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Agenda

Key Concepts About PerformanceFactors Affecting SQL PerformanceSQL Performance Tuning MethodologiesSQL Performance Tuning Tools

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Key Concepts About Performance

What is performance issue?CPU utilization high, memory usage high, disk latency high?Query response is slow?Query timeout/failure?

Response TimeThroughputBaselineBottleneck

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Factors Affecting SQL Performance

Application Designdata caching, data archivingtransactional/reporting access isolation, read/write access isolationtransaction management (concurrency control)

Database Design missing indexes, excessive indexesinappropriate column types, over-normalization, table partitioning

Query Design poor queries (OR/LIKE/EXISTS operators, indexed column conversion)inappropriate use of views/triggers/cursors

SQL Server and OSimproperly configured (PAE/AWE, max server memory, MAXDOP)Improperly maintained (inaccurate statistics, index fragmentation)

Hardwareinsufficient resources (CPU, Memory, Disk, etc.)

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SQL Performance Tuning Methodologies

Is there resource bottleneck?CPU, Memory, Disk, etc.

What is happening in SQL Server?What has happened in SQL Server?Tuning slow queries

High CPU/IO queriesLow CPU/IO, high duration queries

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Is there resource bottleneck?

Windows Performance CountersCPU

Processor\%Processor TimeProcess(sqlservr)\% Processor Time

MemoryMemory\Available MbytesSQLServer:Buffer Manager\Lazy writes/secSQLServer:Buffer Manager\Page life expectancySQLServer:Buffer Manager\Page reads/sec

DiskPhysicalDisk\Avg. Disk sec/ReadPhysicalDisk\Avg. Disk sec/WritePhysicalDisk\% Idle Time

SQL Server Resource Wait StatisticsSQLServer:Wait Statistics

SQL Server system catalogssys.dm_os_wait_statssys.dm_os_waiting_tasks

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Analyzing what is happening

Point-in-time analysisWho is activeIs it running or waiting?What is it waiting for?

Analyzing active sessionsRunning, Runnable or Suspended

Using Management Studio Activity MonitorGraphical Reports

Using system catalogs sys.dm_exec_requestssys.dm_exec_sessionssys.dm_os_waiting_taskssys.sysprocesses, sp_who, sp_who2

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Analyzing what has happened

Cumulative analysisWhose duration has been long?Who has consumed the most resources?What has it been waiting for?

Analyzing top queries and top resource waitsHigh duration, CPU or IO

Using Management Studio Graphical Reports

Using system catalogs sys.dm_exec_query_statssys.dm_os_wait_statssys.dm_db_index_usage_stats

Using SQL Server Tracing

Tuning expensive queries

High CPU/IO queriesTuning the query itself: analyzing the execution planPossible solutions:

Optimizing index designUpdating index statisticsOptimizing T-SQL queriesOptimizing application logic design

High duration queriesIdentifying the waited resource

Most popular causes: blocking issue, Disk IO bottleneck, latch contention.http://technet.microsoft.com/library/Cc966413

Possible solutions:Optimizing transaction/application logic designOptimizing Disk IO systems

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SQL Performance Tuning Tools

SQL Server Management StudioActivity MonitorGraphical Reports

SQL Server Performance Dashboard Reports http://www.microsoft.com/en-us/download/details.aspx?id=29063

Query Execution PlanSystem Catalogs

TracingPssdiag/SqldiagSQLNexus

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Tracing

Data collection for SQL Server internal events Some of the events are performance relatedTracing introduces performance overhead

Two methods:SQL Profiler: GUI tool, more overheadServer Side: Using system stored procedures to define and execute server-side trace, less overhead

sp_trace_createsp_trace_setstatussys.traces

Tracing template

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Tracing - Events

TSQLSQL:BatchStarting, SQL:BatchCompletedSQL:StmtStarting, SQL:StmtCompleted

Stored ProceduresRPC:Starting, RPC:CompletedSP:Starting, SP:CompletedSP:StmtStarting, SP:StmtCompleted

PerformanceShowplan XMLShowplan XML Statistics Profile

Error and WarningsBlocked process report

LocksDeadlock graph

Pssdiag/Sqldiag

Collecting all the useful data togetherWindows performance LogsWindows event LogsSQL Server configuration informationSQL Server traceActive sessionsBlocking informationResoure wait statistics

Free download (Pssdiag/Sqldiag Manager)http://diagmanager.codeplex.com

SQLNexus

Loads and analyzes performance data collected by Pssdiag/Sqldiag

CPU utilizationResource wait statisticsBlockingsTop queries

Free downloadhttp://sqlnexus.codeplex.com

http://social.technet.microsoft.com/wiki/contents/articles/5957.sql-server-performance-survival-guide.aspx

SQL Server Performance Survival Guide