managing sql server performance atlantamdf august 11, 2003 by larry ansley

Managing SQL ServerPerformance

AtlantaMDF

August 11, 2003

By Larry Ansley

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http://www.dilbert.com/comics/dilbert/archive/images/dilbert2003081524509.gif

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Performance Maximization PlanIn Only 4 Easy Steps

• Denormalize

• Index Everything

• Use Full-Text Searches Liberally

• Get a Bigger, More Powerful System

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Performance AreasHardware

• Memory

• CPU

• Storage

• Network

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Performance AreasOperating System

• Configuration

• Version Upgrades

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Performance AreasOperating System

• Configuration

• File Management


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Performance AreasSQL Server

• Configuration & Options

• File Management


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Performance AreasDatabases

• Configuration & Options

• Tables

• Indexes

• File Management

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Performance AreasStored Procedures

• Logic

• Best Practices

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Performance Killers

1. Poor indexing

2. Inaccurate statistics

3. Excessive fragmentation

4. Non-reusable execution plans

5. Frequent recompilation

6. Excessive blocking and deadlocks

7. Poor query design

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Performance Killers

8. Poor database design

9. Improper cursor use

10. Ineffective connection pooling

11. Improper database log configuration

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Taming The Performance Killers

• Planning– ER Diagrams– Data Modeling– Capacity Requirements– Procedure Case Analysis

• Follow Best Practices in Development

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Taming The Performance Killers

• Good Record Keeping– Logs– Baselines– Audits

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Performance BaselinesBenefits

• Allows us to analyze resource bottlenecks

• Allows us to troubleshoot by comparing system utilization patterns with pre-established baselines

• Allows us to make accurate estimates in capacity planning and scheduling hardware upgrades

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Performance BaselinesBenefits

• Aids us in identifying low utilization periods, when we can execute administrative activities

• Helps us distinguish between performance perception and reality

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Performance BaselinesBaseline Tools

• System Monitor (Key Resource Counters)– CPU – % Processor Time (85%) – CPU – Processor Queue Length (2) – Memory – Available Bytes (4 MB)– Memory – Pages / Sec (20) – Memory – Buffer Cache Hit Ratio ( 90%)

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• System Monitor (Key Resource Counters)– Disk – % Disk Time (90%) – Disk – Avg. Disk Queue Length (number of

spindles + 2) – Network – % Net Utilization (30% for

Ethernet) – SQL Server – User Connections

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• SQL Profiler– Record Traces for Major Processes– Duration, CPU, Reads, Writes

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Performance Audit

• System Monitor• Hardware• Operating System• SQL Server Configuration• Database Settings• Indexes• Application and Transact-SQL

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Performance AuditSystem Monitor

• Processor: % Processor Time– Recurring period exceeding 80% indicate CPU

bottlenecks

• System: Processor Queue Length– Recurring periods exceeding 2 per CPU

indicate CPU bottlenecks– Consider Maximum Worker Threads setting

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• Memory: Pages / Sec– Average around 0 over 24 hours– Average over 20 indicates memory bottleneck

• Memory: Available Bytes– Should be greater than 5 MB– Dedicated SQL Servers attempt to maintain 4-10 MB free– Less than 5 MB indicates a memory bottleneck

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• SQL Server Buffer: Buffer Cache Hit Ratio– For OLTP application, should exceed 90%,

ideally around 99%– OLAP (Analysis Services) application work

well with lower ratios

• SQL Server General: User Connections– If this exceeds 255, Maximum Worker Threads

setting should be increased to remain greater than user connections, thus avoiding thread sharing.

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• Physical Disk: % Disk Time– Should run less than 55%– Recurring periods (10 minutes or more)

exceeding 55% indicate I/O bottlenecks

• Physical Disk: Avg. Disk Queue Length– Should run less than 2 per spindle– Recurring periods exceeding 2 indicate I/O

bottlenecks

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Performance AuditHardware

• Number of CPUs• CPU MHz• CPU L2 Cache Size• Physical Ram Amount• Total Amount of Available Drive Space on

Server• Total Number of Physical Drives in Each

Array

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• Hardware vs. Software Raid

• RAID Level of Each Array Used

• Disk Fragmentation Level

• Location of Operating System

• Location of SQL Server Executables

• Location of Swap File

• Location of tempdb Database

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• Location of System Databases

• Location of User Databases

• Location of Log Files

• Number of Disk Controllers in Server

• Type of Disk Controllers in Server

• Size of Cache in Disk Controllers In Server

• Is Write Cache in Disk Controller On or Off

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• Speed of Disk Drives• How Many Network Cards Are in Server• Are the Network Cards Hard-Coded for

Speed/Duplex• Are the Network Cards Attached to a

Switch• Are All the Hardware Drivers Up-to-Date• Is This Physical Server Dedicated to SQL

Server

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Performance AuditOperating System

• Are the Disk Partitions NTFS 5.0

• Is “NTFS Data File Encryption and Compression” Turned Off

• Is the Server Updated With the Latest Service Pack

• Does the Server Have the Most Current, Microsoft-Certified Hardware Drivers

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• Is the Windows 2000 Server Configured as a Stand-Alone Server

• Are the Physical Files on the Server Overly Fragmented

• Is the “Application Response” Setting Set to “Optimize Performance” for “Background Services”

• Has Security Auditing Been Turned On

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• How Large Is the Server’s PAGEFILE.SYS swap file

