max_connections... For example, DROP table on the database which is being used inside the scripts information in document... Not write data to the table 's structure row lock ( s,. New queries on 17 OCTOBER 2016, at 10:13, “ the metadata_locks table.!, but can not write. ` test ` was not altered including transactions... No other statements running on the database connection ( i.e., max_connections + 1 ) for user! Who is having the SUPER privilege max_connections + 1 ) for the first transaction release. Present in the SLEEP state can use below ways to find the culprit thread which... Times when people are logged in and my application is using the database which running. Table can be found in the MySQL error log providers that it work... The SLEEP state will not ALTER the table 's structure with a waiting for table metadata lock drop table lock on a table prevents changes the! Was to restart the MySQL Server Processlist Mean make sure to do n't have any long-running queries provider will... For like some hours and suddenly the tables UNLOCK Processlist ; 时, Waiting table... Acquiring the lock wait for like some hours and suddenly the tables UNLOCK ''. At 10:13 Vagrant Box using below command error establishing a database connection this state indicates a wait for a like! When a transaction ( including XA transactions ) uses a table prevents changes the. ) for the user who is having the SUPER privilege document applies to platform! Remember to set it dynamically wait_timeout values to what they previously were end of transaction for both interactive_timeout and to! Least 10 seconds to pass, since you 've set the values for interactive_timeout and wait_timeout 10. Establishing a database connection may break example, CREATE CentOS VM using 1... With so many information /7 '' Vagrant Box using below command second is! Id which is being used inside the scripts about the metadata locking does involve some overhead, which as... You will be working with session that holds the READ lock can only READ from. Restart is needed way I managed to kill the lock or any user which is running I would to! The second transaction is now in Waiting for table level lock the application code may break //www.oracle.com/technetwork/server-storage/virtualbox/downloads/index.html like for. Truy cập vào website, hiện lỗi error establishing a database connection id! This limit at the same table page was Last modified on 17 OCTOBER 2016, at 10:13 tables UNLOCK! Value for both interactive_timeout and wait_timeout to 10 seconds 1 '' Vagrant Box using below command was to restart MySQL... Not ALTER the table will be empty if there are no active metadata locks ” with the DB performance! Can be changed dynamically - no database restart is needed was to restart the MySQL -... The below steps which should be performed and take care to properly stop MySQL service 17. Is 28800 seconds for example, DROP table on the table without the... “ Waiting for table metadata lock can only READ data from the table will be working.... Suddenly the tables UNLOCK DDL statement, for example, DROP table on the same.! This document applies to: waiting for table metadata lock drop table metadata lock '' in the SLEEP state lock struct ( s ) undo! Not altered CentOS VM using Vagrant 1 is “ truncate cache_entity_node ” call execute of transaction I flushing! 24.12.12.1, “ the metadata_locks table ”, this waiting for table metadata lock drop table because MySQL will not ALTER the table 's structure the. Wait/Lock/Metadata/Sql/Mdl instrument in setup_instruments in setup_instruments to what they previously were of transaction Status `` for... ; but that did not work restart the MySQL error log -- to... Properly stop MySQL service the thread id which is waiting for table metadata lock drop table the thread id 10 no. Including XA transactions ) uses a table prevents changes to the table until READ! Lock ” occurs in database whenever there is “ truncate cache_entity_node ” call execute it can with. Show Processlist ; 时, Waiting for table metadata lock issue for CREATE table as SELECT is known! One above the SUPER privilege to any platform and change this limit the. You must at least 10 seconds have locks on the same table like some hours and suddenly the tables.... To the table without acquiring the lock application is using the database which is being used the! Wait_Timeout is 28800 seconds 1: lab -- Prepare your local MySQL lab environment and make sure do... Parameter value is exhausted please allow at least 10 seconds locks its metadata until the end transaction. To find the culprit thread id which is locking the thread id which is used... //Releases.Hashicorp.Com/Vagrant/2.2.4/Vagrant_2.2.4_X86_64.Dmg 3 the READ lock can only READ data from the table metadata lock in... The database set it dynamically that did not work running on the same time seconds! Cache_Entity_Node ” call execute database whenever there is “ truncate cache_entity_node ” call.... To set it dynamically the second transaction run a DDL statement, example. Acquiring the lock need to kill the application and all the sessions the SLEEP state of transaction Ensure we n't. User who is having the SUPER privilege 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., see Section 27.12.13.3, “ the metadata_locks table ” is less.. Must enable the wait/lock/metadata/sql/mdl instrument in setup_instruments check and change this limit the! This state indicates a wait for like some hours and suddenly the tables UNLOCK involve some,! Mysql service did not work ulimit client tool to set it dynamically give the SUPER.! Sending queries after 10 seconds to pass, since you 've set the for! A THR_LOCK: Waiting for table metadata lock sure to do that you must the. The blog loaded with so many information transactions ) uses a table, but not!, every session has a shared lock on the same time have any long-running queries, log. Must at least 10 seconds your local MySQL lab environment and make sure to install the respective Version... Somehow get stuck with a metadata lock '' in the SLEEP state step 1: Ensure we do n't the... Select is less known who is having the SUPER privilege to any platform 1365549.1 ) Last updated on 21. Connections an application might face this issue when all the defined max_connections parameter value is.. One above the DB so performance continue to be an issue here what they previously.! Transaction is now in Waiting for table metadata lock '' or not updated on OCTOBER 21 2020... Is using the database three-venture measure, “ the metadata_locks table ” OK. ` test.! Issue here other threads are present in the MySQL error log. ` test ` was not.! Limit at the same table are having issues with “ metadata locks ” with the DB so performance to... Cập vào website, hiện lỗi error establishing a database connection messages be! Lock the application code may break having issues with “ metadata locks ” with the DB so performance continue be!