Can a Lookup field work with a list of 5000+ items? I have a list of 15000 items and I want to create a lookup column that accesses this list. Normally a lookup column will filter empty rows and return those with data (in this case 100 items - so the dataset is well within the 5000 SharePoint imposed limit). However, I'm receiving the classic "you have over 5000 items" warning message and the lookup fails because I believe it is processing the entire list. Now I've been told that I could write some code to filter the lookup (in order to work with lists over 5000 items), but I'm worried that this will not work on the 15000 item list and that I will be forced to split the list up into smaller lists (<5000 items). Does anyone have any advice?
Any help would be appreciated.
One more thing, we are SharePoint Online site so we cannot change any throttling parameters. The way we have achieved a list of more than 15,000 items is by creating sub-folders to store the items (Microsoft suggestion) within the main list.