Flush hosts mysql windows

The FLUSH statement has several variant forms that clear or reload various internal caches, flush tables, or acquire locks. Each FLUSH operation requires the privileges indicated in its description.

It is not possible to issue FLUSH statements within stored functions or triggers. However, you may use FLUSH in stored procedures, so long as these are not called from stored functions or triggers. See Section 25.8, “Restrictions on Stored Programs”.

By default, the server writes FLUSH statements to the binary log so that they replicate to replicas. To suppress logging, specify the optional NO_WRITE_TO_BINLOG keyword or its alias LOCAL .

FLUSH LOGS , FLUSH BINARY LOGS , FLUSH TABLES WITH READ LOCK (with or without a table list), and FLUSH TABLES tbl_name . FOR EXPORT are not written to the binary log in any case because they would cause problems if replicated to a replica.

The mysqladmin utility provides a command-line interface to some flush operations, using commands such as flush-hosts , flush-logs , flush-privileges , flush-status , and flush-tables . See Section 4.5.2, “mysqladmin — A MySQL Server Administration Program”.

Sending a SIGHUP or SIGUSR1 signal to the server causes several flush operations to occur that are similar to various forms of the FLUSH statement. Signals can be sent by the root system account or the system account that owns the server process. This enables the flush operations to be performed without having to connect to the server, which requires a MySQL account that has privileges sufficient for those operations. See Section 4.10, “Unix Signal Handling in MySQL”.

The RESET statement is similar to FLUSH . See Section 13.7.8.6, “RESET Statement”, for information about using RESET with replication.

The following list describes the permitted FLUSH statement flush_option values. For descriptions of the permitted tables_option values, see FLUSH TABLES Syntax.

Closes and reopens any binary log file to which the server is writing. If binary logging is enabled, the sequence number of the binary log file is incremented by one relative to the previous file.

This operation requires the RELOAD privilege.

Closes and reopens any flushable logs for installed storage engines. This causes InnoDB to flush its logs to disk.

This operation requires the RELOAD privilege.

Closes and reopens any error log file to which the server is writing.

This operation requires the RELOAD privilege.

Closes and reopens any general query log file to which the server is writing.

This operation requires the RELOAD privilege.

This operation has no effect on tables used for the general query log (see Section 5.4.1, “Selecting General Query Log and Slow Query Log Output Destinations”).

Empties the host cache and the Performance Schema host_cache table that exposes the cache contents, and unblocks any blocked hosts.

This operation requires the RELOAD privilege.

For information about why host cache flushing might be advisable or desirable, see Section 5.1.12.3, “DNS Lookups and the Host Cache”.

FLUSH HOSTS is deprecated as of MySQL 8.0.23; expect it to be removed in a future MySQL release. Instead, truncate the Performance Schema host_cache table:

The TRUNCATE TABLE operation requires the DROP privilege for the table rather than the RELOAD privilege.

Closes and reopens any log file to which the server is writing.

This operation requires the RELOAD privilege.

The effect of this operation is equivalent to the combined effects of these operations:

Re-reads the cost model tables so that the optimizer starts using the current cost estimates stored in them.

This operation requires the FLUSH_OPTIMIZER_COSTS or RELOAD privilege.

The server writes a warning to the error log for any unrecognized cost model table entries. For information about these tables, see Section 8.9.5, “The Optimizer Cost Model”. This operation affects only sessions that begin subsequent to the flush. Existing sessions continue to use the cost estimates that were current when they began.

Re-reads the privileges from the grant tables in the mysql system schema. As part of this operation, the server reads the global_grants table containing dynamic privilege assignments and registers any unregistered privileges found there.

This operation requires the RELOAD privilege.

If the —skip-grant-tables option was specified at server startup to disable the MySQL privilege system, FLUSH PRIVILEGES provides a way to enable the privilege system at runtime.

Resets failed-login tracking (or enables it if the server was started with —skip-grant-tables ) and unlocks any temporarily locked accounts. See Section 6.2.15, “Password Management”.

Frees memory cached by the server as a result of GRANT , CREATE USER , CREATE SERVER , and INSTALL PLUGIN statements. This memory is not released by the corresponding REVOKE , DROP USER , DROP SERVER , and UNINSTALL PLUGIN statements, so for a server that executes many instances of the statements that cause caching, there is an increase in cached memory use unless it is freed with FLUSH PRIVILEGES .

Clears the in-memory cache used by the caching_sha2_password authentication plugin. See Cache Operation for SHA-2 Pluggable Authentication.

Closes and reopens any relay log file to which the server is writing. If relay logging is enabled, the sequence number of the relay log file is incremented by one relative to the previous file.

This operation requires the RELOAD privilege.

The FOR CHANNEL channel clause enables you to name which replication channel the operation applies to. Execute FLUSH RELAY LOGS FOR CHANNEL channel to flush the relay log for a specific replication channel. If no channel is named and no extra replication channels exist, the operation applies to the default channel. If no channel is named and multiple replication channels exist, the operation applies to all replication channels. For more information, see Section 17.2.2, “Replication Channels”.

