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https://dev.mysql.com/doc/refman/8.0/en/server-status-variables.html
Slow_queries The number of queries that have taken more than long_query_time seconds. If this value is high, it is a good indication that your tables are properly indexed for your queries. This value is high if you are doing a lot of queries that ...
https://dev.mysql.com/doc/refman/8.0/en/using-log-files.html
You can find the queries that take a long time to execute by starting mysqld with the slow query log enabled. If this works, you should also test all complicated queries that did not complete. If this happens, you should check all your tables with ... Note that before starting mysqld with the general query log enabled, you should check all your tables with ...
https://dev.mysql.com/doc/refman/8.0/en/general-thread-states.html
logging slow query The thread is writing a statement to the slow-query log. The following list describes thread State values that are associated with general query processing and not more specialized activities such as replication. Many of these ...
https://dev.mysql.com/doc/refman/8.0/en/upgrading-from-previous-series.html
Upgrade from MySQL 5.7 to MySQL 8.0 requires a slow shutdown which ensures that undo tablespaces in the MySQL 5.7 instance are empty, permitting them to be removed safely. Upgrade within the MySQL 8.0 release series may not always require a slow ...
https://dev.mysql.com/doc/refman/8.0/en/innodb-change-buffer.html
During this time, disk I/O is increased, which can cause a significant slowdown for disk-bound queries. Periodically, the purge operation that runs when the system is mostly idle, or during a slow shutdown, writes the updated index pages to disk.
https://dev.mysql.com/doc/refman/8.0/en/programs-overview.html
mysqldumpslow A utility to read and summarize the contents of a slow query log. Oracle Corporation also provides the MySQL Workbench GUI tool, which is used to administer MySQL servers and databases, to create, execute, and evaluate queries, and to ...Later sections provide a more detailed description of each one, with the exception of NDB Cluster ...
https://dev.mysql.com/doc/refman/8.0/en/optimizing-innodb-diskio.html
If you follow best practices for database design and tuning techniques for SQL operations, but your database is still slow due to heavy disk I/O activity, consider these disk I/O optimizations. Increase buffer pool size When table data is cached in ...If the Unix top tool or the Windows Task Manager shows that the CPU usage percentage with your workload is less than 70%, your workload is probably ...
https://dev.mysql.com/doc/refman/8.0/en/performance-schema-timing.html
Processor cycle rate might change, such as when a laptop goes into power-saving mode or when a CPU slows down to reduce heat generation. Some processor details related to out-of-order execution or multiprocessor synchronization might cause the ...
https://dev.mysql.com/doc/refman/8.0/en/group-replication-flow-control.html
Depending on why the member is lagging behind, other members in the group may have to save more or less of the replication context to be able to fulfil potential data transfer requests from the slow member. The replication protocol provides a ...
https://dev.mysql.com/doc/refman/8.0/en/group-replication-frequently-asked-questions.html
Otherwise, if the server is so slow that it triggers the flow control, then the entire group slows down as well. What is the maximum number of MySQL servers in a group? A group can consist of maximum 9 servers. Attempting to add another server to a ...