[Bucardo-general] Swap replication latency
abalashov at evaristesys.com
Fri May 6 01:30:17 UTC 2011
P.S. I think the reason it can't catch up at a normal pace is because
it takes me about ~5 minutes to add the table to the sync, run the 'add
sync' command (which entails a validate_sync()), and then start it.
During that time, as many as several thousand net deltas happen, and so
in order to catch up Bucardo would have to operate at a transactional
throughput that is fast enough to both catch up to the changes
accumulated during the sync reinitialisation + stay on top of new ones
at the same pace. Evidently it cannot do that, at least as tuned by
So, is there a way I can turbocharge it?
On 05/05/2011 09:27 PM, Alex Balashov wrote:
> 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
> 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
> 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?
Alex Balashov - Principal
Evariste Systems LLC
260 Peachtree Street NW
Atlanta, GA 30303
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