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README.md

OldDog

The repository contains the code that accompanies the blog post Teaching An Old Dog a new Trick.

Preliminaries

olddog is build using maven:

mvn clean package appassembler:assemble

OldDog takes a Lucene index as input, for example as created by the Anserini project. The Robust 04 collection can be indexed as explained on this Anserini page.

Setup

After creating the index, the CSV files representing the database tables can be created issuing the following command:

nohup target/appassembler/bin/nl.ru.convert.Convert -index path/to/index -docs /tmp/docs.csv -dict /tmp/dict.csv -terms /tmp/terms.csv

This creates multiple files that represent the columns of the docs, dict and terms tables as described in the blog post.

The column store relational database MonetDB can load these files using the COPY INTO command.

Usage

After this final step it is possible issue the query described in the post:

WITH qterms AS (SELECT termid, docid, df FROM terms                             
  WHERE termid IN (10575, 1285, 191)),                                          
  subscores AS (SELECT docs.docid, len, term_tf.termid,                         
  tf, df, (log((528155-df+0.5)/(df+0.5))*((tf*(1.2+1)/                          
  (tf+1.2*(1-0.75+0.75*(len/188.33)))))) AS subscore                            
  FROM (SELECT termid, docid, df AS tf FROM qterms) AS term_tf                  
  JOIN (SELECT docid FROM qterms                                                
    GROUP BY docid HAVING COUNT(distinct termid) = 3)                           
    AS cdocs ON term_tf.docid = cdocs.docid                                     
  JOIN docs ON term_tf.docid=docs.docid                                         
  JOIN dict ON term_tf.termid=dict.termid)                                      
SELECT scores.docid, score FROM (SELECT docid, sum(subscore) AS score           
  FROM subscores GROUP BY docid) AS scores JOIN docs ON                         
  scores.docid=docs.docid ORDER BY score DESC;

Team

Chris Kamphuis and Arjen de Vries.

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