store the number of times a document was seen in a given time period - solr

Question

I am parsing documents on the web and storing them in solr database. Every day I see thousand of documents and some of them are repeating.
I'd like to give user an option to see which document was most seen on a given date, or in a given timespan. Queries of interest correspond to:
-show me which documents were seen the most on 16/10/2022,
-show me which documents were seen the most between 16/10/2022 and 23/10/2022
When writing solr queries, you specify field name to search on. What field type should I use and in what format should I store the number of times the document was seen on a given date?

Answer 1

How I would try it:
Create a separate collection - very simple collection with fields:
view time
doc id
title or body (whatever you're querying)
... do this for EVERY view.
you can query it by the gap you want:
curl http://localhost:8983/solr/query -d 'q=title:abc&rows=0&json.facet={
per_month: { range : {
field : last_modified,
start:'2022-01-01T00:00:00Z',
end:'2022-12-31T23:59:59Z',
gap:'+1MONTH',
}}
}}
This would return all views by MONTH (can change it to DAY, YEAR, etc).
But your doc is probably too big for this solution. If you want to normalize this:
a JOIN query. Since solr 8.6, you can now do cross-collection joins on multiple shards. this is a good article about how to do those queries. this is a decent video of how to set this up It's not that hard to do.
The JOIN query would be much faster.
If you don't want to do the JOIN query:
If the views change often, do not store them in the document store. There's no notion of partial updates in solr. If you're updating views every day, you'll need to update every document that's been viewed. That's going to cause a lot of unnecessary disk thrashing.
Other thoughts:
can you use a database? This is a far better use of views. Solr isn't good as a master record for views.
Another suggestion is to make the views go to an analytics engine - a far better solution since you can get rich analytics about the actual users. An analytics engine does a lot that rendering views does not - especially filtering out false positives (like bots!). It's not fun to maintain an accurate view count if you have a high-trafficed site.
In the past I've used an analytics engine to collect the data and used the analytics engine to export that data into solr. This way you can have the view logic be done by the software component that knows views best (the analytics engine like Google analytics or Salesforce marketing engine) and run an hourly process to update the views in solr using one of the above tactics.