Date: Fri, 26 Aug 2005 11:04:59 -0500
From: Frank Wiles <frank@wiles.org>
To: gxlists@gmail.com
Cc: pgsql-performance@postgresql.org
Subject: Re: Sending a select to multiple servers.
Message-Id: <20050826110459.03cce4d9.frank@wiles.org>
In-Reply-To: <20050826152409.GA22060@lxlabs.com>
References: <20050826152409.GA22060@lxlabs.com>
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On Fri, 26 Aug 2005 20:54:09 +0530
Ligesh <gxlists@gmail.com> wrote:

> 
>  I would like to know if the following kind of database client exists:
>  I need a 'select' query to be sent to say 10 db servers
>  simultaneously in parallel (using threading), the results should be
>  re-sorted and returned. For example I have a query: 'select * from
>  table where parent_clname = 'parent' order by name limit 10'. Now
>  this query has to be sent to 10 servers, and the maximum number of
>  results would be 100. Now this 100 result set has to be re-sorted,
>  out of which 90 has to be discarded, and the 10 has to be returned.
> 
>  Does such a solution exist now. To me this appears to be in entirety
>  of what should constitute a database cluster. Only the search needs
>  to be done on all the servers simultaneously at the low level. Once
>  you get the results, the writing can be determined by the upper level
>  logic (which can even be in a scripting language). But the search
>  across many servers has to be done using proper threading, and the
>  re-sorting also needs to be done fast. 

  This is typically handled by the application layer, not a standard
  client.  Mostly because every situation is different, you may have
  10 servers and need 10 rows of results, others may need something
  entirely different. 

  This isn't really a "cluster" either.  In a clustered environment
  you would send the one query to any of the 10 servers and it would
  return the proper results. 

  But like I said this type of application is fairly trivial to write
  in most scripting or higher level languages. 

 ---------------------------------
   Frank Wiles <frank@wiles.org>
   http://www.wiles.org
 ---------------------------------