Re: [Userops] Why is it hard to move from one machine to another? An analysis.

[Blaise Alleyne]

On 10/04/15 08:01 AM, Christopher Baines wrote:
> On 09/04/15 23:17, Dave Crossland wrote:
>>
>> On 8 April 2015 at 19:28, Christopher Baines <address@hidden
>> <mailto:address@hidden>> wrote:
>>
>>     I am currently
>>     putting off migrating my tt-rss instance because I think I might have to
>>     manually move the database across. What I really want to be able to do
>>     is just sudo apt install tt-rss on the new machine, login, and give it
>>     the credentials to the old machine, and have it do all the hard work.
>>
>>
>> What database are you using? :)
> 
> PostgreSQL
> 
>> Why not set up tt-rss on your new host, point it to the existing
>> database, and then set up a 2nd database on the new host, pair it to the
>> existing one, wait for the replication to complete, point the new tt-rss
>> to the new database, see it all working, then close the old database?
> 
> I was aware of PostgreSQL being able to do some distributed stuff, but I
> had not considered using this functionality to move a database between
> machines. I am not sure how this compares to other ways of moving the
> database, but seems a bit difficult in that I would have to to configure
> the networking and authentication, whereas at the moment, postgres is
> just on 127.0.0.1 and using ident auth.
> 

IMHO, database networking/auth stuff is only necessary if you're really trying
to minimize any downtime, but if it's acceptable to take tt-rss offline for
~15min and the tt-rss URL isn't changing, the "easiest" way would be to...
(a) dump the database to file on the on the old host;
(b) copy that dump to the new host;
(c) import the dump to the new database...

If you had apt-get installed tt-rss... I'd bet you could probably do that on the
new machine to get your database setup, but then wipe it and load the dump from
the old machine instead.

But it's not "easy" in the sense that you need to get familiar with pg_dump and
other PostgreSQL things that you may not be familiar with already.