BUG: DBCC SHOW_CONTIG May Return Invalid Values

• Microsoft SQL Server version 6.5

SYMPTOMS

DBCC SHOW_CONTIG returns a negative value for "Avg. Page Density" and an "Avg. Bytes free per page" value that is greater than the page size. The values resemble the following:

TABLE level scan performed.

 - Pages Scanned................................: 1
 - Extent Switches..............................: 0
 - Avg. Pages per Extent........................: 1.0
 - Scan Density [Best Count:Actual Count].......: 100.00% [0:1]
 - Avg. Bytes free per page.....................: 4294967294.0
 - Avg. Page density (full).....................: -213255475.67%
 - Overflow Pages...............................: 0
 - Disconnected Overflow Pages..................: 0

DBCC execution completed. If DBCC printed error messages, see your System Administrator. 

CAUSE

When pages belonging to the relevant object contain more than 2,014 bytes of information, (excluding page header data), the results shown in the SYMPTOMS section of this article are produced. Because a page cannot contain more than 2,016 bytes, this problem only occurs if pages contain exactly 2,015 or 2,016 bytes of information.

STATUS

Microsoft has confirmed this to be a problem in SQL Server version 6.5.

MORE INFORMATION

This scenario may occur when there is no free space on the page, and it can be considered to indicate a value of 0 for free space on the page and a page density of 100 percent.

This problem can occur for multiple pages where the majority of the pages are full in this way. When the row length is variable, the likelihood of this being the case across multiple pages is very small but the problem may still occur.

Additional query words: minus

Keywords          : SSrvTran_SQL kbbug6.50 
Version           : winnt:6.5
Platform          : winnt 
Issue type        : kbbug 

Last Reviewed: March 17, 1999