Hi, and thanks for the response.  I sent this months ago so it's nice to see it!

We don't use pg_dump to back up.  We use SELECT pg_start_backup('label'); to track the WAL files, and 
we tar up all our data files and put those onto tape (using a logical volume snapshot to keep the 
backup consistent).

If I needed an exact table output as a backup instead of files, I would use "copy out" in binary mode 
(which it has) for my tables.  I don't know that that is fundamentally better than text, when I really 
get to thinking about it, past a certain decimal place.  My grasp of binary versus text here is not 
what I'd like, but maybe you guys can shed more light on this?  How much accuracy are we really 
getting with text copying?

Thanks,
Jennifer


Christopher Browne wrote:
> Jennifer Spencer <jennifer at sun.Stanford.EDU> writes:
>> Hi All -
>> I am new to Slony-1.  I have searched the archives for the last six
>> months and haven't seen anything about this topic, so I am going to
>> ask.
>>
>> We are hoping to set up Slony-1 log shipping from our shop to a few
>> others.  My shop is part of a science mission in the Physics Lab.  A
>> lot of our data, essential for science, is stored as "double".  We
>> need to be able to log ship that science data.
>>
>> But, from what I can tell so far, Slony-1 log shipping only uses the
>> Plain Text format for its shipped logs.  True or false?  If false, how
>> do I specify binary or any other format?
> 
> Log shipping uses the same format as regular replication, namely the
> plain text form of the Insert/Update/Delete queries.  There is no
> option of specifying another format.
> 
>> If we must use plain text to log ship, what kind of accuracy can we
>> expect for data type 'double', or 64 bit floating point numbers
>> contained in that log?
> 
> If it *isn't* faithfully replicating the values that are stored, then
> you'll have much the same problem with any backups you might do, as
> the typical pg_dump also uses Plain Text format for such data.
> 
> Thus, if you *are* in trouble (and it is by no means obvious to me
> that you are), you were in trouble long before Slony-I got involved.