Re: What do you know about the btclean thread

The btclean cleans up the index entries which have been marked for deletion. It is normally asleep untill it is activiated by another thread. There is a queue containing a list of all leaf pages which have items marked for deletion. When the btclean thread is activated, it runs the list and removes any index item marked for deletion, if the transaction which deleted it is no longer active. Update statistics will also do the same thing. This is part of the way that adjacent index key locking is avoided in 7.x