Posted by Roy Harvey on 06/30/07 02:10

On Fri, 29 Jun 2007 18:53:15 -0700, Ed Murphy <emurphy42@socal.rr.com>
wrote:

>Roy Harvey wrote:
>
>> On Fri, 29 Jun 2007 07:28:03 -0700, teddysnips@hotmail.com wrote:
>>
>>> SELECT COUNT(*) AS NumRows FROM Answer
>>>
>>> It returned 1,919,456. However, if I click on the Answer table in
>>> Enterprise Manager and select Properties it tells me that there are
>>> 1,919,421 rows. I've tried doing a refresh but it didn't work.
>>
>> Those statistics are not always accurate. To fix them run
>>
>> DBCC UPDATEUSAGE(0) WITH COUNT_ROWS
>
>Is it COUNT(*) or EM - Properties that is sometimes inaccurate? Under
>what circumstances may it be inaccurate?

Enterprise Manager. EM gets the count from index information
maintained by the system. The overhead of keeping the numbers
absolutely accurate at all times would be prohibitive, so the row
count gets out of sync with reality at times. The same goes for space
allocation, which UPDATEUSAGE also fixes.

SELECT COUNT(*) will always be correct.

Roy Harvey
Beacon Falls, CT

[Back to original message]