March 31, 2004 at 9:42 am
What is the page size in SQL Server 2000?
I just ran the dbcc showcontig (RC_Tracks) and gave me these results
DBCC SHOWCONTIG scanning 'RC_Tracks' table...
Table: 'RC_Tracks' (375060472); index ID: 1, database ID: 8
TABLE level scan performed.
- Pages Scanned................................: 3
- Extents Scanned..............................: 3
- Extent Switches..............................: 2
- Avg. Pages per Extent........................: 1.0
- Scan Density [Best Count:Actual Count].......: 33.33% [1:3]
- Logical Scan Fragmentation ..................: 33.33%
- Extent Scan Fragmentation ...................: 66.67%
- Avg. Bytes Free per Page.....................: 2716.7
- Avg. Page Density (full).....................: 66.44%
DBCC execution completed. If DBCC printed error messages, contact your system administrator.
Can somebody explain me what are the following lines:
- Extents Scanned
- Extent Switches
- Scan Density [Best Count:Actual Count]
thanks in advance
Kindest Regards,
@puy Inc
March 31, 2004 at 11:11 am
The page size is 8 KB.
An extent is 8 contiguous pages, meaning it's 64 KB.
3 pages across 3 extents means you have pages scatted across 3 separate extents. SQL Server, when tracing these pages, had to switch from one extent to another 2 times (the minimum required for 3 extents). Scan density gives you the ratio of the best case scenario where all pages are contiguous versus what it is actually. Given 3 pages, all should fit on 1 extent. However, real world is the 3 pages are scattered across 3 separate extents. Therefore, the scan density is 1:3 or 33.33%.
K. Brian Kelley
@kbriankelley
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