[mythtv-users] Upgraded to Ubuntu 22.04 / MythTV 32 - MythWeb search now abysmally slow

Gary Buhrmaster gary.buhrmaster at gmail.com
Fri Sep 29 14:37:32 UTC 2023


On Fri, Sep 29, 2023 at 11:49 AM Will Dormann <wdormann at gmail.com> wrote:

> I'm not exactly sure why upgrading mysql versions (as part of the Ubuntu
> 22.04 upgrade) would have affected anything related to database
> optimization.  But it's back to normal now!

Did you upgrade your database instance (and, of course,
ran mysql_upgrade), or restore from a backup?

If you restored from a backup the database would
not have the necessary table statistics to choose
an optimal plan for the query (so, often full table
scan).  And if the database upgrade is between
a large enough version difference the table
statistics table may also be cleared or requires
one to create new table statistics (the release notes
between the two versions of mysql would likely
have mentioned that, but you would need to read
them all from where you were, to where you are,
which is, of course, good practice).

It is DBA 101 to expect to need to both
validate the database integrity and refresh
table statistics when upgrading the database
engine more then a minor patch release
unless the vendor states otherwise (and
then you often do it anyway, because the
vendor does not necessarily understand
your environment).


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