[Pgpool-general] Applicability of PgPool-II / PgPool-HA in WAN

[Tatsuo Ishii]

> Hi there,
> I have some question considering the applicability of SkyTools in
> special situations.

I'm not familiar with SkyTools at all, but...

> Ability to provide WAN replication.
>  - Is it possible to use PgPool-II (PgPool-HA) in wide-are network (WAN)
> enviroment ?
> The bandwidth on the master-master link is 34 Mbit/sec, on the
> master-slave link 10 MBit/sec. Both sides will have a latency of 30msec.

I'm not sure what the master-master link or master-slave link means,
but one of a users uses pgpool-II with two DB nodes, one is in
Australia, the other is in the US.

> Robustness concerning network drop out.
>  - Can two master nodes - which are not continuosly connected - be used
> ?

If pgpool-II detects connection failure to DB nodes, it will
immediately disconnect the failed DB.

> Data consistency. In this scenario, the two master nodes are
> unconnected, changes are made and new primary-key values are generated
> at both sites.
>  - How does PdPool-II act by time the master nodes are reconnected ? How
> about conflict resolution in the case of newly introduced, equal
> PK-values at each (unconneted) site ?

Again, I'm not sure if I understand the question, but... if two
pgpool-II connect to DB nodes, they will act as if two independent
psql connect. i,e. the first transaction will succeed in inserting the
PK value. The latter will fail with PK violation error.

> I'd like to appreciate any response to my open questions.
> 
> Thank you very much,
>  Martin
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