check whether reverse key index instead of traditional b-tree is useful, if the values are in sequential, unique or as you said not necessary primary key reversekey index will be more useful I suppose. thanks..subodh On 18 January 2011 02:09, <Joel.Patterson@xxxxxxxxxxx> wrote: > > I would like to verify this assumption. > > You have an index, not necessarily the primary key, (10g) and the columns > position is 1, or with some indexes 2, and is a DATE data type. > The data is inserted into the tables each day by “todays” DATE… yesterday, > today, tomorrow, and is deleted from the table by the oldest, oldest, > next_oldest etc. > It is a HEAP index (using a binary search by default). > > “The index always grows”. > > Lets start with a fresh rebuild: > > Then data is inserted into the index always on one side (the most > recent). Data is always deleted on the other side (the least recent). > > Even if all the records in each block where to be deleted, oracle would > never reuse the leaf node because data is always being inserted on the ‘most > recent’ side of the index. > > Eventually the ‘middle’ of the index, (the start of the binary search), > becomes the least recent entry… thus the index is always traversed from that > point to the most recent side. > The index has been skewed in that everything is to the most recent side of > the entry point. > > Coalescing does not help the DML. (even if it would help the size). > > Any comments on any of these points is appreciated, > > Thank you very much. > > Joel Patterson > Database Administrator > 904 727-2546 > > > -- ============================== DO NOT FORGET TO SMILE TODAY ==============================