We're trying to export a bunch of records for authority control work and we've run up against a limit where bib records greater than 100k characters don't export. In the export we're doing, item records are included so the ones that won't export are mainly the ones that have lots of items attached - many have greater than 500 items, and a few bibs have several thousand attached items.
I found that putting the bib records in a review file, and then run a separate review file of item records based on the bib record file, gets me a list of all the records that will export through data exchange. This means that I'll get 5,000 copies of the bib record, differing only in the item information attached.
I think I could probably wrestle some type of reasonable records out of this, but I'm wondering if anyone out there has managed to either find a better way to export bib records with item data that totals more than 100k characters, or found a way to get that restriction removed.