Item permissions based on field

Question

how can I do list with about 16000 items, which can view and edit only about 2500 users (every only its items, so about 6...). It would be based on column with user number. I found for example this article https://www.portalfronthosting.com/blog/sharepoint-item-permissions-based-on-column-value, but every solutions says, that i have to do about 2500 different adjustments (folders, workflow conditions)

So I would like to do it programatically (http://sharepoint.infoyen.com/2012/03/13/setting-list-item-permissions-programatically-in-sharepoint/). All the items have the same permissions, but script compares logged in user with specific column and hide/disable items where it won´t be his number. I don´t want to set permission to items individually (due to workflow) because it become very slow:(

Answer 1

You can change the Created By field to the correct user with any script (CSOM, PowerShell, JSOM)

You can tthen use:

Item Level Security can be set on LISTs (List Settings -> Advanced Settings)

As SharePoint is primarily used as a DMS and setting this on (large) Document Libraries can cause performance issues it was most likely removed from the UI.

Using PowerShell you can set this on Document Libraries also:

$spList.ReadSecurity=2 
# 1=read all items
# 2=read items created by user

$spList.WriteSecurity=4 
# 1=Create and edit All items
# 2=Create items and edit items that were created by the user
# 4=None

$spList.Update()

Answer 2

Here is something you can try without the need to set item level permissions

1. Enabled audience targeting on the list using list settings

2. Use a content query webpart to get items from the list and by filtering the content using audience targeting