[Postgres-xc-general] PostgreSQL-XC: error in README?

[Fernando L. <fer...@lo...>]

Hi Michael,

Found the offending text. It's in the README from many releases, 
including 1.0.0:

Postgres-XC is aiming to provide transparent access to the database, 
which means one can use existing PostgreSQL application as is. For 
implementation reason,
***transparency level is limited to access via libpq libraries***
and simple statements as found in the Architecture Document in the 
release material.

PHP, Perl and most users won't be bothered because those language 
drivers use libpq, but Java developers use a pure-java JDBC driver which 
does not uses libpq at all.

This statement on the README may be understood as "there are changes to 
libpq in postgresql-xc so you have to use our libpq. Other clients won't 
work".

But as I understand you reply, I can use any libpq to access 
postgresql-xc without problem. For example, a pgAdminIII binary for 
windows that I already use for a plain PostgreSQL server should work 
out-of-the-box with PostgreSQL-XC, or the rpm files from Debian Linux 
for a PHP app. And I could also use other clients, not based on libpq, 
such as a JDBC driver anda a .Net provider, right?


[]s, Fernando Lozano

> Hi,
>
> I spent half an hour browsing the website, wiki and docs and could not 
> find where I read that postgresql-xc should be transparent to libpq 
> clients. Will keep looking later.
>
>
> []s, Fernando Lozano
>
>
>> Hi,
>>
>> You should avoid sending responses to Postgres announce mailing lists 
>> people are going to complain. Better to use the MLs dedicated to xc.
>> Please find my answers below.
>>
>> On 2012/06/09, at 1:54, Fernando Lozano <fer...@lo... 
>> <mailto:fer...@lo...>> wrote:
>>
>>> Hi Michael,
>>>
>>> Very interesting, but the docs states that it is "transparent" only 
>>> for libpq clients. This means Java clients (using the type 4 JDBC 
>>> driver) can't use PostgreSQL XC?
>> Documentation is wrong. We tested with many drivers like php, ruby, 
>> perl, jdbc, ecpg, etc.
>> And the only problems we saw was with odbc because it uses returning 
>> and ctid. The rest was working well.
>> Could you indicate in which page the error is located?
>>>
>>> Also, as far as I understand the docs, I need something external do 
>>> implement failover if I connect to a database server which comes 
>>> offline (JBoss AS HA Datasources comes to mind), and there's no 
>>> balancer included. Am I right?
>> Yes you are right. There is a kind of load balancing between 
>> Datanodes and Coordinators by design thanks to the distributed nature 
>> of tables and the possibility to control read for replicated tables 
>> on specific nodes. However it might be preferable to have load 
>> balancing from something external.
>>
>> Regards,
>>
>> Michael
>>>
>>>
>>> []s, Fernando Lozano
>>>
>>>> Hi all,
>>>>
>>>> Postgres-XC, read&write-scalable multi-master symmetric cluster 
>>>> based on PostgreSQL, version 1.0.0 is released.
>>>> This project is seen as an open-source alternative to costly 
>>>> products such as OracleRAC. Postgres-XC is based on the code of 
>>>> PostgreSQL, so it can naturally use all its technologies, which are 
>>>> enhaunced to have a shared-nothing multi-master PostgreSQL-based 
>>>> database cluster.
>>>>
>>>> This first stable version is based on PostgreSQL 9.1.4. All the 
>>>> patches in PostgreSQL 9.1 stable branch have been merged up to 
>>>> commit 873d1c1 (1st of June 2012).
>>>> This includes the security fix related to pg_crypto dated of 30th 
>>>> of May.
>>>> You can download the source tarball directly from here:
>>>> https://sourceforge.net/projects/postgres-xc/files/latest/download
>>>> This tarball contains all the HTML and man documentation.
>>>>
>>>> 30 bug fixes have been made since release of beta2, with some 
>>>> notable enhancements:
>>>> - Support for EXTENSION is fixed
>>>> - Stabilization of the use of slave nodes in cluster
>>>> - Fix of a bug related to read-only transactions, improving 
>>>> performance by 15%.
>>>> - Support of compilation for MacOSX
>>>> About the scalability of this release, Postgres-XC 1.0.0 scales to 
>>>> a factor of 3 when compared to a standalone server PostgreSQL 9.1.3 
>>>> on 5 nodes using a benchmark called DBT-1.
>>>>
>>>> Compared to version Postgres-XC 0.9.7, the following features have 
>>>> been added:
>>>> - Fast query shipping (FQS), quick identification of expressions in 
>>>> a query that can be pushed down to remote nodes
>>>> - SERIAL types
>>>> - TABLESPACE
>>>> - Utility to clean up 2PC transactions in cluster (pgxc_clean)
>>>> - Utility for initialization of GTM (global transaction manager, 
>>>> utility called initgtm)
>>>> - Relation-size functions and locking functions
>>>> - Regression stabilization
>>>>
>>>> The documentation of 1.0, including release notes, is available here:
>>>> http://postgres-xc.sourceforge.net/docs/1_0/.
>>>>
>>>> The project can be followed on Source Forge: 
>>>> http://postgres-xc.sourceforge.net/.
>>>> And a couple of GIT repositories are used for development:
>>>> - SourceForge: 
>>>> http://postgres-xc.git.sourceforge.net/git/gitweb.cgi?p=postgres-xc/postgres-xc;a=summary
>>>> - Github: https://github.com/postgres-xc/postgres-xc
>>>>
>>>> The core team is currently working in the addition of new features 
>>>> for the next major release including:
>>>> - Merge with PostgreSQL 9.2
>>>> - Data redistribution functionality, changing table distribution in 
>>>> cluster with a simple ALTER TABLE
>>>> - New functionalities related to online node addition and deletion 
>>>> for a better user experience
>>>> - Triggers
>>>> - Planner improvements
>>>> - Global constraints.
>>>> The roadmap of the project is located here => 
>>>> http://postgres-xc.sourceforge.net/ in section Roadmap.
>>>>
>>>> The project is under the same license as PostgreSQL, now managed 
>>>> under a single entity called "Postgres-XC Development Group".
>>>> In order to keep in touch with the project, whose development 
>>>> follows the same model as PostgreSQL, you can register to the 
>>>> following mailing lists:
>>>> - pos...@li... 
>>>> <mailto:pos...@li...>, for general 
>>>> questions. Registration can be done here: 
>>>> https://lists.sourceforge.net/lists/listinfo/postgres-xc-general
>>>> - pos...@li... 
>>>> <mailto:pos...@li...>. hachers 
>>>> mailing list. Registration can be done here: 
>>>> https://lists.sourceforge.net/lists/listinfo/postgres-xc-developers
>>>>
>>>> See you soon on the project mailing list, and have fun with this 
>>>> stable release.
>>>> -- 
>>>> Michael Paquier
>>>> Member of core team of Postgres-XC, and Postgres-XC Development Group
>>>
>>>
>
>