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From Grant Ingersoll <gsing...@apache.org>
Subject Re: Payloads
Date Sat, 27 Dec 2008 17:37:24 GMT
Very cool stuff Karl.  Would love to see some TREC-style evaluations  
for the ShingleMatrixQuery stuff just to see some comparisons.  Also,  
you might have a look at the new TokenStream stuff that is in 2.9 and  
is a start on it's way towards Flexible Indexing.  I think this may  
actually allow you to have more strongly typed payloads which means  
you won't have to decode (well, kind of, Lucene will do the decoding  
for you).  Only problem is they aren't yet supported on the search  
side.  In other words, your wish for a reusable API is being worked on.

Have a look at Michael Busch's ApacheCon NO (I think it's up on the AC  
website)

-Grant

On Dec 26, 2008, at 8:22 PM, Karl Wettin wrote:

> I would very much like to hear how people use payloads.
>
> Personally I use them for weight only. And I use them a lot, almost  
> in all applications. I factor the weight of synonyms, stems,  
> dediacritization and what not. I create huge indices that contains  
> lots tokens at the same position but with different weights. I might  
> for instance create the stream "(1)motörhead^1", "(0)motorhead^0.7"  
> and I'll do this at both index and query time, i.e. I use the  
> payload weight to calculate both payload weight used by the  
> BoostingTermQuery scorer AND to set the boost in the query at the  
> same time.
>
> In order to handle this I use an interface that looks something like  
> this:
>
> public interface PayloadWeightHandler {
>  public void setWeight(Token token, float weight);
>  public float getWeight(Token token);
> }
>
> In order to use this I had to patch pretty much any filter I use and  
> pass down a weight factor, something like:
>
> TokenStream ts = analyzer.tokenStream(f, new StringReader("motörhead  
> ace of spaces"));
> ts = new SynonymTokenFilter(ts, synonyms, 0.7f);
> ts = new StemmerFilter(ts, 0.7f);
> ts = new ASCIIFoldingFilter(ts, 0.5f);
>
> All these filters would, if applicable, create new synonym tokens  
> with slightly less weight than the input rather than replace token  
> content:
>
> "(1)mötorhead^1", "(0)motorhead^0.5", "(1)ace^1", "(1)of^1",  
> "(1)spades^1", "(1)spad^0.7"
>
> I usually use 4 byte floats while creating the stream and then  
> convert it to 8 bit floats in a final filter before adding it to the  
> document.
>
> Is anyone else doing something similar? It would be nice to  
> normalize this and perhaps come up with a reusable API for this. It  
> would also be cool if all the existing filters could be rewritten to  
> handle this stuff.
>
> I find it to be extemely useful when creating indices with rather  
> niched content such as song titles, names of people, street  
> addresses, et c. For the last year or so I've done several (3)  
> commercial implementations where I try to extend the index with  
> incorrect typed queries but unique enough that it does not interfere  
> with the quality of the results. It has been very successful, people  
> get great responses in great time even though they enter an  
> "incorrect" query.
>
> On a side note, in these implementaions I've completely replaced  
> phrase queries using shingles. ShingleMatrixQuery has some built in  
> goodies for calculating weight. Combined with SSD I see awesome  
> results with very short response time even in fairly large indices  
> (10M-100M documents). I'm talking about 100ms-500ms for rather  
> complex queries under heavy load.
>
>
>      karl
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--------------------------
Grant Ingersoll

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