Microsoft SQL Server Microsoft SQL Server Administration for SAPAdministration for SAP

Performance Monitoring and Performance Monitoring and TuningTuning

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OverviewOverview

SQL Server ArchitectureSQL Server Architecture SQL Server with SAPSQL Server with SAP Performance Monitoring and TuningPerformance Monitoring and Tuning Administration and TroubleshootingAdministration and Troubleshooting Database Backup and RestoreDatabase Backup and Restore

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Database Performance Database Performance AnalysisAnalysis

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Database Performance Database Performance AnalysisAnalysis

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Database Performance Database Performance AnalysisAnalysis

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Cache and Cache and CPU CPU

TuningTuning Poor SQL statements?Poor SQL

statements?

Cache hit ratio> 95%?

Cache hit ratio> 95%?

2 * CPU idle> CPU busy?2 * CPU idle

> CPU busy?

OS paging?OS paging? All CPUs availablefor SQL Server?

All CPUs availablefor SQL Server?

Tune poorstatementsTune poorstatements

Increase server main

memory

Increase server main

memory

Add CPU(s)to server

Add CPU(s)to server

IncreaseCPUs for

SQL Server

IncreaseCPUs for

SQL Server+

Yes Yes

YesYes

No No

NoNo

?

Yes

No

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Database ConfigurationDatabase Configuration

affinity maskaffinity mask awe enabledawe enabled cost threshold for parallelismcost threshold for parallelism max degree of parallelismmax degree of parallelism fillfactorfillfactor index create memoryindex create memory lightweight poolinglightweight pooling Locks / open objects / connectionsLocks / open objects / connections Max/Min server memoryMax/Min server memory

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Database ConfigurationDatabase Configuration

max worker threadsmax worker threads min memory per querymin memory per query network packet size / protocolnetwork packet size / protocol priority boostpriority boost query governor cost limitquery governor cost limit query waitquery wait recovery intervalrecovery interval set working set sizeset working set size

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Server ParametersServer Parameters

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I/O I/O System System TuningTuning Slow RAID

identified?Slow RAIDidentified?

Avg. disk queuelength > 2 * phys.

Disks in RAID

Avg. disk queuelength > 2 * phys.

Disks in RAID

RAID 5 and mostly write

queue?

RAID 5 and mostly write

queue?

Check alllogical disks

with NT perfmon

Check alllogical disks

with NT perfmon

Switch to RAID 0+1Switch to RAID 0+1

Decreasemax async I/O

Decreasemax async I/O

Yes

No

No

?

No

Yes

Yes

Yes Peak I/O on I/O bus

< 133 MB/sec

Peak I/O on I/O bus

< 133 MB/sec

Add / speed up I/O bus

Peak I/O on RAID

< 40 MB/sec

Peak I/O on RAID

< 40 MB/sec

No

Yes

Add RAID + move disks

Yes

Check disk+ controller

No

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Server ConfigurationServer Configuration

Disk Disk layoutlayoutDisk Disk

layoutlayout

Parameter Parameter settingssettings

Parameter Parameter settingssettings

Hardware Hardware configurationconfiguration

Hardware Hardware configurationconfiguration

Main Main memorymemory

Main Main memorymemory

CPUCPUCPUCPU

DisksDisksDisksDisks

Poor database Poor database configurationconfiguration

Poor database Poor database configurationconfiguration

Poor configurationPoor configurationPoor configurationPoor configuration

Cache hit ratioCache hit ratio

SQL Server CPU utilization

DB error log

SQL Server CPU utilization

DB error log

High I/O times

High I/O times

Operating system paging

Operating system paging CPU

utilization CPU

utilization

Disk response

times

Disk response

times>95%

2 * idle > busy(SQL Server)

Select 1 row via prim. key> 10 ms 2 * idle > busy

(total)

Wait queueand low

transfer rate

Page in> 100 MB / h

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IsolationIsolationlevellevel

Scan type Scan type (Range, Table, (Range, Table,

Probe)Probe)

# of rows# of rowsin scanin scan

# of rows/page# of rows/page

Locking strategyLocking strategy(Table, Page, Row)(Table, Page, Row)

Operation type Operation type (scan, update)(scan, update)

