Difference between the estimated size and size given by sp_spaceus

Hi,
The Books Online article "Estimating the Size of a Table" gives you the
method to estimate the size of a table. Using this method I estimated the
size for one table. However after populating that table with data, I used
sp_spaceused to find out the space used by this particular table, but to my
surprise I found big difference between the value given by method "Estimatin
g
the Size of a Table" and sp_spaceused stored procedure. I also passed
updateusage parameter as true. Can anybody throw some light on why such
difference is found between these values?
Regards,
VaibhavVaibhav
Try UPDATE STATISTICS and then run sp_spaceused.
"Vaibhav" <Vaibhav@.discussions.microsoft.com> wrote in message
news:310A97C9-498D-4C12-B92A-F8C53814F4FF@.microsoft.com...
> Hi,
> The Books Online article "Estimating the Size of a Table" gives you the
> method to estimate the size of a table. Using this method I estimated the
> size for one table. However after populating that table with data, I used
> sp_spaceused to find out the space used by this particular table, but to
my
> surprise I found big difference between the value given by method
"Estimating
> the Size of a Table" and sp_spaceused stored procedure. I also passed
> updateusage parameter as true. Can anybody throw some light on why such
> difference is found between these values?
> Regards,
> Vaibhav|||> The Books Online article "Estimating the Size of a Table" gives you the
> method to estimate the size of a table. Using this method I estimated the
> size for one table. However after populating that table with data, I used
> sp_spaceused to find out the space used by this particular table, but to
my
> surprise I found big difference between the value given by method
"Estimating
> the Size of a Table" and sp_spaceused stored procedure. I also passed
> updateusage parameter as true. Can anybody throw some light on why such
> difference is found between these values?
Have you counted the indexes? Do you have variable length data types?
What are actal numbers?
Dejan Sarka, SQL Server MVP
Associate Mentor
www.SolidQualityLearning.com|||Well, do you have any variable-length data (VARCHAR, VARBINARY, TEXT,
IMAGE)? How many of them are populated to the maximum capacity, how many
are NULL (or empty string), how many have valid data? What kind of indexes
do you have? What is the "big difference", 10%, 50%?
This is my signature. It is a general reminder.
Please post DDL, sample data and desired results.
See http://www.aspfaq.com/5006 for info.
"Vaibhav" <Vaibhav@.discussions.microsoft.com> wrote in message
news:310A97C9-498D-4C12-B92A-F8C53814F4FF@.microsoft.com...
> Hi,
> The Books Online article "Estimating the Size of a Table" gives you the
> method to estimate the size of a table. Using this method I estimated the
> size for one table. However after populating that table with data, I used
> sp_spaceused to find out the space used by this particular table, but to
my
> surprise I found big difference between the value given by method
"Estimating
> the Size of a Table" and sp_spaceused stored procedure. I also passed
> updateusage parameter as true. Can anybody throw some light on why such
> difference is found between these values?
> Regards,
> Vaibhavsql