Re: [Postgres-xc-general] Table distribution/replication and other things

[Michael P. <mic...@gm...>]

On Thu, Jan 31, 2013 at 6:10 PM, Christophe Le Roux <
chr...@fr...> wrote:

>  Nice trick !****
>
> ** **
>
> But too complex for my brain J ( i don’t understand why tab2 is
> distributed by replication)****
>
> ** **
>
> What do you think about that (possible new feature ?) :****
>
> **-          **Possibility to create group like :****
>
> CREATE GROUPSERVER group1 (‘serverA’,’serverB’);****
>
> CREATE GROUPSERVER group2 (‘serverC’,’serverD’);
>
This already exists and is called GROUP NODE, have a look here:
http://postgres-xc.github.com/1_0/sql-createnodegroup.html


> ****
>
> ** **
>
> **-          **Possibility to table distributed an replicated like :****
>
> CREATE TABLE tab (col1 int, col2 int) DISTRIBUTE BY HASH(col1) ON
> GROUPSERVER ‘group1’ AND REPLICATE ON GROUPSERVER ‘group2’;****
>
>                 If one of these groupserver have not the same number of
> server, we have a warning message like that : “WARNING : GROUPSERVER groupX
> has not the same number of server of GROUPSERVER groupY, so we can’t
> distribute by hash, modulo  or RR but the replication on GROUPSERVER groupY
> is done.”****
>
> ** **
>
> This is like raid10 for hdd the table is splited between serverA and
> serverB and mirrored on serverC and serverD. If serverA or serverB or
> serverA and serverB fail, the table is still available with serverC and
> serverD .****
>
>
> Is it possible ?
>
Not now. At least the trick I gave before works the same with vanilla
Postgres...
This feature is a little bit too premature with existing XC infrastructure.
Such complex things would be possible by first reworking the partitioning
of XC to make it more integrated with Postgres I think.
-- 
Michael Paquier
http://michael.otacoo.com