Re: scoring differences between bitmasks

From: Ben <bench(at)silentmedia(dot)com>
To: "Todd A(dot) Cook" <tcook(at)blackducksoftware(dot)com>
Cc: Martijn van Oosterhout <kleptog(at)svana(dot)org>, Postgresql-General mailing list <pgsql-general(at)postgresql(dot)org>
Subject: Re: scoring differences between bitmasks
Date: 2005-10-02 18:02:19
Message-ID: F8B339D3-2D35-4C9B-9FCC-776CA4776C87@silentmedia.com
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-general

Hrm, I don't understand. Can you give me an example with some
reasonably sized vectors?

On Oct 2, 2005, at 10:59 AM, Todd A. Cook wrote:

> Hi,
>
> Try breaking the vector into 4 bigint columns and building a multi-
> column
> index, with index columns going from the most evenly distributed to
> the
> least. Depending on the distribution of your data, you may only
> need 2
> or 3 columns in the index. If you can cluster the table in that
> order,
> it should be really fast. (This structure is a tabular form of a
> linked
> trie.)
>
> -- todd
>
>
> Ben wrote:
>
>> Yes, that's the straightforward way to do it. But given that my
>> vectors are 256 bits in length, and that I'm going to eventually
>> have about 4 million of them to search through, I was hoping
>> greater minds than mine had figured out how to do it faster, or
>> how compute some kind of indexing....... somehow.
>

In response to

Responses

Browse pgsql-general by date

  From Date Subject
Next Message Samik Raychaudhuri 2005-10-02 18:08:00 Re: Portable PostgreSQL
Previous Message Marc G. Fournier 2005-10-02 18:00:52 Re: Portable PostgreSQL