Re: Optimizer problem?

Phil Tsao wrote:
>
> 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

If you use an index as discribed in other reply(s) it's OK.
BUT your first full table scan WILL be time-consumting because of the delayed block-ceanout, witch means to mark the emptied block as empty in the second access transaction. So assume to make a full-table scan after a large delete.  

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