[mythtv-users] partial restore of database from backup

James Abernathy jfabernathy at gmail.com
Mon Oct 21 15:45:44 UTC 2019

On 10/21/19 11:29 AM, Stephen Worthington wrote:
> On Mon, 21 Oct 2019 10:59:06 -0400, you wrote:
>> Like many I do daily backup of my mythtv database. However, I've only
>> used that backup when building a new setup of hardware that will
>> hopefully be doing the same function as the old one, once the database
>> is restored and the recordings copied to the right directories.
>> What I'm doing now is different and not sure if the saved database can
>> help.  I'm build an additional mythtv backend that will be used to
>> record some of the same programs but it started with a clean database.
>> Both backends are set to record for example "NCIS". My main backend has
>> been recording those since the beginning of the series so when a rerun
>> comes on it will not record it again because it once recorded it long
>> ago, even though it's been watch and deleted.
>> The new backend will recorded it because it has no history.  Some of the
>> reruns are not tagged as such and using that record flag doesn't solve
>> the problem.
>> So my question is, can I export the record history of a program or all
>> programs from one backend to another so the new backend will not waste
>> time recording something that's already be seen?
>> I know that there are easy ways to just delete the recording, but I'm
>> curious if this can be done.
>> There are several reasons I want to do this, but one is I want to avoid
>> my wife deleting a program we both watch that I have not seen yet. The
>> "watched" icon doesn't always get noticed by her.
>> Jim A
> The information you want is in the oldrecorded table.  But it is not
> possible to just export that table from one database and expect it to
> work in another database as things like the chanid values will not
> refer to the same channel (unless you have also exported all the
> channel data).  If you really know what you are doing, you might be
> able to write some code that translated all the fields in the
> oldrecorded table correctly to match the new database, but it would be
> specific code for those two databases.
> If you really want to do this, the only easy way would be to create
> the new system using a full backup of the old system, then adjust its
> settings to match the new system's hardware (tuners, disk partitions,
> ...).  Then you would need delete all the data you do not need (all
> the recordings that are only on the old system, for example).  You
> could just run find_orphans.py and let it tidy up the database for all
> the missing recordings.

Thanks, I agree with your suggestion of creating a fresh system, 
restoring the system database and finding orphans.  Sound a lot easier. 
The tuners are all OTA HDHR or Hauppauge WinTV Quad tuners so the data 
on the channels should agree. they all use tv_grab_zz_sdjson_sqlite.

This is not critical, so if it screws up, I can restart the new system 
without any issues. It's a combo FE/BE on a Raspberry PI 4B 4G. At this 
point I can't find anything it can't do that my Core i7 backend can do. 
Looking for a future backend when this old PC dies.  Certainly not going 
to buy a new one for a backend as good as the Pi 4B is.

Jim A

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