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  • 改进SQL Server 性能

    我们先来看一个用户表上的索引碎片情况: 

    DBCC SHOWCONTIG scanning 'Lead' table...
    Table: 'Lead' (1422628111); index ID: 1, database ID: 90
    TABLE level scan performed.
    - Pages Scanned................................: 135008
    - Extents Scanned..............................: 17511
    - Extent Switches..............................: 109860
    - Avg. Pages per Extent........................: 7.7
    - Scan Density [Best Count:Actual Count].......: 15.36% [16876:109861]
    - Logical Scan Fragmentation ..................: 91.29%
    - Extent Scan Fragmentation ...................: 30.66%
    - Avg. Bytes Free per Page.....................: 3082.4
    - Avg. Page Density (full).....................: 61.92%
    DBCC SHOWCONTIG scanning 'Lead' table...
    Table: 'Lead' (1422628111); index ID: 1, database ID: 90
    TABLE level scan performed.
    - Pages Scanned................................: 117309
    - Extents Scanned..............................: 14847
    - Extent Switches..............................: 36638
    - Avg. Pages per Extent........................: 7.9
    - Scan Density [Best Count:Actual Count].......: 40.02% [14664:36639]
    - Logical Scan Fragmentation ..................: 31.94%
    - Extent Scan Fragmentation ...................: 17.39%
    - Avg. Bytes Free per Page.....................: 3385.8
    - Avg. Page Density (full).....................: 58.17%
    DBCC execution completed. If DBCC printed error messages, contact your system administrator.

    碎片很严重,会导致性能低下, 可以重建索引来改进性能, 脚本如下:

    use [AdvantureWorks]
    declare @table_id int
    set @table_id=object_id('Lead')

    dbcc showcontig(@table_id)

    dbcc dbreindex('SFNewOrg.dbo.Lead','',70)

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  • 原文地址:https://www.cnblogs.com/yuzg/p/10682233.html
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