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https://dev.mysql.com/doc/internals/en/optimizer-group-by-related-conditions.html
The optimizer contains code for shifting certain HAVING conditions to the WHERE clause; however, this code is not operative at time of writing. These are the main optimizations that take place for GROUP BY and related items (HAVING, COUNT(), MAX(), ...
https://dev.mysql.com/doc/mysql-installer/en/server-accounts-roles.html
Windows authentication permits you to test all of the security tokens each time you add or modify a token. Invalid tokens generate a descriptive error message along with a red X icon and red token text. Root Account Password Assigning a root ...
https://dev.mysql.com/doc/refman/8.4/en/innodb-standard-monitor.html
Status This section shows the timestamp, the monitor name, and the number of seconds that per-second averages are based on. The number of seconds is the elapsed time between the current time and the last time InnoDB Monitor output was printed. This ... The Lock Monitor is the same as the Standard Monitor except that it includes additional lock ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-memory-summary-tables.html
Allocating a single byte one million times is not the same as allocating one million bytes a single time; tracking both sizes and counts can expose the difference. Memory summary tables do not contain timing information because memory events are not ...Operation counts help to understand or tune the overall pressure the server is putting on the memory allocator, which has an impact on ...
https://dev.mysql.com/doc/connector-odbc/en/connector-odbc-usagenotes-apptips-microsoft-excel.html
If you have problems importing data into Microsoft Excel, particularly numeric, date, and time values, this is probably because of a bug in Excel, where the column type of the source data is used to determine the data type when that data is ...The ...
https://dev.mysql.com/doc/refman/8.4/en/mysql-commands.html
mysql sends each SQL statement that you issue to the server to be executed. If there is a concern that optimizer-hint comments may be stored in object definitions so that dump files when reloaded with mysql would result in execution of such ...
https://dev.mysql.com/doc/refman/8.4/en/check-table.html
A table is reported as needing a rebuild if it contains old temporal columns in pre-5.6.4 format (TIME, DATETIME, and TIMESTAMP columns without support for fractional seconds precision). If CHECK TABLE encounters errors in InnoDB tables or indexes, ...option: { FOR UPGRADE | QUICK | FAST | MEDIUM | EXTENDED | CHANGED } CHECK TABLE checks a table or tables for ...CHECK ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-events-stages-current-table.html
For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 29.4.1, “Performance Schema Event Timing”. For example, the events_stages_history and events_stages_history_long tables are collections of ...The table stores one row per thread showing the current status of the thread's most recent monitored stage event, so there is no system variable for configuring the table ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-events-transactions-current-table.html
For discussion of picoseconds as the unit for event times and factors that affect time values, see Section 29.4.1, “Performance Schema Event Timing”. For example, the events_transactions_history and events_transactions_history_long tables are ...
https://dev.mysql.com/doc/internals/en/flush-tables.html
Every time a thread releases a table, it checks if the refresh version of the table (updated at open) is the same as the current refresh_version. The idea of FLUSH TABLES is to force all tables to be closed. This is mainly to ensure that if someone ...