title: solr boost with multivalued field and specific order key and different weight
body: <p>for example i have each document with multivalued field with fixed length</p>
  
  <pre><code>popularity: [100, 0, 0, 0, 10, 0, 0, 0, 10, 80]
  </code></pre>
  
  <p>my plan is using multiple popularity divide by region, <code>popularity[0]</code> is global, and <code>popularity[1...9]</code> is fixed with <code>region_id</code> i store in another database.</p>
  
  <p>why multivalued because the field length maybe increase if region is increase. (maybe 1 each year/3 years)</p>
  
  <p>if i using single value i can boost i.e <code>boost=log(popularity,2,5)</code>. But how i can boost if it multivalued ? i.e popularity[0]?</p>
  
  <blockquote>
    <p>i'm using solr 6.6 for prod plan to use solr 7.3.1 for next production</p>
  </blockquote>