dm_db_stats_histogram missing row when column/histogram step contains NULL
When statistics on a nullable column contain a NULL sys.dm_db_stats_histogram will not return a row for the corresponding histogram step (when RANGE_HI_KEY is a NULL). DBCC SHOW_STATISTICS returns all steps including the aforementioned missing one. Without all the histogram levels dm_db_stats_histogram is not usable.
I can confirm this behaviour with INT and VARCHAR columns, I haven't tested other data types). I have attached the reproduction code and a screenshot. Any questions please let me know. Thank you.
SQL Version: 14.0.3025
Gary Harding commented
Agree, the missing histogram step for NULL values contains useful information in the equal_rows column.
Without it, the DMO is not a complete replacement for DBCC SHOW_STATISTICS, which I imagine was the intention.