Sql Server Index Tips

Question

I read the last two days about indexes and how to optimize the database.

Despite the fact that I have a clear understanding of the indexes, I still do not know how to practically optimize my database.

Could you suggest any tutorial or technique for optimizing the database.

Please be specific as I read many theories, but no specific instructions so far

thank

Answer 1

"aint" , . , , . , - !

: http://blogs.msdn.com/b/bartd/archive/2007/07/19/are-you-using-sql-s-missing-index-dmvs.aspx

, :

--based on http://stackoverflow.com/questions/1540192/searching-for-table-index-scans
--this query will show cahced query plans that "SCAN", change comments for other things

;WITH XMLNAMESPACES(DEFAULT N'http://schemas.microsoft.com/sqlserver/2004/07/showplan')
, CachedPlans AS
(SELECT
     RelOp.op.value(N'../../@NodeId', N'int') AS ParentOperationID
         ,RelOp.op.value(N'@NodeId', N'int') AS OperationID
         ,RelOp.op.value(N'@PhysicalOp', N'varchar(50)') AS PhysicalOperator
         ,RelOp.op.value(N'@LogicalOp', N'varchar(50)') AS LogicalOperator
         ,RelOp.op.value(N'@EstimatedTotalSubtreeCost ', N'float') AS EstimatedCost
         ,RelOp.op.value(N'@EstimateIO', N'float') AS EstimatedIO
         ,RelOp.op.value(N'@EstimateCPU', N'float') AS EstimatedCPU
         ,RelOp.op.value(N'@EstimateRows', N'float') AS EstimatedRows
         ,cp.plan_handle AS PlanHandle
         ,qp.query_plan AS QueryPlan
         ,st.TEXT AS QueryText
         ,cp.cacheobjtype AS CacheObjectType
         ,cp.objtype AS ObjectType
         ,cp.usecounts AS UseCounts
     FROM sys.dm_exec_cached_plans                            cp
         CROSS APPLY sys.dm_exec_sql_text(cp.plan_handle)     st
         CROSS APPLY sys.dm_exec_query_plan(cp.plan_handle)   qp
         CROSS APPLY qp.query_plan.nodes(N'//RelOp')          RelOp (op)
)
SELECT
    PlanHandle
        ,ParentOperationID
        ,OperationID
        ,PhysicalOperator
        ,LogicalOperator
        ,UseCounts
        ,CacheObjectType
        ,ObjectType
        ,EstimatedCost
        ,EstimatedIO
        ,EstimatedCPU
        ,EstimatedRows
        ,QueryText
    FROM CachedPlans
    WHERE CacheObjectType = N'Compiled Plan'
        AND PhysicalOperator IN ('nothing will ever match this one!'
                                --,'Assert'                             
                                --,'Bitmap'
                                --,'Clustered Index Delete'
                                --,'Clustered Index Insert'
                                ,'Clustered Index Scan'
                                --,'Clustered Index Seek'
                                --,'Clustered Index Update'
                                --,'Compute Scalar'
                                --,'Concatenation'
                                --,'Constant Scan'
                                ,'Deleted Scan'
                                --,'Filter'
                                --,'Hash Match'
                                ,'Index Scan'
                                --,'Index Seek'
                                --,'Index Spool'
                                ,'Inserted Scan'
                                --,'Merge Join'
                                --,'Nested Loops'
                                --,'Parallelism'
                                ,'Parameter Table Scan'
                                --,'RID Lookup'
                                --,'Segment'
                                --,'Sequence Project'
                                --,'Sort'
                                --,'Stream Aggregate'
                                --,'Table Delete'
                                --,'Table Insert'
                                ,'Table Scan'
                                --,'Table Spool'
                                --,'Table Update'
                                --,'Table-valued function'
                                --,'Top'
                                )

:

SELECT TOP 50
    total_worker_time/execution_count AS Avg_CPU_Time
        ,execution_count
        ,total_elapsed_time/execution_count as AVG_Run_Time
        ,(SELECT
              SUBSTRING(text,statement_start_offset/2,(CASE
                                                           WHEN statement_end_offset = -1 THEN LEN(CONVERT(nvarchar(max), text)) * 2 
                                                           ELSE statement_end_offset 
                                                       END -statement_start_offset)/2
                       ) FROM sys.dm_exec_sql_text(sql_handle)
         ) AS query_text 
FROM sys.dm_exec_query_stats 
ORDER BY 3 DESC

Answer 2

:

• SQLServerPedia
• SQL MVP Gail Shaw
• SQL Server Grant Fritchey. . SQL Server , , .

Answer 3

SQL Server SQL Profiler. , - SQL Server Profiler , SQL Profiler SQL Server.

Answer 4

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: , varchar (Max) , "% text%". , .

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Remember that each index adds time to insert, update, or delete. Although I noticed that users tend to take more time to do these things than return the results of a selection, it needs to be kept in mind.