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https://dev.mysql.com/doc/refman/8.4/en/performance-schema-setup-objects-table.html
Rows can be inserted into or deleted from setup_objects by users with the INSERT or DELETE privilege on the table. For existing rows, only the ENABLED and TIMED columns can be modified, by users with the UPDATE privilege on the table. The ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-characteristics.html
The name of the performance_schema database is lowercase, as are the names of tables within it. Many tables in the performance_schema database are read only and cannot be modified: mysql> TRUNCATE TABLE performance_schema.setup_instruments; ERROR ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-table-wait-summary-tables.html
In this way, aggregations at higher levels are available directly without the need for user-defined views that sum lower-level columns. In this way, aggregations at higher levels are available directly without the need for user-defined views that ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-timing.html
Cycle counters also have disadvantages: End users expect to see timings in wall-clock units, such as fractions of a second. For example, on Pentiums, the instruction is RDTSC (an assembly-language rather than a C instruction) and it is theoretically ... Events are collected by means of instrumentation added to the server source ...
https://dev.mysql.com/doc/refman/8.4/en/performance-schema-tp-connections-table.html
CONNECT_HANDLER_INDEX The index of the connection handler thread in the group which processed the connection request; a higher number means the connection load has triggered the creation of additional connection handler threads. TYPE The connection ... The tp_connections table contains one row per connection managed by the Thread Pool ...
https://dev.mysql.com/doc/refman/8.4/en/preventing-use-of-optimizer-trace.html
If, for some reason, you wish to prevent users from seeing traces of their queries, start the server with the options shown here: --maximum-optimizer-trace-max-mem-size=0 --optimizer-trace-max-mem-size=0 This sets the maximum size to 0 and prevents ...
https://dev.mysql.com/doc/refman/8.4/en/privilege-changes.html
Any user can connect and perform any operation, which is insecure. If the mysqld server is started without the --skip-grant-tables option, it reads all grant table contents into memory during its startup sequence. The in-memory tables become ...
https://dev.mysql.com/doc/refman/8.4/en/program-options.html
There are several ways to specify options for MySQL programs: List the options on the command line following the program name. This is common for options that apply to a specific invocation of the program. List the options in an option file that ...
https://dev.mysql.com/doc/refman/8.4/en/replication-bugs.html
When you have determined that there is no user error involved, and replication still either does not work at all or is unstable, it is time to send us a bug report. If you have a “phantom” problem (one that you cannot duplicate at will), use ...
https://dev.mysql.com/doc/refman/8.4/en/replication-delayed.html
Delayed replication can be used for several purposes: To protect against user mistakes on the source. The output of mysqlbinlog displays these timestamps in two formats, microseconds from epoch and also TIMESTAMP format, which is based on the user ... MySQL supports delayed replication such that a replica server deliberately executes transactions later than the source by at least a specified amount of ...