Closes and reopens any slow query log file to which the server is writing.

This operation requires the RELOAD privilege.

This operation has no effect on tables used for the slow query log (see Section 5.4.1, “Selecting General Query Log and Slow Query Log Output Destinations”).

Flushes status indicators.

This operation requires the FLUSH_STATUS or RELOAD privilege.

This operation adds the session status from all active sessions to the global status variables, resets the status of all active sessions, and resets account, host, and user status values aggregated from disconnected sessions. See Section 27.12.15, “Performance Schema Status Variable Tables”. This information may be of use when debugging a query. See Section 1.6, “How to Report Bugs or Problems”.

Resets all per-hour user resource indicators to zero.

This operation requires the FLUSH_USER_RESOURCES or RELOAD privilege.

Resetting resource indicators enables clients that have reached their hourly connection, query, or update limits to resume activity immediately. FLUSH USER_RESOURCES does not apply to the limit on maximum simultaneous connections that is controlled by the max_user_connections system variable. See Section 6.2.20, “Setting Account Resource Limits”.

FLUSH TABLES Syntax

FLUSH TABLES flushes tables, and, depending on the variant used, acquires locks. Any TABLES variant used in a FLUSH statement must be the only option used. FLUSH TABLE is a synonym for FLUSH TABLES .

The descriptions here that indicate tables are flushed by closing them apply differently for InnoDB , which flushes table contents to disk but leaves them open. This still permits table files to be copied while the tables are open, as long as other activity does not modify them.

Closes all open tables, forces all tables in use to be closed, and flushes the prepared statement cache.

This operation requires the FLUSH_TABLES or RELOAD privilege.

FLUSH TABLES is not permitted when there is an active LOCK TABLES . READ . To flush and lock tables, use FLUSH TABLES tbl_name . WITH READ LOCK instead.

With a list of one or more comma-separated table names, this operation is like FLUSH TABLES with no names except that the server flushes only the named tables. If a named table does not exist, no error occurs.

This operation requires the FLUSH_TABLES or RELOAD privilege.

Closes all open tables and locks all tables for all databases with a global read lock.

This operation requires the FLUSH_TABLES or RELOAD privilege.

This operation is a very convenient way to get backups if you have a file system such as Veritas or ZFS that can take snapshots in time. Use UNLOCK TABLES to release the lock.

FLUSH TABLES WITH READ LOCK acquires a global read lock rather than table locks, so it is not subject to the same behavior as LOCK TABLES and UNLOCK TABLES with respect to table locking and implicit commits:

UNLOCK TABLES implicitly commits any active transaction only if any tables currently have been locked with LOCK TABLES . The commit does not occur for UNLOCK TABLES following FLUSH TABLES WITH READ LOCK because the latter statement does not acquire table locks.

Beginning a transaction causes table locks acquired with LOCK TABLES to be released, as though you had executed UNLOCK TABLES . Beginning a transaction does not release a global read lock acquired with FLUSH TABLES WITH READ LOCK .

Flushes and acquires read locks for the named tables.

This operation requires the FLUSH_TABLES or RELOAD privilege. Because it acquires table locks, it also requires the LOCK TABLES privilege for each table.

The operation first acquires exclusive metadata locks for the tables, so it waits for transactions that have those tables open to complete. Then the operation flushes the tables from the table cache, reopens the tables, acquires table locks (like LOCK TABLES . READ ), and downgrades the metadata locks from exclusive to shared. After the operation acquires locks and downgrades the metadata locks, other sessions can read but not modify the tables.

This operation applies only to existing base (non- TEMPORARY) tables. If a name refers to a base table, that table is used. If it refers to a TEMPORARY table, it is ignored. If a name applies to a view, an ER_WRONG_OBJECT error occurs. Otherwise, an ER_NO_SUCH_TABLE error occurs.

Use UNLOCK TABLES to release the locks, LOCK TABLES to release the locks and acquire other locks, or START TRANSACTION to release the locks and begin a new transaction.

This FLUSH TABLES variant enables tables to be flushed and locked in a single operation. It provides a workaround for the restriction that FLUSH TABLES is not permitted when there is an active LOCK TABLES . READ .

This operation does not perform an implicit UNLOCK TABLES , so an error results if you perform the operation while there is any active LOCK TABLES or use it a second time without first releasing the locks acquired.

If a flushed table was opened with HANDLER , the handler is implicitly flushed and loses its position.

This FLUSH TABLES variant applies to InnoDB tables. It ensures that changes to the named tables have been flushed to disk so that binary table copies can be made while the server is running.

This operation requires the FLUSH_TABLES or RELOAD privilege. Because it acquires locks on tables in preparation for exporting them, it also requires the LOCK TABLES and SELECT privileges for each table.

The operation works like this:

It acquires shared metadata locks for the named tables. The operation blocks as long as other sessions have active transactions that have modified those tables or hold table locks for them. When the locks have been acquired, the operation blocks transactions that attempt to update the tables, while permitting read-only operations to continue.

It checks whether all storage engines for the tables support FOR EXPORT . If any do not, an ER_ILLEGAL_HA error occurs and the operation fails.

