rsync - May 2008 - taking advantage of filles in folder other than destination folder

Dear Folks,

I have to backup pgsql database dump everynight on a routine. The database
dump actually contains sql(text) statements. The actual size of the database
dump is aroung 800 MB. Between two days backup, only few lines of statements
are modified/added/deleted. 

I dont want to do incremental backup. Instead, I want everyday's full dump
to be stored on to a folder named DD-MM-YY(ex: 01-05-08). Everyday there
will be a folder created with name DD-MM-YY and the dump will be stored
there.

Since the difference between the two day's backup are pretty minimal, I dont
want to resend the 800 MB files everyday. 

Suppose, 

1. I have taken yesterdays dump in a folder named 04-05-08 in database
server
2. I have rsynced the folder 04-05-08 to the backup server.
3. I have taken today's dump in folder named 05-05-08 in database server.
4. Now while doing rsync, I want rsync to compare the <database server's
05-05-08/dump file>  with the <04-05-08/dump file> which already exists
in
backup server. (then eventually,  I want rsync to send only the differences
and store the output in folder 05-05-08).

Typicaly I want to take advantage of yesterday's file which already present
in a different folder. 

Can anyone suggest a working method to implement this ? (I tried --copy-dest
/ --compare-dest .. but couldnt get it to work)

Any response in this regard is most appreciated.

Regards,
rssrik
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On Mon 05 May 2008, rssrik wrote:
> Suppose, 
> 
> 1. I have taken yesterdays dump in a folder named 04-05-08 in database
> server
> 2. I have rsynced the folder 04-05-08 to the backup server.
> 3. I have taken today's dump in folder named 05-05-08 in database
server.
> 4. Now while doing rsync, I want rsync to compare the <database
server's
> 05-05-08/dump file>  with the <04-05-08/dump file> which already
exists in
> backup server. (then eventually,  I want rsync to send only the differences
> and store the output in folder 05-05-08).
> 
> Typicaly I want to take advantage of yesterday's file which already
present
> in a different folder. 
> 
> Can anyone suggest a working method to implement this ? (I tried
--copy-dest
> / --compare-dest .. but couldnt get it to work)
Something like this should work...

BASE=/backup/psql # edit for your situation
REMOTESOURCE=dbhost::psqldumps/ # again, edit
TODAY=`date +%d-%m-%y`  # I prefer %Y-%m-%d, sorts better
cd $BASE
YESTERDAYS_BACKUP=`ls -td ??-??-?? | head -n 1`
rsync -a --compare-dest=../$YESTERDAYS_BACKUP $REMOTESOURCE $TODAY/


Paul Slootman