Query Re-Ranking allows you to run a simple query A for matching documents and then re-rank the top N documents using the scores from a more complex query B.

Since the more costly ranking from query B is only applied to the top N documents, it will have less impact on performance then just using the complex query B by itself. The trade off is that documents which score very low using the simple query A may not be considered during the re-ranking phase, even if they would score very highly using query B.

For more info see https://solr.apache.org/guide/query-re-ranking.html.

Options

Name	Type	Default value	Description
query	string	null	The query string for your complex ranking query.
docs	integer	200	The number of top N documents from the original query that should be re-ranked. This number will be treated as a minimum, and may be increased internally automatically in order to rank enough documents to satisfy the query (i.e., start+rows).
weight	float	2.0	A multiplicative factor that will be applied to the score from the reRankQuery for each of the top matching documents, before that score is added to the original score.
scale	string	null	Scales the rerank scores between min and max values. The format of this parameter value is min-max where min and max are positive integers.
mainscale	string	null	Scales the main query scores between min and max values. The format of this parameter value is min-max where min and max are positive integers.
operator	string	add	The operator determines whether the re-ranked score is added to, multiplied by, or replaces the original score. Use one of the OPERATOR_* class constants as value.

Example

<?php

require_once(__DIR__.'/init.php');
htmlHeader();

// create a client instance
$client = new Solarium\Client($adapter, $eventDispatcher, $config);

// get a select query instance
$query = $client->createSelect();
$query->setQuery('electronics');

// get rerankquery component
$rerank = $query->getReRankQuery();

// boost documents that have a popularity of 10
$rerank->setQuery('popularity:10');

// set the "boost factor"
$rerank->setWeight(3);

// set the scale for the rerank scores
$rerank->setScale('0-1');

// set the scale for the main query scores
$rerank->setMainScale('0-1');

// multiply the original score by the re-ranked score
$rerank->setOperator($rerank::OPERATOR_MULTIPLY);

// this executes the query and returns the result
$resultset = $client->select($query);
// display the total number of documents found by Solr
echo 'NumFound: '.$resultset->getNumFound();

// show documents using the resultset iterator
foreach ($resultset as $document) {

    echo '<hr/><table>';

    // the documents are also iterable, to get all fields
    foreach ($document as $field => $value) {
        // this converts multivalue fields to a comma-separated string
        if (is_array($value)) {
            $value = implode(', ', $value);
        }

        echo '<tr><th>' . $field . '</th><td>' . $value . '</td></tr>';
    }

    echo '</table>';
}

htmlFooter();