Search Framework - updating 'Document Level security' with Incremental indexing.

We are in the process of developing keyword search functionality with 'document level security' (search definition > security tab) enabled and is working as expected in Test environment.

But thinking of PRD, where we need to index 120mil+ rows (and growing) as part of one of 'Full index' and have dynamic role allocation functionality as well as frequent changes to end user roles and row level security, which drives what rows of data end users can access.

The full index of 120mil+ rows may take many hours (knowing Build Search Index > 'Date Range' feature can be used for parallel indexing to reduce the indexing times, although initial runs in test environment shows that the some of the rows are not being indexed, though further investigations as to why needs to occur) having known it 35 mins to index 14400 rows. range, we will be scheduling incremental indexing process to index updates.