[mythtv-users] From trunk to stable...

Matt Roberts matt.roberts at bigfoot.com
Tue Nov 13 01:34:10 UTC 2007

(I'm re-sending this with an appropriate subject line)

> I'm considering to change fron svn trunk to 0.20-fixes branch.
> How about mysql database? I know, that trunk has updated database schema.
> What is easiest way to revert back? I have made much changes to settings 
> and I don't want to loose them. Also I'd like keep all data from 
> recordings, autoexpire etc.
> If I drop all tables and recreate them with mc.sql, what tables I can 
> safely recover from backup to new database? Or is there any that has no 
> changes?
> -Kane

I don't know if there's an easy way to revert back, but I can tell you what I 
did a few weeks ago after discovering that the trunk was too volatile for my 

I started with the instructions for moving data to new hardware 
(http://www.mythtv.org/docs/mythtv-HOWTO-23.html#ss23.7).  It lists the 7 
tables that are really important to preserve.  The specific steps I took (as 
I remember them) were:

1. Create a restore script as described in the "Moving Your Data to New 
Hardware" instructions
2. Create a script that will create the table structure for those 7 tables as 
they exist in the currently installed version of myth
3. Create a backup of the settings and channel tables.  These were for future 
reference only, in my case.  I didn't try to directly restore them.
4. Drop all tables
5. Uninstall 0.21
6. Install 0.20
7. Execute a myth program (mythtv-setup) so that all tables get created 
(mc.sql does not do this, it only creates the database, user, and grants some 
8. Edit the scripts created in steps 1 & 2 so they will restore the data to 
tables with a unique name.  I used '<table_name>_21', so 'recorded' 
became 'recorded_21', etc.
9. Run the create and restore scripts
10. Compare the column list of the 0.20 tables with that of the 0.21 tables 
and write some "insert into 0.20_table (select columns from 0.21_table)" SQL 
statements that only pull data from columns common to both versions.
11. Run the SQL statements created in step 10.

It worked for me.  The one thing that I have left which may be of value to you 
is my "step 10" SQL.  I assume it is still valid since I was downgrading to 
0.20.2.  Let me know if you'd like me to send it to you.


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