The operation notifies the storage engine for each table to make the table ready for export. The storage engine must ensure that any pending changes are written to disk.

The operation puts the session in lock-tables mode so that the metadata locks acquired earlier are not released when the FOR EXPORT operation completes.

This operation applies only to existing base (non- TEMPORARY ) tables. If a name refers to a base table, that table is used. If it refers to a TEMPORARY table, it is ignored. If a name applies to a view, an ER_WRONG_OBJECT error occurs. Otherwise, an ER_NO_SUCH_TABLE error occurs.

InnoDB supports FOR EXPORT for tables that have their own .ibd file file (that is, tables created with the innodb_file_per_table setting enabled). InnoDB ensures when notified by the FOR EXPORT operation that any changes have been flushed to disk. This permits a binary copy of table contents to be made while the FOR EXPORT operation is in effect because the .ibd file is transaction consistent and can be copied while the server is running. FOR EXPORT does not apply to InnoDB system tablespace files, or to InnoDB tables that have FULLTEXT indexes.

FLUSH TABLES . FOR EXPORT is supported for partitioned InnoDB tables.

When notified by FOR EXPORT , InnoDB writes to disk certain kinds of data that is normally held in memory or in separate disk buffers outside the tablespace files. For each table, InnoDB also produces a file named table_name .cfg in the same database directory as the table. The .cfg file contains metadata needed to reimport the tablespace files later, into the same or different server.

When the FOR EXPORT operation completes, InnoDB has flushed all dirty pages to the table data files. Any change buffer entries are merged prior to flushing. At this point, the tables are locked and quiescent: The tables are in a transactionally consistent state on disk and you can copy the .ibd tablespace files along with the corresponding .cfg files to get a consistent snapshot of those tables.

For the procedure to reimport the copied table data into a MySQL instance, see Section 15.6.1.3, “Importing InnoDB Tables”.

After you are done with the tables, use UNLOCK TABLES to release the locks, LOCK TABLES to release the locks and acquire other locks, or START TRANSACTION to release the locks and begin a new transaction.

While any of these statements is in effect within the session, attempts to use FLUSH TABLES . FOR EXPORT produce an error:

While FLUSH TABLES . FOR EXPORT is in effect within the session, attempts to use any of these statements produce an error:

Linux и Windows: помощь админам и пользователям

Администрируем и настраиваем Windows, Linux.

15 практических примеров использования команд Mysqladmin для администрирования MySQL сервера

В 15 примерах использования команд mysqladmin ниже, используется пароль root Mysql tmppassword. Поменяйте его на ваш пароль

1. Как изменить пароль root на Mysql?

2. Как проверить работает ли MySQL сервер?

3. Как посмотреть какая версия MySQL используетсяI am running?

[cut]Эта команда так же отображает текущий статус сервера.

4. Как посмотреть статус MySQL сервера?

Команда status отображает следующую информациюcommand displays the following information:

• Uptime: Время безотказной работы в секундах
• Threads: Общее количество клиентов, подключенных к серверу.
• Questions: Общее количество запросов к серверу с момента запуска.
• Slow queries: Общее количество запросов, чьё время выполнения было больше чем значение переменной long_query_time.
• Opens: Total number of tables opened by the server.
• Flush tables: How many times the tables were flushed.
• Open tables: Total number of open tables in the database.

5. Как просмотреть статус переменных MySQL и их текущее значение?

6. Как отобразить все системные переменные MySQL сервера и их значения?

7. Как отобразить все запущенные процессы/запросы в базе mysql?

Вы можете использовать эту команду для эффективного дебага любых проблем с производительностью и определять процесс, который вызывает проблемы, запустив команду на автообновление каждую секунду.

8. Как создать базу MySQL?

Замечание: Для отображения все таблиц в базе данных, общего количества колонок, строк, индексов и прочее. используйте команду mysqlshow.

9. Как удалить существующую базу MySQL?

10. Как перегрузить все привилегии и права на таблицы?

Команда Refresh сбросит все таблица и закроет/откроет лог-файлы.

11. Как образом выполнить безопасную остановку MySQL сервера?

Вы можете использовать команду “/etc/rc.d/init.d/mysqld stop” для остановки сервера. Для запуска выполните “/etc/rc.d/init.d/mysql start”

12. Список всех mysqladmin flush комманд.

• flush-hosts: Сбросить всю информацию в кэше хостов.
• flush-privileges: Перезагрузить права.
• flush-status: Очистить статус переменных.
• flush-threads: Flush the thread cache.

13. Как убить подвешенный клиентский процесс в MySQL ?

Сперва определите подвешенный процесс используя команду processlist.

Затем используйте команду kill и нужный process_id. Для завершения нескольких процессов разделите process id запятыми.

14. Как запустить или остановить репликацию MySQL на slave-сервер?

15. Как скомбинировать несколько команд mysqladmin вместе?

В примере ниже скомбинированы команды process-list, status и version для полного вывода статуса сервера.

Вы можете также использовать краткую форму записи:

Используйте опцию -h для подключения к удаленному MySQL серверу и выполнения команды.

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