postgres-xc-general Mailing List for Postgres-XC

On Wed, Jan 23, 2013 at 7:03 AM, Steven Vaughan <
ste...@da...> wrote:

>
>   Howdy all, I was wondering if all node entries (manually managed by
> CREATE NODE... ) were manually created or if there was some automation in
> the background that kept the pgxc metadata table up to date?  (For
> instance, when a datanode connected to the gtm?)
>
You need to do that manually or with an external manager tool.
-- 
Michael Paquier
http://michael.otacoo.com

  Howdy all, I was wondering if all node entries (manually managed by
CREATE NODE... ) were manually created or if there was some automation in
the background that kept the pgxc metadata table up to date?  (For
instance, when a datanode connected to the gtm?)

Thanks in advance,
-steve

Ashutosh, Michael - thank you both for explanations, I really appreciate it.

Very good it is not the same thing as in pgpool :-)

regards,
Filip



On Mon, Jan 21, 2013 at 10:25 PM, Ashutosh Bapat
<ash...@en...> wrote:
> On Tue, Jan 22, 2013 at 3:41 AM, Filip Rembiałkowski
> <fil...@gm...> wrote:
>> Hi PG-XC authors.
>>
>> I am reading the PGCon2012 Tutorial presentation
>> [ http://postgresxc.wikia.com/wiki/File:20120515_PGXC_Tutorial_global_1.pdf ]
>>
>> Thank you for this document - it really covers many things.
>>
>> On page 44 you write about data distribution, and using distributed
>> tables versus replicated tables.
>> You use the term "Statement based replication" - and this alerted me instantly.
>>
>
> statement based replication simply means that data is replicated using
> SQL statements as opposed to WALs etc. These statements are generated
> at the coordinator, while planning the query. Postgres-XC is
> intelligent enough to understand which parts of original DML can be
> evaluated at the datanodes and which are not and it generates the
> statements by feeding values for the parts that need evaluation at
> coordinator (like volatile functions). So the problems like pgpool do
> not occur in Postgres-XC.
>
>> What _exactly_ did you mean by this?
>>
>> As you probably know, pgpool project uses exactly same term, and for
>> them it means sending same statement to many parallel nodes.
>> This approach is proven to be flawed by design - at least when you use
>> any volatile functions when writing, it makes replicas inconsistent.
>>
>> Thanks,
>> Filip
>>
>> ------------------------------------------------------------------------------
>> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS,
>> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current
>> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft
>> MVPs and experts. SALE $99.99 this month only -- learn more at:
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>> _______________________________________________
>> Postgres-xc-general mailing list
>> Pos...@li...
>> https://lists.sourceforge.net/lists/listinfo/postgres-xc-general
>
>
>
> --
> Best Wishes,
> Ashutosh Bapat
> EntepriseDB Corporation
> The Enterprise Postgres Company

On Tue, Jan 22, 2013 at 3:41 AM, Filip Rembiałkowski
<fil...@gm...> wrote:
> Hi PG-XC authors.
>
> I am reading the PGCon2012 Tutorial presentation
> [ http://postgresxc.wikia.com/wiki/File:20120515_PGXC_Tutorial_global_1.pdf ]
>
> Thank you for this document - it really covers many things.
>
> On page 44 you write about data distribution, and using distributed
> tables versus replicated tables.
> You use the term "Statement based replication" - and this alerted me instantly.
>

statement based replication simply means that data is replicated using
SQL statements as opposed to WALs etc. These statements are generated
at the coordinator, while planning the query. Postgres-XC is
intelligent enough to understand which parts of original DML can be
evaluated at the datanodes and which are not and it generates the
statements by feeding values for the parts that need evaluation at
coordinator (like volatile functions). So the problems like pgpool do
not occur in Postgres-XC.

> What _exactly_ did you mean by this?
>
> As you probably know, pgpool project uses exactly same term, and for
> them it means sending same statement to many parallel nodes.
> This approach is proven to be flawed by design - at least when you use
> any volatile functions when writing, it makes replicas inconsistent.
>
> Thanks,
> Filip
>
> ------------------------------------------------------------------------------
> Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS,
> MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current
> with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft
> MVPs and experts. SALE $99.99 this month only -- learn more at:
> http://p.sf.net/sfu/learnmore_122412
> _______________________________________________
> Postgres-xc-general mailing list
> Pos...@li...
> https://lists.sourceforge.net/lists/listinfo/postgres-xc-general



-- 
Best Wishes,
Ashutosh Bapat
EntepriseDB Corporation
The Enterprise Postgres Company