Re: Regarding column reordering project for GSoc 2012

Hi all,

In follow up to my last mail, attached below, for performance, we can build
a graph with edges having weight in sense of performance wise and padding
saving wise . Then , we can build a minimal spanning tree, and the tree
generated would be our order of columns . When any changes are made ,
changes in the graph will be done and minimal spanning tree would be
recomputed.

Atri

-----Original Message-----
From: Atri Sharma [mailto:atri.jiit@gmail.com] 
Sent: 17 March 2012 22:43
To: 'Andrew Dunstan'
Cc: 'pgsql-hackers@postgresql.org'
Subject: RE: [HACKERS] Regarding column reordering project for GSoc 2012

Thanks Andrew.

I went through the link. Here is my idea:

I believe we can build a "middle" layer that encapsulates the physical
details from the user and gives him/her a VIEW that is actually generated by
the system itself. That means, we have a system such as:

LOGICAL LAYER
--------------
MIDDLE LAYER
--------------
PHYSICAL LAYER.

Now, the punch would be, the middle layer would be on the client. The middle
layer is more of an interface for the user which he/she can completely
customize.

Now, what is actually happening is that each component is mapped to their
physical address. I am planning to make a struct which will be the mapping
between the physical address and the logical address.I have not yet decided
on the design of the struct,but I plan an id , the type and the physical
address.When a component is used in the middle layer,it is represented in an
instantiation of the struct which is unchangeable throughout.Whenever we
need to customize the middle layer,we just need to reorder the components.

For our specific case,the reordering of table columns,we need not change the
schema or the physical ordering.All we need to do is,reorder the
components.One ALTER statement(with added customized clauses) will do the
reordering.The mapping remains constant,because,the struct instantiations of
the components remain constant,hence,the mapping remains constant and we can
access the physical address of any component at any time.

Please let me know your feedback on the idea.

Atri

-----Original Message-----
From: Andrew Dunstan [mailto:andrew@dunslane.net] 
Sent: 17 March 2012 21:30
To: Atri Sharma
Cc: pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] Regarding column reordering project for GSoc 2012



On 03/17/2012 04:39 AM, Atri Sharma wrote:
> Hi All,
>
> I am Atri Sharma.I am a C developer with experience in database
> designing and database management systems.I have worked with
> MySql,Oracle and other database systems.I have designed databases for
> various projects as well.
>
> I would be interested in developing the column reordering project by a
> single ALTER command.I have an idea in mind that would solve
> theproblem in a very easy way.
>
> Please let me know how to proceed further on this.
>


You should review the history on this. See 
<http://archives.postgresql.org/message-id/1324412114-sup-9608@alvh.no-ip.or
g> 
as a good place to start.


You should be aware that anything that doesn't follow the previous 
discussions is likely to be rejected. But if you can do something that 
does implement what was previously discussed, that would be awesome.

cheers

andrew