This may be insignificant, but some us dinosaurs still remember when you had to do everything possible to improve disk performance (not so much an issue now), and old habits are hard to break.
Specifically, this is about the IgnoreNulls property on indexes. I generally keep it set to false, but I’m wondering if it should be set to True sometimes. Access Help mentions setting this to True if there are alot of null entries in a table as it will reduce the index size. This generally is a good thing, and usually will help performance.
However, I’m thinking that it should NOT be set to True if you often use “Is Null” as a selection criteria, or if you are often sorting on this field and expect Nulls to be grouped together. It seems that in either of those situations, Access couldn’t use the available index (if IgnoreNulls was True), and would have to look at all records. (I’m assuming, or perhaps hoping, that if you use “Is Not Null”, then Access would be smart enough to use the Index).
Any thoughts on this?
