DBCC SHOWCONTIG and Extent Switches

All,
I executed the following statement at my production server.
DBCC SHOWCONTIG WITH TABLERESULTS, ALL_INDEXES
which provided me the following resultset. Besides "AveragePageDensity" and
"LogicalFragmentation", I paid special attention to "Extent Swithces" which
is quite high.
Is there any performance gain if I reduce th Extent Switces? How can I
lessen the value of Extent Switches.
TIA
Kay
ObjectName ObjectId IndexName
IndexId
Level Pages Rows MinimumRecordSize MaximumRecordSize AverageRecordSize
ForwardedRecords Extents ExtentSwitches AverageFreeBytes AveragePageDensity
ScanDensity BestCount ActualCount LogicalFragmentation ExtentFragmentation
package 1845581613 PK_package 1 0 527 224182 15 15 15 0 72 77 864.322
89.321 84.615 66 78 1.898 18.056
package 1845581613 package80 5 0 306 224182 9 9 9 0 42 41 37.169
99.541 92.857 39 42 1.307 16.667
package 1845581613 package69 6 0 388 224182 9 12 11.98 0 51 50 18.417
99.772 96.078 49 51 0.258 13.725
package_description 1450240717 PK_package_description 1 0 3226 169022
44 434 138.77 0 413 412 720.535 91.098 97.821 404 413 0.217 10.412
package_description 1450240717 package_description73 2 0 296 169022 12
12 12 0 42 43 101.716 98.743 84.091 37 44 1.351 14.286
package_description 1450240717 idx_package_name 3 0 1904 169022 8 370
77.871 0 249 636 1005.600 87.576 37.363 238 637 11.922 22.088
package_description 1450240717 idx_package_state 4 0 341 169022 12 12
12 0 47 129 1156.680 85.709 33.077 43 130 14.663 21.277
package_description 1450240717 idx_package_hours 5 0 396 169022 16 16
16 0 54 79 413.181 94.895 62.500 50 80 5.303 22.222
package_description 1450240717 idx_package_cost 6 0 411 169022 16 16
16 0 56 115 693.576 91.431 44.828 52 116 8.273 17.857
package_description 1450240717 idx_package_available 7 0 298 169022 12
12 12 0 42 48 155.369 98.080 77.551 38 49 2.349 16.667
package_description 1450240717 tpackage_description 255 0 114597
340665 32 8094 2076.854 0 14336 14335 1916.141 76.326 99.923 14325 14336
99.999 17.153
pass_quiz_options 1877581727 0 0 1 2 35 45 40 0 1 0 8012.000 1.013
100.000 1 1 0.000 0.000Kay
http://www.sql-server-performance.com/dt_dbcc_showcontig.asp
"Kay" <CallDBA@.hotmail.com> wrote in message
news:OmnmxiiBGHA.3840@.TK2MSFTNGP15.phx.gbl...
> All,
>
> I executed the following statement at my production server.
> DBCC SHOWCONTIG WITH TABLERESULTS, ALL_INDEXES
> which provided me the following resultset. Besides "AveragePageDensity"
> and "LogicalFragmentation", I paid special attention to "Extent Swithces"
> which is quite high.
>
> Is there any performance gain if I reduce th Extent Switces? How can I
> lessen the value of Extent Switches.
>
> TIA
>
> Kay
>
> ObjectName ObjectId IndexName
> IndexId
> Level Pages Rows MinimumRecordSize MaximumRecordSize AverageRecordSize
> ForwardedRecords Extents ExtentSwitches AverageFreeBytes
> AveragePageDensity ScanDensity BestCount ActualCount LogicalFragmentation
> ExtentFragmentation
> package 1845581613 PK_package 1 0 527 224182 15 15 15 0 72 77 864.322
> 89.321 84.615 66 78 1.898 18.056
> package 1845581613 package80 5 0 306 224182 9 9 9 0 42 41 37.169
> 99.541 92.857 39 42 1.307 16.667
> package 1845581613 package69 6 0 388 224182 9 12 11.98 0 51 50 18.417
> 99.772 96.078 49 51 0.258 13.725
> package_description 1450240717 PK_package_description 1 0 3226 169022
> 44 434 138.77 0 413 412 720.535 91.098 97.821 404 413 0.217 10.412
> package_description 1450240717 package_description73 2 0 296 169022
> 12 12 12 0 42 43 101.716 98.743 84.091 37 44 1.351 14.286
> package_description 1450240717 idx_package_name 3 0 1904 169022 8 370
> 77.871 0 249 636 1005.600 87.576 37.363 238 637 11.922 22.088
> package_description 1450240717 idx_package_state 4 0 341 169022 12 12
> 12 0 47 129 1156.680 85.709 33.077 43 130 14.663 21.277
> package_description 1450240717 idx_package_hours 5 0 396 169022 16 16
> 16 0 54 79 413.181 94.895 62.500 50 80 5.303 22.222
> package_description 1450240717 idx_package_cost 6 0 411 169022 16 16
> 16 0 56 115 693.576 91.431 44.828 52 116 8.273 17.857
> package_description 1450240717 idx_package_available 7 0 298 169022
> 12 12 12 0 42 48 155.369 98.080 77.551 38 49 2.349 16.667
> package_description 1450240717 tpackage_description 255 0 114597
> 340665 32 8094 2076.854 0 14336 14335 1916.141 76.326 99.923 14325 14336
> 99.999 17.153
> pass_quiz_options 1877581727 0 0 1 2 35 45 40 0 1 0 8012.000 1.013
> 100.000 1 1 0.000 0.000
>
>
>|||Based on the result set provided and viewing the clustered index, your extent
switches are fine. Extent switches is the number of times the DBCC statement
moved off an extent while it was scanning the pages in the extent. You would
expect an extent switch to happen after the whole extent had been scanned.
