[mythtv-users] DB manipulation

[Mark Perkins]

> On 6 Aug 2014, at 1:25 am, "Daryl McDonald" <darylangela at gmail.com> wrote:
> 
> 
> On Aug 5, 2014 12:22 AM, "Michael T. Dean" <mtdean at thirdcontact.com> wrote:
> >
> > On 08/04/2014 05:58 PM, Doug Lytle wrote:
> >>
> >> Daryl McDonald wrote:
> >>>
> >>> Would it work to create the backup, restore it to the new system, then "mythconverg_restore.pl <http://mythconverg_restore.pl> --change_hostname --old_hostname="XXXX" --new_hostname="YYYY" it?
> >>
> >>
> >> Yes
> >
> >
> > Iff you run the --change_hostname before you run any MythTV application at all on the new system, and iff you have never run any MythTV application on any system that used the new same host name as the new host name.
> >
> > Mike
> >
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> 
> I'm guessing that you are saying that since I've set up the BE and added scripts etc., it won't work because I have already created a Db. In that case, would I have to drop the current Db before restoring the previous system's Db?
> Daryl
> _______________________________________________

No, when a system (frontend or 'slave' backend) first connects to the master backend the master backend populates a heap of default settings into the database which are all keyed off the host name. They will essentially remain in the database for ever. What the --change_hostname command does is change all the settings from an old hostname to a new hostname. However if the new hostname has already been used (at some time in the past) then the --change_hostname command would result in some settings being duplicated which is not permitted under the database rules so the change would fail.

I guess that the script fails gracefully (ie checks if the proposed new hostname has been used before and refuses to proceed if it has) rather than getting half way through and then corrupting your database but either way make sure you have a known good backup of your database and keep it some place very safe....

If you have been able to successfully restore your database during your testing so far then just keep doing whatever you have been doing to restore the database. Just make sure that no myth% program runs on the new system and touches the database before the change hostname script has been run. Note MySQL will need to be running with the database restored for the script to work.
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