Re: Slony vs Longiste

Robert Treat wrote:
> On Wednesday 24 September 2008 12:34:17 Jason Long wrote:
>
>> Richard Huxton wrote:
>>
>>> Jason Long wrote:
>>>
>>>> I need to set up master vs slave replication.
>>>>
>>>> My use case is quite simple. I need to back up a small but fairly
>>>> complex(30 MB data, 175 tables) DB remotely over T1 and be able to
>>>> switch to that if the main server fails. The switch can even be a
>>>> script run manually.
>>>>
>>>> Can someone either comment in as much detail as possible or point me to
>>>> a comparison of Slony vs Longiste. Or some other option I have not
>>>> heard of?
>>>>
>>> Three questions you need to ask yourself.
>>> 1. How heavily updated is the database?
>>> 2. How often do you change the database's schema?
>>> 3. Are there other databases in the installation?
>>>
>>> If #1 is "very heavy" then you'll want to do some testing with any
>>> solution you use.
>>>
>>> If #2 is "a lot" then you'll want to consider WAL shipping as mentioned
>>> below. Slony can handle schema changes, but you'll need to process them
>>> through its own script. I'm afraid I can't comment on Londiste.
>>>
>>> If you just want a backup and the answer to #3 is no, look at WAL
>>> shipping (see the various archive_xxx config settings in the manual and
>>> google a bit).
>>>
>>>
>>>> From what I read Longiste is easy to set up while I got a quote for
>>>> Slony setup for 5-10k.
>>>>
>>> Unless your requirements are strange, that seems a little high, even
>>> assuming USD as a currency. Of course, if you want support and
>>> maintenance that will tend to make things mount.
>>>
>> The database has 10-20 concurrent users so updates are not very heavy.
>>
>> The schema changes very frequently.
>>
>> There are not other databases in the installation.
>>
>> This quote included initial setup, failure testing, and scripts that
>> were to automate setup and manage the installation. It did not include
>> support and maintenance.
>>
>
> Are you planning on hiring someone to do it, or are you going to do it
> yourself, because the prices of the solution is completely orthogonal to
> which is the better fit technically.
>
> In your case, since you do a lot of DDL changes, I'd go with londiste over
> slony if I had to pick from those two. However, given the requirements you
> laid out, PITR is probably your best option (this is what Richard alluded
> too), and certainly the one I would recommend you try first.
>
>
I am looking at a combination of hiring someone for setup and advice and
them maintaining it myself.

I agree PITR is probably a good fit. How far time wise would could the
fall behind the live server and what would affect that? Anything else I
should consider if I go PITR?

The default size of WAL segment files is 16 MB. Since my entire DB is
only 30 MB(will grow quickly as I am going to add internal document
storage soon).

Will I need to recompile Postgres to reduce this? What will be the
repercussions of reducing the size?