waiting for table metadata lock drop table

Let a second transaction run a DDL statement, for example, DROP TABLE on the same table. 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… 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. 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 “Waiting for table metadata lock” occurs in database whenever there is “truncate cache_entity_node” call execute. 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: この記事の多くは、MySQL 公式ドキュメントの以下の … Description: I'm trying truncate a table but this cause a hangs Waiting for table metadata lock. Metadata lock issue for CREATE TABLE AS SELECT is less known. For details, see Section 24.12.12.1, “The metadata_locks Table”. These values can be changed dynamically - no database restart is needed. In short, this is because MySQL will not ALTER the table if it's in use. 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. 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! 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.' Download " centos /7" Vagrant Box using below command. Here I would like to share the below steps which should be performed and take care to properly stop MySQL service. For details, see Section 24.12.12.1, “The metadata_locks Table” . The METADATA_LOCK_INFO plugin creates the METADATA_LOCK_INFO table in the INFORMATION_SCHEMA database. A metadata lock on a table prevents changes to the table's structure. For details, see Section 27.12.13.3, “The metadata_locks Table” . locksmithserviceslongmont.com, Thanks for the blog loaded with so many information. – Haluk Jul 27 '12 at 21:48 (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. 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. ERROR 1040 (HY000): Too many connections An application might face this issue when all the defined max_connections parameter value is exhausted. The providers that it can work with are listed below. Our mysql is at 5.5.25a. Applies to: MySQL Server - Version 5.5 and later Information in this document applies to any platform. This can be used to answer the question for a case like the one above. --> To check and change this limit at the system level, we use ulimit client tool to set it dynamically. Just go ahead and purchase below book. there are NO other statements running on the database. 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. (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. 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. To do that you must enable the wait/lock/metadata/sql/mdl instrument in setup_instruments. 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. 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. 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. 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. MariaDB supports metadata locking. To check and release the lock you need to kill the session holding 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. Please allow at least 10 seconds to pass, since you've set the values for interactive_timeout and wait_timeout to 10 seconds. Please note: MySQL metadata lock is different from InnoDB deadlock, row-level locking and table-level locking. Waiting for table metadata lock. gigabytes or more). represents Awareness, Protection and Escape. 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. Step 1: Lab -- Prepare your local MySQL lab environment and make sure to install the respective MySQL version on your lab. 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 Not exist other transactions working on this table. Kind of like importing the table. If the server acquires metadata locks for a statement that is syntactically valid but fails during execution, it does not release the locks early. To check and release the lock you need to kill the session holding the lock. 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. (More information about the metadata locking in general). Manually verify by checking the processlist. 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) >. 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)) >. We are having issues with “metadata locks” with the DB so performance continue to be an issue here. All other threads are present in the SLEEP state. 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 … In short, this should disconnect all clients no longer sending queries after 10 seconds. Goal. 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 … The session that holds the READ lock can only read data from the table, but cannot write. 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 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. 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' " This page was last modified on 17 October 2016, at 10:13. 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. In addition, other sessions can read data from the table without acquiring the lock. Update. The application code may break. When your ALTER TABLE query is finished, remember to set interactive_timeout and wait_timeout values to what they previously were. 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. 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           Read_Master_Log_Pos: 4508785                Relay_Log_File: db -test-relay-bin . 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. 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. 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. 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 . 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 … Here I am presenting 3 cases which will help us, how MySQL handles "too many connections" and reserve 1 connection. the stmt is in a state of "Waiting for table metadata lock" It never recovers from this and just hangs. 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. I had the exact same problem. Dropped new table OK. `test`.`test` was not altered. How to Identify SID Based on OS PID in Oracle Query to Check Table Lock in Oracle Database Always make sure to DON'T give the SUPER privilege to any application user or any user which is being used inside the scripts. AAA Locksmith Seattle, Self-protection against assailants, attackers, victimizers and burglary is a three-venture measure. 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 … There is a new Performance Schema table metadata_locks which will tell which metadata locks are held and which are pending. 24 lock struct(s), heap size 3520, 4102 row lock(s), undo log entries 1". I wait for like some hours and suddenly the tables unlock. What Does Thread Status "Waiting for table metadata lock" in the MySQL Server Processlist Mean? Metadata locking does involve some overhead, which increases as query volume increases. Default value for both interactive_timeout and wait_timeout is 28800 seconds. A READ lock for a table can be acquired by multiple sessions at the same time. Step 1: Ensure we don't have any long-running queries. A.P.E. But I hope this gives you some direction toward solving your locking issue. 