[mythtv-users] Schema upgrade from 0.21->0.24_fixes hangs

[Josh Mastronarde]

On Tue, May 31, 2011 at 5:30 PM, Michael T. Dean
<mtdean at thirdcontact.com> wrote:
> On 05/31/2011 07:31 PM, Josh Mastronarde wrote:
>> Sorry about the last message; I tried to cut the size down to the
>> allowed limit, but pasted (very) wrong.  Trying again:
>>
>> Well, I'm back to thinking there's a Myth related issue -- I tracked
>> the mysql performance problem to being ext4 related; added "barrier=0"
>> to the mount options and the test case runs as fast as I'd expect now.
>> However, the Myth schema upgrade, either through mythtv-setup or
>> mythbackend, still hangs on the first step (1215->1216; it wants to go
>> to 1264).  I ran "mythbackend -v all", and the logs are attached
>> below.  There's a lot of activity, including database activity in the
>> first minute, then nothing after the "Upgrading to MythTV schema
>> version 1216" line; I let it sit for 6 hours last night and no further
>> log updates appeared.
>>
>> Any ideas where to look?
>
> Best guess is that your MySQL server or file system is misconfigured or
> your MySQL user permissions are incorrect such that you can't create
> temporary tables.  This can happen if you have a bad temp directory
> specified for MySQL or if your temp directory file permissions are wrong
> or if you haven't granted necessary permissions (ALL) to the MySQL user
> MythTV uses.

Thanks; it may/must be a configuration issue, but I couldn't figure
out what -- the permissions and ability to create temp tables manually
as the mythtv mysql user all seemed okay.  I let it run overnight, and
it did eventually finish...after 8 hours.  I added some custom log
lines to mythdbcon.cpp:

2011-05-31 22:39:29.496 Josh in exec calling QSqlQuery: ALTER DATABASE
mythconverg DEFAULT CHARACTER SET latin1;
2011-06-01 06:39:22.519 Josh after QSqlQuery

Those lines are immediately before and after a single call to
QsqlQuery::exec (which I believe is part of the QT library?); that
call is taking 8 hours.  After that, the rest of the upgrade all the
way to 1264 takes less than a minute and seemed to succeed (running
mythtv-setup now goes straight to the menu screen).  When I ran that
line manually in mysql before letting mythbackend run all night, it
completed instantly, so I have no idea why that one call is an issue.

I did have some confusion when initially running with getting the
right qt-mysql package installed, so that could be related.  I will
probably reinstall the OS from scratch for another purpose anyway, so
will see if the issue reoccurs.  I will, of course, save this upgraded
database just in case :-)

Thanks,

Josh