DBCC SHOWCONTIG(MyTable1)
GO
DBCC SHOWCONTIG scanning 'MyTable1' table...
Table: 'MyTable1' (1556968673); index ID: 1, database ID: 16
TABLE level scan performed.
- Pages Scanned................................: 18986
- Extents Scanned..............................: 2443
- Extent Switches..............................: 9238
- Avg. Pages per Extent........................: 7.8
- Scan Density [Best Count:Actual Count].......: 25.70% [2374:9239]
- Logical Scan Fragmentation ..................: 44.58%
- Extent Scan Fragmentation ...................: 87.07%
- Avg. Bytes Free per Page.....................: 1658.7
- Avg. Page Density (full).....................: 79.51%
DBCC execution completed. If DBCC printed error messages,
contact your system administrator.
* There were 18,986 pages examined to create the report. Those pages existed within 2,443 extents
* While examining the pages for fragmentation, the server had to switch extent locations 9,238 times.
The Scan Density restates this by indicating the percentage of all pages within all extents were contiguous. In an ideal environment, the density displayed would be close to 100.
* The Logical Scan Fragmentation and Extent Scan Fragmentation are indications of how well the indexes are stored within the system when a clustered index is present (and should be ignored for tables that do not have a clustered index).
In both cases, a number close to 0 is preferable.
* There are an average of 1659 bytes free per page, or that each page is 79.51% utilized. The closer that number gets to 100, the faster the database is able to read in records, since more records exist on a single page. However, this must be balanced with the cost of writing to the table. Since a page split will occur if a write is required on a page that is full, the overhead can be tremendous.
After DBCC INDEXDEFRAG/DBREINDEX
DBCC SHOWCONTIG scanning 'MyTable1' table...
Table: 'MyTable1' (1556968673); index ID: 1, database ID: 16
TABLE level scan performed.
- Pages Scanned................................: 15492
- Extents Scanned..............................: 1945
- Extent Switches..............................: 2363
- Avg. Pages per Extent........................: 8.0
- Scan Density [Best Count:Actual Count].......: 81.94% [1937:2364]
- Logical Scan Fragmentation ..................: 15.43%
- Extent Scan Fragmentation ...................: 20.15%
- Avg. Bytes Free per Page.....................: 159.8
- Avg. Page Density (full).....................: 98.03%
DBCC execution completed. If DBCC printed error messages,
contact your system administrator.
