[Bucardo-general] Swap replication latency

[Alex Balashov]

I've troubleshot this some more on our side by process of elimination of 
synced tables, and what I found is that the sync time trends back toward 
a normal 5-6 sec when all tables that are modified at a high volume are 
excluded.

As a test, I added one of the high-volume tables, which was doing 
roughly ~2000 UPDATEs every 10 minutes, and maybe 300 INSERTs during the 
same time frame.  Bucardo fell way behind to a 11+ minute sync run time, 
and the delta table started blowing up.

These statements do not take any appreciably long time to run.  Yeah, 
they're not the fastest thing ever, but the point is that both database 
servers can easily handle the load.  So the bottleneck really is 
Bucardo, not the target database server;  the hardware is identical, and 
the target server's load average constantly hangs around ~0.01, and the 
source database server isn't exactly breaking a sweat either.  We have 
Postgres set to log queries over 15 ms and are getting hardly any 
complaints.

Thus, I can only come to the conclusion that Bucardo is not spinning 
nearly hard enough.

So the question is, what--if any--parameters can I tweak to make 
Bucardo's transactional throughput faster?  Preferably several times 
faster.  Is it even possible, or is this basically a low-speed 
replication system and there is not much that can be done here?

Thanks,

-- 
Alex Balashov - Principal
Evariste Systems LLC
260 Peachtree Street NW
Suite 2200
Atlanta, GA 30303
Tel: +1-678-954-0670
Fax: +1-404-961-1892
Web: http://www.evaristesys.com/