The most useful line of output would be the ScanDensity BestCount
ActualCount. This is your measure of fragmentation. The best count is the
ideal number of extents, where as the actual count is the actual number of
extents use to hold the data pages.
I noticed the AveragePageDensity is around 89.321, which indicates a
fillfactor of 90 set for the clustered index. In a clustered index, since the
leaf level contains the data, you can use FILLFACTOR to control how much
space to leave in the table itself. By reserving free space, you can avoid
splitting pages to make room for a new entry. NOTE that FILLFACTOR is not
maintained; it only indicates how much space is reserved with the existing
data at the time the index is built. If you need to, you can use the DBCC
DBREINDEX command to rebuild the index and reestablish the original
FILLFACTOR specified, also reducing fragmentation.
"Kay" wrote:
> All,
>
> I executed the following statement at my production server.
> DBCC SHOWCONTIG WITH TABLERESULTS, ALL_INDEXES
> which provided me the following resultset. Besides "AveragePageDensity" and
> "LogicalFragmentation", I paid special attention to "Extent Swithces" which
> is quite high.
>
> Is there any performance gain if I reduce th Extent Switces? How can I
> lessen the value of Extent Switches.
>
> TIA
>
> Kay
>
> ObjectName ObjectId IndexName
> IndexId
> Level Pages Rows MinimumRecordSize MaximumRecordSize AverageRecordSize
> ForwardedRecords Extents ExtentSwitches AverageFreeBytes AveragePageDensity
> ScanDensity BestCount ActualCount LogicalFragmentation ExtentFragmentation
> package 1845581613 PK_package 1 0 527 224182 15 15 15 0 72 77 864.322
> 89.321 84.615 66 78 1.898 18.056
> package 1845581613 package80 5 0 306 224182 9 9 9 0 42 41 37.169
> 99.541 92.857 39 42 1.307 16.667
> package 1845581613 package69 6 0 388 224182 9 12 11.98 0 51 50 18.417
> 99.772 96.078 49 51 0.258 13.725
> package_description 1450240717 PK_package_description 1 0 3226 169022
> 44 434 138.77 0 413 412 720.535 91.098 97.821 404 413 0.217 10.412
> package_description 1450240717 package_description73 2 0 296 169022 12
> 12 12 0 42 43 101.716 98.743 84.091 37 44 1.351 14.286
> package_description 1450240717 idx_package_name 3 0 1904 169022 8 370
> 77.871 0 249 636 1005.600 87.576 37.363 238 637 11.922 22.088
> package_description 1450240717 idx_package_state 4 0 341 169022 12 12
> 12 0 47 129 1156.680 85.709 33.077 43 130 14.663 21.277
> package_description 1450240717 idx_package_hours 5 0 396 169022 16 16
> 16 0 54 79 413.181 94.895 62.500 50 80 5.303 22.222
> package_description 1450240717 idx_package_cost 6 0 411 169022 16 16
> 16 0 56 115 693.576 91.431 44.828 52 116 8.273 17.857
> package_description 1450240717 idx_package_available 7 0 298 169022 12
> 12 12 0 42 48 155.369 98.080 77.551 38 49 2.349 16.667
> package_description 1450240717 tpackage_description 255 0 114597
> 340665 32 8094 2076.854 0 14336 14335 1916.141 76.326 99.923 14325 14336
> 99.999 17.153
> pass_quiz_options 1877581727 0 0 1 2 35 45 40 0 1 0 8012.000 1.013
> 100.000 1 1 0.000 0.000
>
>
>
>