Using a Cross-site Lookup to a SharePoint list with an exceeded threshold limit

In SharePoint there is a default limit of 5000 items that you can add to a list until you are unable to filter that list. For more information on this see here.

What this means in practice is that you are unable to use a SharePoint Cross-site Lookup field that points to a list with an exceeded threshold. In this article we will describe a way of how you can go around the problem.

Note that in SharePoint On-Premises you can increase the threshold limit, for that you can check this article (it’s for SharePoint 2010, but 2013 is the same).

If you cannot or don’t want to change the limit, follow this procedure:

1. Index the columns that your use to filter the list items by. Here you should include any fields you’re using in the filter=… part of the query (go to Manage Plumsail Lookups → Request items to see code that returns the two queries)
2. Remove the orderby parameter from the first query (note the lack of the orderby parameter in the following example):

function (term, page) {
  if (!term || term.length == 0) {
    return "{WebUrl}/_api/web/lists('{ListId}')/items?$select=Id,{LookupField}&$top=10";
  }

  return "{WebUrl}/_api/web/lists('{ListId}')/items?$select=Id,{LookupField}&$orderby={LookupField}&$filter=startswith({LookupField}, '" +
    encodeURIComponent(term) + "')&$top=10";
}