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Re: Ranking search results using multiple fields in PostgreSQL fulltext search

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On Mon, Oct 12, 2009 at 7:26 PM, Ivan Sergio Borgonovo <mail@xxxxxxxxxxxxxxx> wrote:
On Mon, 12 Oct 2009 19:11:01 +0530
Gaini Rajeshwar <raja.rajeshwar2006@xxxxxxxxx> wrote:

> I think you misunderstood my question. let me give clear idea
> about what i need.
>
> I am using PostgreSQL fulltext search (tsearch2) feature to
> implement searching on database. From readings i came to know that
> we can give weights to different fields in database something like
> this:
>
> *setweight(to_tsvector(title),'A')*
>
> Where 'A' is weight given to field title. i can give weights to
> other fields in the same way. Where the weights 'A', 'B', 'C', 'D'
> are in will be in the following order *A > B > C > D* according to
> defalut fulltext search configuration.
>
> We can rank the search results using ts_rank function something
> like this,
>
> *ts_rank(tsv_title,ts_query('this is my search text'))*
> **
> But, i want to rank these reults not only based on just title, but
> also using other fields like summary etc.
> Is there a way around to do this?

if you concatenate your fields with different weight in the *same*
ts_vector, ranking will take into account your weight...
yes, ranking will take into account. but how can we specify just one field at the time of searching and specify all the fields at the time of ranking?
 
Someone more knowledgeable than me chose how to use weight to give a
 
reasonable ranking.

Of course if you've field a, b and c and you want to search in a and
b only, you'll have to concatenate just a and b.

If you need different assortment in fields groups... you'll have to
add some extra redundancy if you plan to store precomputed
ts_vectors for each record.

If you need to search "separately" in different fields
(eg. title ~ 'gino' AND summary ~ 'pino')
you just need to weight the input query as well

inputquery := setweight(cfg, inputtitle, 'A', '&');
inputquery := inputquery && setweight(cfg, inputsummary, 'B', '&');
I didn't understand why did u use '&'  operator in setweight function. is that going to help in any way?

...



--
Ivan Sergio Borgonovo
http://www.webthatworks.it



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