We're experiencing regular index corruption on a table with a partialIndexFilter, though it is not always that index getting corrupted. The only relevant thing I could find near the time when the corruption is occurring is log rotation via SIGUSR1. Nothing else in the log file seemed suspect.

Unfortunately our data is very sensitive and cannot be shared. I can tell you we're using Ruby/Rails and the mongoid_paranoia gem and set up a unique partialFilterExpression with:

	{
		"v" : 1,
		"unique" : true,
		"key" : {
			"name" : 1
		},
		"name" : "unique_active_names",
		"ns" : "api_production.app_instances",
		"partialFilterExpression" : {
			"deleted_at" : null
		}
	},

The corruption appears to have only been exposed with this added but may have happened before and gone unnoticed. We found it when being unable to find documents with this index using

{deleted_at: null, name: "name"}