![]() If it is found to exist, the statement will be terminated.Ģ. When executing SELECT query, in the ORDER BY or GROUP BY loop, the kill tag bit will be checked after reading some row record blocks each time. It usually takes a while to actually shut down a thread, because kill tag bits are checked only under certain circumstances:ġ. KILL QUERY only stops the current committed operation of the thread, and everything else remains unchanged.Īfter committing a KILL operation, a special KILL tag bit is set on that thread. KILL CONNECTION as before, stop the rollback transaction, close the thread CONNECTION, and release related resources Starting with 5.0, KILL supports specifying two options for CONNECTION | QUERY: Refresh all table cache and close all open tables Įach storage engine is responsible for the relevant shutdown operation, for example, MyISAM will refresh all operations waiting to be written InnoDB will flush the Buffer pool to disk (starting with MySQL 5.0.5, if innodb_fast_shutdown is not set to 2), record the current LSN into the table space, and then close all internal threads. When Slave SQL thread is forced to KILL when performing operation on non-transacted table, it may cause inconsistency of Master and Slave data ĥ, MySQL Server process shut down all threads, shut down all storage engines Starting at 5.0.81, you wait for all operations to end unless the user initiates a KILL operation. In MySQl 5.0.80 and earlier, if the SQL thread was executing a transaction in the middle, the transaction would be rolled back. On Slave server, SQL thread is allowed to stop the current SQL operation directly (to avoid replication problems) and then close the thread If the two threads are active at the moment, the killed mark will also be added and then closed. If it’s Slave in Master/Slave replication, the IO and SQL threads will be closed in turn. If it’s the Master in the Master/Slave replication scenario, the process for the replicated thread is the same as for the normal thread If the non-transactional table is modified in the transaction, the modified data cannot be rolled back, and only part of the changes may be completed. If there is an active transaction, the transaction will be rolled back. There are also currently transactions, SQL active connections, which are identified as killed and periodically checked for status so that they can be closed the next time they are checked (Refer to KILL syntax) ![]() Idle connections will be terminated immediately Gradually close the current connection and transaction MySQL Server will no longer respond to new connection requestsĬlose TCP/IP network monitoring, close Unix Socket and other channelsĤ. When a separate close thread cannot be created (for example, out of memory), MySQL Server issues an alert similar to the following:Įrror: Can’t create thread to kill serverģ. If the SIGTERM signal is received directly to shut down, a thread dedicated to processing the signal will do so, or a separate thread will be created to do so If it is a client-initiated shutdown, a dedicated shutdown thread is created Launch shutdown and issue SIGTERM signalĢ. Each storage engine is responsible for the relevant shutdown operation, for example, MyISAM will refresh all operations waiting to be written InnoDB will flush the Buffer pool to disk (from MySQL 5.0.5)ġ.
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