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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 ...
https://dev.mysql.com/doc/refman/8.4/en/replication-problems.html
Many users have lost time by not doing this soon enough after encountering problems. If the receiver thread state says Connecting to master, check the following: Verify the privileges for the replication user on the source. If you have followed the ...
https://dev.mysql.com/doc/refman/8.4/en/selinux.html
An SELinux context (the label applied to a system object) has the following fields: user, role, type, and security level. Security-Enhanced Linux (SELinux) is a mandatory access control (MAC) system that implements access rights by applying a ...
https://dev.mysql.com/doc/refman/8.4/en/set-resource-group.html
For attempts to assign a system thread to a user resource group or a user thread to a system resource group, a warning occurs. SET RESOURCE GROUP group_name [FOR thread_id [, thread_id] ...] SET RESOURCE GROUP is used for resource group management ...