The bad page splits are the splits that we learned in the previous post which is the split that occurs when a random insert has to happen and there is no space on page, a new page gets created during the page split. These page splits are very expensive causing the fragmentation. Good page splits occurs when the append only inserts happen as the pages gets filled on the index pages to the right side of the index and new pages gets added as they gets filled up to the right side of the index. These types of good page splits doesn’t cause any index fragmentation. SQL Server will group these two types of page splits together and do not differentiate between them. So, how do we know to differentiate between the good and the bad page splits? Let’s learn more about this.
It is very difficult to differentiate these page splits by using the existing methods we have in the SQL Server like using the perfmon counter which has the pagesplits/sec counter. This counter will give the good and the nasty page splits together. There is a DMV sys.dm_db_index_operational_stats and an extended event page_split event to track the page splits.
Read on to see how we can find those undesirable page splits versus the benign ones.