Optimizer problem?

Hi,

I was wondering if any one has experienced the same problem. I have a loop to add 10,000 rows to a table one by one then another loop

to delete each row one by one. After doing so a few times, the "select count(*) from table" starts doing table scan ( and physical read)
every time. I thought the index (on primary key) was corrupted due to the massive insert & delete and rebuilt it. It did not help. The only way I can force using index is to use hint or the following:

    select count(*) from table where pkey > -9999;

Is there anything you know that causes this to happen? Thanks in advance.

--
Phil Tsao
philt_at_technologist.com