MySQL 9.0 Release Notes
Table of Contents
MySQL 9.0 includes the
sys schema, a set of objects that
helps DBAs and developers interpret data collected by the
Performance Schema. sys schema objects
can be used for typical tuning and diagnosis use cases. Objects in
this schema include:
Views that summarize Performance Schema data into more easily understandable form.
Stored procedures that perform operations such as Performance Schema configuration and generating diagnostic reports.
Stored functions that query Performance Schema configuration and provide formatting services.
For new installations, the sys schema
is installed by default during data directory initialization if you
use mysqld with the
--initialize or
--initialize-insecure option. If this
is not desired, you can drop the sys
schema manually after initialization if it is unneeded.
The MySQL upgrade procedure produces an error if a
sys schema exists but has no
version view, on the assumption that
absence of this view indicates a user-created sys
schema. To upgrade in this case, remove or rename the existing
sys schema first.
sys schema objects have a
DEFINER of
'mysql.sys'@'localhost'. Use of the dedicated
mysql.sys account avoids problems that occur if a
DBA renames or removes the root account.