If you don’t want to buy disk space for deleted docs, you should not be
using Solr. That is an essential part of a reliable Solr installation.
To avoid reindexing unchanged documents, use a bookkeeping RDBMS
table. In that table, put the document ID and the most recent successful
update to Solr.
I was reading about in-place updates
https://lucene.apache.org/solr/guide/7_4/updating-parts-of-documents.html,
In my use case I have to update the field "LASTUPDATETIME", all other
fields are same. Updates are very frequent and I can't bear the cost of
deleted docs.
If I provide all the fields,
