Andy Hassall wrote:
> On 8 Dec 2006 13:43:33 -0800, "prateek" <hkprateek_at_gmail.com> wrote:
>
>> I am curious to know why this query:
>>
>> "select count(*) from far_employee sample block (1);"
>>
>> returns zero at times and some other times returns a non zero number.
>> Table: far_employee is populated with more than 400K records.
>
> The blocks sampled probably contained no rows, i.e. they are below the HWM for
> the table, but not currently populated.
You may be correct ... but it seems unlikely. If sampling is a
percentage ... then 1% should sample 1% of the blocks. I have a table
I ran some tests on with 1056 blocks created with CREATE TABLE AS ...
and SAMPLE BLOCK(1) consistently returns zero. Seems unlikely with a
CTAS just as it seems unlikely that 10 blocks (1%) are unpopulated.
I could get in their with DBMS_ROWID and find out for sure but it is
Friday ... and I'm heading for a glass of scotch.
--
Daniel A. Morgan
University of Washington
damorgan_at_x.washington.edu
(replace x with u to respond)
Puget Sound Oracle Users Group
www.psoug.org
Received on Fri Dec 08 2006 - 16:58:28 CST