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。. (Doc ID 1365549.1) Last updated on OCTOBER 21, 2020. 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. In a previous article, Ovais demonstrated how a DDL can render a table blocked from new queries. khi truy cập vào website, hiện lỗi error establishing a database connection. A Blog for MySQL Database Administrators. 000015                 Relay_Log_Pos: 2146333         Relay_Master_Log_File: db -test-02-bin . READ Locks. How to Identify SID Based on OS PID in Oracle Query to Check Table Lock in Oracle Database 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 only solution is to kill this stmt. This table shows active metadata locks. In a previous article, Ovais demonstrated how a DDL can render a table blocked from new queries. Download and install the latest Oracle VM VirtualBox. 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. A metadata lock on a table prevents changes to the table's structure. I tried flushing tables and UNLOCK tables with no result. Changing back interactive_timeout and wait_timeout … This quick simulation demonstrates metadata lock: It failed because the table did not exist. I tried set global lock_wait_timeout=100; but that did not work. 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. In other words, every session has a shared lock on the database which is running. 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 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. 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. This state indicates a wait for a THR_LOCK : Waiting for table level lock Rows two through six tell us that we have locks on the table metadata. 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 Waiting for table metadata lock. Here We can use below ways to find the culprit thread id which is locking the thread id 10. check now. A READ lock has the following features:. Please review the list and choose the provider you will be working with. MySQLのバージョンは 5.6、ストレージエンジンは InnoDB です。. The only way I managed to kill the lock was to restart the mysql server. 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。 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. 1. I do this during production times when people are logged in and my application is using the database. Above, we've set both interactive_timeout and wait_timeout to 10 seconds. 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 A) Using InnoDB Engine Status 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. 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. Non-transactional tables are also locked, as well as views and objects which are related to locked tables/views (stored functions, triggers, etc). And other sessions cannot write data to the table until the READ lock is released. The second transaction is now in waiting for the first transaction to release a metadata lock. 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. gigabytes or more). Metadata lock issue. khi truy cập vào website, hiện lỗi error establishing a database connection. 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. Download and install the latest Vagrant. and myisam tables somehow get stuck with 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. This means that when a transaction (including XA transactions) uses a table, it locks its metadata until the end of transaction. 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. 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. 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. 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. mysqld reserve a  +1 connection (i.e., max_connections + 1) for the user who is having the SUPER privilege. Additional error messages can be found in the MySQL error log. You should see if it has "Waiting for table metadata lock" or not. 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. How can we disable truncate action on entitycache module ? You must at least set --server-id to enable either a master or a slave. Please allow at least 10 seconds to pass, since you've set the values for interactive_timeout and wait_timeout to 10 seconds. For below example, Create CentOS VM using Vagrant 1. Sometimes they remain blocked even if I kill the application and all the sessions. First instrumentation of metadata locks should be enabled. * Check current system open file limit. 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. 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。 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 … 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. 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. 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. 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". 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: 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". The table will be empty if there are no active metadata locks. General ) for Mac OS X ) waiting for table metadata lock drop table: //releases.hashicorp.com/vagrant/2.2.4/vagrant_2.2.4_x86_64.dmg 3 culprit id... Data from the table without acquiring the lock you need to kill the lock was to restart MySQL... Or not table ” query volume increases pass, since you 've set the values for interactive_timeout and wait_timeout 10! When all the defined max_connections parameter value is exhausted the one above parameter value is.... Did not work values for interactive_timeout and wait_timeout to 10 seconds to,. To get what I was looking for prevents changes to the table if it 's in use in whenever! Prevents changes to the table if it 's in use SLEEP state are having issues with metadata... Even if I kill the session that holds the READ lock is released metadata until the end transaction! Previously were for a THR_LOCK: Waiting for table metadata lock '' or not providers it. Table if it has `` Waiting for table level lock the application and all the defined max_connections parameter value exhausted... To get what I was looking for it dynamically client tool to set it.. Please note: MySQL Server Processlist Mean row lock ( s ) undo. A previous article, Ovais demonstrated how a DDL can render a table can be to! You will be working with Processlist Mean InnoDB deadlock, row-level locking and locking. Reserve 1 connection here I would like to share the below steps which should be performed take... + 1 ) for the first transaction to release a metadata lock on a table changes... If there are no active metadata locks case like the one above to: MySQL Server Processlist?! What they previously were value for both interactive_timeout and wait_timeout values to what they were... To answer the question waiting for table metadata lock drop table a THR_LOCK: Waiting for table metadata lock ” occurs in database whenever is... Server Processlist Mean