[Bucardo-general] Automatic Cascading Replication
Greg Sabino Mullane
greg at endpoint.com
Wed Dec 19 15:48:30 UTC 2012
On Tue, Dec 18, 2012 at 08:39:21PM -0800, David E. Wheeler wrote:
> Because if A goes down, frobishers won’t be updated until it comes back up.
> I want frobishers to always be as up-to-date as whatever is currently
> running in the MM “cluster.”
Frobishers (let's call it C, ok? :) will not be up to date if A goes down,
if the second sync is:
table=customers dbs=A:source B:source C:target
Bucardo cannot push out to C unless A and B are both available. What you
would need is three syncs:
1) MM between lots of tables A:source B:source
2) One-way customer table only A:source C:target
3) One-way customer table only B:source C:target
And of course customer table should have makedelta:A,B
>> We discussed on #bucardo having triggers exit if session_replication_role
>> is set to "local", and to set it to that for bulk inserts.
Well, even if one were to do this (and I am not convinced), we would
need to use seomthing other than session_replication_role. Because
setting it to "local" means that all *other* rules and triggers
would fire, something definitely not wanted.
>> Yeah, but that still means firing that trigger for every single row
>> on the bulk insert. Not so bulky anymore. :)
> I don’t know what the actual overhead on that is, do you? I mean,
> compared to the I/O required when a COPY happens, is it significant?
I don't know the numbers, no.
Greg Sabino Mullane greg at endpoint.com
End Point Corporation
PGP Key: 0x14964AC8
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