Dynamic LockingDynamic Locking

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To lock a fine To lock a fine granule must granule must place intent locks place intent locks at higher granulesat higher granules

T1: IXT1: IX

T1: IXT1: IX

T1: XT1: X

T2: IST2: IS

T2: IST2: IS

T2: ST2: S

TableTable

PagePage PagePage PagePage

RowRow RowRow RowRow

Multi-Granular LockingMulti-Granular Locking

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ModeMode DescriptionDescription

SS Share - used for readingShare - used for reading

XX Exclusive - typically used for writingExclusive - typically used for writing

UU Update - used to evaluate prior to writingUpdate - used to evaluate prior to writing

ISIS Intent Share - share locking at finer levelIntent Share - share locking at finer level

IXIX Intent Exclusive - X locking at finer levelIntent Exclusive - X locking at finer level

SIXSIX Share Intent ExclusiveShare Intent Exclusive

Lock ModesLock Modes

Standard multi-granular Standard multi-granular lock modeslock modes

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Resource TypeResource Type Resource Specific DataResource Specific DataDatabase IDDatabase ID

HOW does SQL lock ?HOW does SQL lock ?

How do you identify a lock?How do you identify a lock? Lock “resource”Lock “resource”

Table “Authors”Table “Authors” Page 23Page 23 Row with Key = “23812”Row with Key = “23812”

Lock manager knows nothing Lock manager knows nothing about resource format; it simply about resource format; it simply does a “memcmp()”does a “memcmp()”

Lock resource format:Lock resource format:

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Example resource formats:Example resource formats: Table:Table:

Page:Page:

RowID:RowID:

Key:Key:

32565832565855 Object IDObject ID

2:3282:32866 File#: Page#File#: Page#

2:328:112:328:1199File# : Page# : File# : Page# : Slot on PageSlot on Page

325658:2:2341186325658:2:234118677 Object ID : IndexId : Object ID : IndexId : 6byte Hash6byte Hash

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55

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55ResourceResourcetypetype Database IDDatabase ID

Lock Resource FormatLock Resource Format

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New Lock HintsNew Lock Hints

Granularity HintsGranularity Hints ROWLOCK, PAGLOCK,TABLOCKROWLOCK, PAGLOCK,TABLOCK

ISOLEVEL HintsISOLEVEL Hints HOLDLOCK, NOLOCKHOLDLOCK, NOLOCK READCOMMITTED, READCOMMITTED,

REPEATABLEREAD, SERIALIZABLE, REPEATABLEREAD, SERIALIZABLE, READUNCOMMITTED [All New]READUNCOMMITTED [All New]

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New Lock HintsNew Lock Hints

READPASTREADPAST Useful for implementing work queuesUseful for implementing work queues

UPDLOCKUPDLOCK Select for updateSelect for update Deadlock due to select for updateDeadlock due to select for update Starving lock waitsStarving lock waits

LOCK_TIMEOUT(not a hint)LOCK_TIMEOUT(not a hint) Application response timeApplication response time

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Concurrency issue analysisConcurrency issue analysis

sp_who, sysprocessessp_who, sysprocesses sp_lockssp_locks SQL ProfilerSQL Profiler sp_indexoptionsp_indexoption DeadlockDeadlock DBCC inputbufferDBCC inputbuffer KillKill Lock waitsLock waits LatchesLatches

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Time

1. Work process

2. Work process

3. Work process

4. Work process

AcquiresMARA Lock

A long period of processing

CommitUpdate MARA

Working...WAITING!Update MARA

RequestsMARA Lock

AcquiresMARA Lock

Commit

Working...WAITING!Update MARA

RequestsMARA Lock

AcquiresMARA Lock

WAITING ...Update MARA

RequestsMARA Lock

MARAMARALocked

by:

WP 1 WP 2 WP 3

Lockwait SituationsLockwait Situations

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Monitoring LockwaitsMonitoring Lockwaits

R/3 Lock Monitor

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Process info from SQL Process info from SQL Enterprise ManagerEnterprise Manager

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Locks from SQL Enterprise Locks from SQL Enterprise ManagerManager

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Locks from SQL Enterprise Locks from SQL Enterprise ManagerManager

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ST04 Detailed AnalysisST04 Detailed Analysis

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Top Largest TablesTop Largest Tables

