[Bucardo-general] Latency on delete
Alex Balashov
abalashov at evaristesys.com
Fri Jan 17 16:27:39 UTC 2014
On 01/17/2014 11:09 AM, Greg Sabino Mullane wrote:
> On Fri, Jan 17, 2014 at 10:15:20AM -0500, Alex Balashov wrote:
>> How long is a DELETE of ~4.5 million rows (in a relatively narrow
>> table) supposed to take in a scenario with a simple pushdelta
>> replication setup?
>
> That's a lot of rows. Your best bet is to make sure you are logging
> long queries at the Postgres level (e.g. setting log_min_duration_statment = 500),
> and then see the exact queries that are taking up most of the time.
Yeah, I hear you. In fact, I'm not even sure this is a Bucardo issue
per se, and I would expect any deletion of so many rows to churn for a
while.
But still, am I right to assume that the deletion of any given row won't
return, as a statement, until the trigger that pushes that delta into
the Bucardo tables returns? It's a fairly "synchronous" process, right?
I haven't tried that deletion with the Bucardo delta triggers disabled,
and given that this is a production system, it'd be kind of challenging
to do that. But I agree with you that slow statement logs would
probably illuminate the problem better, and will go down that avenue.
> If you are using the latest Bucardo and going to multiple targets,
> I just pushed an optimization that should help that case, so git pull
> and try again :)
I'm not, I'm using the 4.5.0 tarball from the web site. What's the
optimisation?
-- Alex
--
Alex Balashov - Principal
Evariste Systems LLC
235 E Ponce de Leon Ave
Suite 106
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Tel: +1-678-954-0670
Web: http://www.evaristesys.com/, http://www.alexbalashov.com/
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