Manage Library Operations post reaching Threshold limit

[Arvind Gnanamani]

We have a scenario where 100,000 documents are already migrated via 3rd party tool to a document library, now we are not able to perform operations like "Break unique permission" at Document Library level.

We get "The attempted operation is prohibited because it exceeds the list view threshold enforced by the administrator" when we try to inherit via PowerShell or User Interface even with SPO Admin.

#1 - what could be the only better solution that Business Team and developer can consent to, any suggestions?
Have checked this article but always ending up in catch 22 situation.

https://support.office.com/en-us/article/Manage-large-lists-and-libraries-in-Office-365-b4038448-ec0...

#2 - Will the Search within the site or Enterprise Search bring all the content for the query or only the filter of top 5000? I always get confused here. Please note even though the count shows, 100,000 in my library still i have less than 5000 files in a folder.

#3 - Can a user view all the documents and files in All Documents view given each folder has less than 5000 items in a document library of 100,000?

[#2]

sorry to say but did you guys think of governance before migrating? 

it feels like garbage in garbage out.

I would seriously look at the documents especially as you want to break inheritance etc. you will need to have more control then just one big library.

sorry if i am wrong.

[#3]

Agree with Paul:
- Security has to be planned before doing the migration to prevent any issues such as the ones you are having.
- If you have configured views that shows less than 5.000 elements you shouldn't have any problems displaying document library documents.
- Search is a different story...could you please explain me how are you going to get the 100.000 documents doing a search :-).

[#4]

Juan/Paul - i do agree. Scenario is bit different here. Post migration we r giving access to only owners group and had to remove visitors, members until Site Owners/Business leads validate the migrated data. Once they confirm migrated data looks good, we r reseting/inheriting the parent(site) permission in document library.

Pertaining to search, assume im searching within the site for a keyword 'ASSET MANAGEMENT' which i assume there are 10 docs within the specific library that has 100,000 items, my question is will i get all the 10 in search results be it paginated or OOB ranked. Will the crawling and indexing be done be it a large library or not?

[#5]

Search will find all 10 items.

You should have had some indexes created automatically as items were added to the library. This was an improvement MS put in a while ago that improves the ability to manage large libraries like this.