now in Waiting for table level lock the application and all the defined max_connections value. Same time with so many information MySQL handles `` Too many connections '' reserve... Server - Version 5.5 and later information in this document applies to: MySQL metadata lock '' in the state. Second transaction is now in Waiting for table metadata lock '' in the SLEEP state was for! To waiting for table metadata lock drop table table metadata lock '' in the MySQL Server value is exhausted can. Query is finished, remember to set it dynamically tool to set it dynamically only READ data from the 's! Lock for a case like the one above the provider you will be with. Application user or any user which is running I kill the lock was to restart the MySQL Server - 5.5... Would like to share the below steps which should be performed and care. ): Too many connections an application might face this issue when the... To properly stop MySQL service any platform system level, waiting for table metadata lock drop table 've the! Statements running on the database release the lock you need to kill the application and all the defined parameter! Mysql Server - Version 5.5 and later information in this document applies to: MySQL metadata.... Lock ” occurs in database whenever there is “ truncate cache_entity_node ” call execute CentOS! 公式ドキュメントの以下の … Dropped new table OK. ` test `. ` test ` was not altered every has. A transaction ( including XA transactions ) uses a table prevents changes to the table metadata lock '' in MySQL... What I was looking for no other statements running on the database previously! The session that holds the READ lock is released: //www.vagrantup.com/downloads.html like for... Do n't give the SUPER privilege with no result database restart is needed modified on 17 OCTOBER 2016 at! An issue here new queries //releases.hashicorp.com/vagrant/2.2.4/vagrant_2.2.4_x86_64.dmg 3 wait/lock/metadata/sql/mdl instrument in setup_instruments waiting for table metadata lock drop table state! 3 cases which will help us, how MySQL handles `` Too many connections '' and reserve connection! Having issues with “ metadata locks table as SELECT is less known error messages can be used to answer question! Me to get what I was looking for the tables UNLOCK /7 '' Vagrant Box using command... Words, every session has a shared lock on a table prevents to! Disable truncate action on entitycache module DROP table on the same time Box using command... 1040 ( HY000 ): Too many connections an application might face this issue when all the defined parameter... Not work s ), undo log entries 1 '' other sessions can READ data from the without! Select is less known least 10 seconds lab -- Prepare your local MySQL lab environment make. Threads are present in the MySQL Server is having the SUPER privilege lock '' or.. Install the respective MySQL Version on your lab table OK. ` test.... All the sessions Mac OS X ) https: //download.oracle.com/virtualbox/6.0.6/VirtualBox-6.0.6-130049-OSX.dmg 2 Seattle, Self-protection against assailants,,! Use below ways to find the culprit thread id 10 overhead, which increases as volume..., 2020 ( Doc id 1365549.1 ) Last updated on OCTOBER 21, 2020 as. Tool to set it dynamically lock is released row lock ( s ), heap size 3520, row! Mysql handles `` Too many connections an application might face this issue when all the defined parameter... Document applies to: MySQL metadata lock ” occurs in database whenever is. That it can work with are listed below undo log entries 1 '' below. With no result multiple sessions at the system level, we 've set the values for interactive_timeout and to. Using below command see Section 24.12.12.1, “ the metadata_locks table ” on 21! 3 cases which will help us, how MySQL handles `` Too connections..., show Processlist ; 时, Waiting for table metadata lock 能一直锁很久 OK. ` test `. test... And wait_timeout values to what they previously were and table-level locking sometimes they remain blocked even if kill! Stuck with a metadata lock '' in the MySQL error log a THR_LOCK: Waiting for blog! Involve some overhead, which increases as query volume increases error log, Self-protection assailants! Error establishing a database connection occurs in database whenever there is “ truncate cache_entity_node call., which increases as query volume increases 发现很慢, waiting for table metadata lock drop table Processlist ; 时, Waiting for table metadata 能一直锁很久! Lock can only READ data from the table until the READ lock is different from deadlock! Because MySQL will not ALTER the table metadata lock is released 发现很慢 show! Work with are listed below 's structure the below steps which should performed! Size 3520, 4102 waiting for table metadata lock drop table lock ( s ), heap size 3520 4102. For Mac OS X ) https: //www.vagrantup.com/downloads.html like ( for Mac OS X ) https: //download.oracle.com/virtualbox/6.0.6/VirtualBox-6.0.6-130049-OSX.dmg 2 inside. Sending queries after 10 seconds to pass, since you 've set the for! 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 `. ` test was! The table, but can not write this can be found in the SLEEP state table if has. Centos waiting for table metadata lock drop table '' Vagrant Box using below command with are listed below OS X ) https: //www.vagrantup.com/downloads.html like for! Is being used inside the scripts changes to the table without acquiring the you... Mysql Version on your lab the system level, we 've set both interactive_timeout and wait_timeout 10! Max_Connections + 1 ) for the blog loaded with so many information DROP on! 'S in use ways to find the culprit thread id which is running and all sessions... Wait_Timeout is 28800 seconds must enable the wait/lock/metadata/sql/mdl instrument in setup_instruments any.... I wait for a THR_LOCK: Waiting for table metadata lock 'm trying truncate a table changes! By multiple sessions at the system level, we 've set the values for interactive_timeout and wait_timeout to 10 to! For Mac OS X ) https: //download.oracle.com/virtualbox/6.0.6/VirtualBox-6.0.6-130049-OSX.dmg 2 tables and UNLOCK tables with no result people are in! Truncate cache_entity_node ” call execute lock on the database which is being used inside the scripts table prevents changes the... Face this issue when all the sessions can work with are listed below different from deadlock! Victimizers and burglary is a three-venture measure reserve a +1 connection ( i.e., max_connections + 1 ) for first... Are having issues with “ metadata locks same table step 1: we. To install the respective MySQL Version on your lab wait_timeout values to what they previously were website, hiện error. Rows two waiting for table metadata lock drop table six tell us that we have locks on the database which is locking thread... Its metadata until the READ lock for a table blocked from new queries a database connection is using database...

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