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Re: Indexing for Expression type data using GIST

From: Wizard Shah <wizardshah(at)hotmail(dot)com>
To: Martijn van Oosterhout <kleptog(at)svana(dot)org>
Cc: <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Indexing for Expression type data using GIST
Date: 2008-03-27 19:57:29
Message-ID: BAY137-W11B8F09AF319745ADD3BAFCEFE0@phx.gbl (view raw or flat)
Thread:
Lists: pgsql-hackers
Hi, 

The information is a simple structure with a string and integer. It basically represents what attributes of the expression are going to be part of the index

struct ExpIndexInfo
{
    int count;
    char* ExpIndex;
};

e.g we have an expression data like  "price > 1300 AND color = blue AND mileage > 20000" and the index will include only the price and mileage attributes. The string "ExpIndex" will contain the attributes to be indexed (price and mileage) and  integer "count" maintains the max number of attributes to be indexed on the expression. This is all to be specified at the index creation time and stored in the Meta-Data to be changed or retrieved later

Regards

Salman



> Date: Thu, 27 Mar 2008 20:34:04 +0100
> From: kleptog(at)svana(dot)org
> To: wizardshah(at)hotmail(dot)com
> CC: pgsql-hackers(at)postgresql(dot)org
> Subject: Re: [HACKERS] Indexing for Expression type data using GIST
> 
> On Thu, Mar 27, 2008 at 02:03:09PM -0500, Wizard Shah wrote:
> > Hi All,
> > 
> > I am trying to implement indexing mechanism for the Expression type
> > data using GIST. For that purpose I need to store some extra
> > information in the Meta-Data of the GIST Index.
> 
> There is no real provision for this but, depending on what it is there
> may be other options. For example perhaps you can use the typmod or
> something like that.
> 
> > The information is entered when the index is created on the table.
> > Can any body give me some suggestion how to do that. I'll be really
> > grateful.
> 
> If you provide some more information about what the information
> represents we might be able to give you a better idea.
> 
> Have a nice day,
> -- 
> Martijn van Oosterhout   <kleptog(at)svana(dot)org>   http://svana.org/kleptog/
> > Please line up in a tree and maintain the heap invariant while 
> > boarding. Thank you for flying nlogn airlines.

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