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Top Largest Updated TablesTop Largest Updated Tables

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ST05ST05

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Table AnalysisTable Analysis

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Table StatisticsTable Statistics

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SelectivitySelectivity

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DensityDensity

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DBCC ShowcontigDBCC Showcontig

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Performance HistoryPerformance History

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System TablesSystem Tables

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System ProceduresSystem Procedures

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Name Cache StatsName Cache Stats

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Stats on SPsStats on SPs

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Stats on SPsStats on SPs

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Stats on SPsStats on SPs

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Stats on SPsStats on SPs

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Stats on SPsStats on SPs

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Query issuesQuery issues

Unnecessary resultsUnnecessary results Select with no where clauseSelect with no where clause Select * instead of selecting few Select * instead of selecting few

columnscolumns Queries not qualified properlyQueries not qualified properly

Poorly written queriesPoorly written queries Missing indexMissing index Old statisticsOld statistics Incorrect optimizationIncorrect optimization

Index Tuning WizardIndex Tuning Wizard

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Choosing indexChoosing index

Space utilized by indexSpace utilized by index Index maintenance overheadIndex maintenance overhead To cluster or notTo cluster or not

Bookmark lookupBookmark lookup Range scan(OLTP Vs OLAP)Range scan(OLTP Vs OLAP)

Index columnsIndex columns Short & with high selectivityShort & with high selectivity Often used in many statementsOften used in many statements CoveredCovered Multi index queryMulti index query

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Monitoring Query executionMonitoring Query execution

Analyze query execution planAnalyze query execution plan Analyze the right plan - connection Analyze the right plan - connection

settingssettings

spid, blocked, waittype, cpu spid, blocked, waittype, cpu physical_io, memusage, open_tran physical_io, memusage, open_tran from sysprocessesfrom sysprocesses

Execution plan, read, write, duration Execution plan, read, write, duration in SQL Profilerin SQL Profiler

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Monitoring Query executionMonitoring Query execution

Stats I/oStats I/o Stats timeStats time Write your own traceWrite your own trace

Expected time / thresholdExpected time / threshold

WorktableWorktable Scan Vs SeekScan Vs Seek

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Query executionQuery execution

Query HintsQuery Hints Join, Index, Lock, ProcessingJoin, Index, Lock, Processing

Distributed query executionDistributed query execution TOP / SET ROWCOUNTTOP / SET ROWCOUNT FASTFIRSTROWFASTFIRSTROW IN / OR and subqueryIN / OR and subquery Selecting with aliasSelecting with alias

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Using stored proceduresUsing stored procedures

Cached execution planCached execution plan Recompiled when stats changesRecompiled when stats changes Warning: Wrong Parameter to stored Warning: Wrong Parameter to stored

procproc Binding parameter by positionBinding parameter by position Set nocountSet nocount sp_executesqlsp_executesql Auto-parameterization in SQL7Auto-parameterization in SQL7 sp_recompilesp_recompile

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Table statisticsTable statistics

Auto update statsAuto update stats Rowmodctr and StatVersionRowmodctr and StatVersion Fullscan and samplingFullscan and sampling

Auto column statsAuto column stats Explicit update statsExplicit update stats Explicit column statsExplicit column stats sp_autostatssp_autostats Queue / log tableQueue / log table sp_recompilesp_recompile

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Tuning Expensive SQL Tuning Expensive SQL StatementsStatementsPoor

statementPoor

statement

DDICinfo

DDICinfo

SQLExplain

SQLExplain

Whereused listWhere

used list

Is there asuitableindex?

Is there asuitableindex?

GoodOptimizerdecision?

GoodOptimizerdecision?

Inefficientcoding?

Inefficientcoding?

UpdatestatisticsUpdate

statistics

Re-codeRe-code

Yes

Yes

Yes

No

Index statistics

up to date?

Index statistics

up to date?

No

No

Re-codeor

change index

Re-codeor

change index

Yes

Statistics page

Statistics page

Autoupdatestats on?

Autoupdatestats on?

Switch onauto updstats

Switch onauto updstats

Yes

No

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LabLab

Improve the slow running reportImprove the slow running report Use ST05Use ST05 Stats on SPs(ST04)Stats on SPs(ST04) And other methodsAnd other methods

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SummarySummary

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