In one my tables (not very big, just 700 MB) , the performance for some of the queries goes bad in few days. I did some analysis and found that one of the index on that table , its large i/o efficiency value keeps going down and becomes 0.4. when we do full reorg rebuild it becomes 1 and performance improves.
I want to know why the large io efficiency values goes down. there are around 1million DML operations on that table on daily basis.
sybase experts please throw some light as always you do.