• Have Unnecessary Services Been Turned Off

• Have All Unnecessary Network Protocols Been Turned Off

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Performance AuditSQL Server Configuration

Settings Advanced Restart Default Current

Affinity mask Yes Yes 0

Awe enabled Yes Yes 0

Cost threshold for parallelism

Yes No 5

Cursor threshold

Yes No -1

Fill factor (%) Yes Yes 0

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Index create memory (KB)

Yes No 0

Lightweight pooling

Yes Yes 0

Locks Yes Yes 0

Max degree of parallelism

Yes No 0

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Max server memory (MB)

Yes No 2,147,483,647

Max text repl size (B)

No No 65536

Max worker threads

Yes Yes 255

Min memory per query (KB)

Yes No 1024

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Min server memory (MB)

Yes No 0

Nested triggers No No 1

Network packet size (B)

Yes No 4096

Open objects Yes Yes 0

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Priority boost Yes Yes 0

Query governor cost limit

Yes No 0

Query wait (s) Yes No -1

Recovery interval (min)

Yes No 0

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Scan for startup procs

Yes No 0

Set working set size

Yes Yes 0

User connections

Yes No 0

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Performance AuditDatabase Configuration Settings

Database Setting Default Current

Auto_close Off

Auto_create_statistics On

Auto_update_statistics On

Auto_shrink Off

Read_only Off

Torn_page_detection On in 2000

Off in 7.0

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Performance AuditDatabase Configuration Settings

Database Setting Default Current

Compatibility level 80 for 2000

70 for 7.0

Database auto grow On

Transaction log auto grow

On

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Performance AuditIndexes

• Have you run the Index Tuning Wizard recently

• Does every table in each database have a clustered index

• Are any of the columns in any table indexed more than once

• Are there any indexes that are not being used in queries

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Performance AuditIndexes

• Are the indexes too wide

• Do the tables that are joined have the appropriate indexes on the joined columns

• Are the indexes unique enough to be useful

• Are you taking advantage of covering indexes

• How often are indexes rebuilt

• What is your index fillfactor

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Performance AuditTransact-SQL

• Does the Transaction-SQL code return more data than needed

• Are cursors being used when they don’t need to be

• Are Union and Union Select properly used• Is Select Distinct being used properly• Is the Where clause Sargable• Are temp tables used when they aren’t

needed

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• Are hints being properly used in queries

• Are view unnecessarily being used

• Are stored procedures being used whenever possible

• Inside stored procedures, is Set NoCount On being used

• Do any of your stored procedures start with sp_

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• Are all stored procedures owned by DBO and referred to in the form of databaseowner.objectname

• Are you using constraints or triggers for referential integrity

• Are transactions being kept as short as possible

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Performance AuditApplications

• Is the application using stored procedures, strings of T-SQL code, or using an object model, like ADO, to communicate with SQL Server

• What method is the application using to communicate with SQL Server: DB-Lib, DAO, RDO, ADO, .Net

• Is the application using ODBC or OLE DB to communicate with SQL Server

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• Is the application taking advantage of connection pooling

• Is the application properly opening, reusing, and closing connections

• Is the T-SQL code being sent to SQL Server optimized for SQL Server, or is it generic SQL

• Does the application return unnecessary data

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• Is the application taking advantage of connection pooling

• Is the application properly opening, reusing, and closing connections

• Is the T-SQL code being sent to SQL Server optimized for SQL Server, or is it generic SQL

• Does the application return unnecessary data

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• Does the application keep transaction open when the user is modifying data

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Monitoring & Measuring Tools

• Enterprise Manager

• Query Analyzer

• System Monitor

• SQL Profiler

• 3rd Party

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Monitoring & Measuring ToolsEnterprise Manager

• Management / Current Activity– Process Info (sp_who2)– Locks / Process ID (sp_lock)– Locks / Object (sp_lock)

• Management / SQL Server Logs

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Monitoring & Measuring ToolsQuery Analyzer

• sp_who / sp_who2• sp_lock• sp_spaceused• sp_monitor• Showplan_Text• Showplan_All• Set Statistics IO• Set Statistics Time• Set Statistics Profile

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• DBCC Commands– DBCC UserOptions– DBCC Show_Statistics– DBCC ShowContig– DBCC IndexDefrag– DBCC PerfMon– DBCC TraceOn / DBCC TraceOff

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• Built-in Functions– @@CPU_Busy

– @@IO_Busy

– @@Packet_Errors

– @@Connections

– @@Total_Read

– @@Total_Write

– @@Total_Errors

– @@TranCount

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• System Tables– Master.dbo.sysprocesses– Master.dbo.syslockinfo– Master.dbo.sysperfinfo– Master.dbo.syscacheobjects– dbo.sysobjects– dbo.sysindexes

• _WA_Sys_AcctNo_2216C367, hind_1400444113_1A_6A_7A

– dbo.sysindexkeys– dbo.syscolumns– dbo.sysdepends

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SQL Profiler & Query Analyzer Highest Execution Count

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SQL Profiler & Query Analyzer Longest Single Duration

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SQL Profiler & Query Analyzer Longest Aggregate Duration

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SQL Profiler & Query Analyzer Recompiles

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Suggested ReadingPrinted Books

• Inside SQL Server 2000– Kalen Delaney (Microsoft Press, 2001)

• SQL Server Query Performance Tuning Distilled– Sajal Dam (Curlingstone, 2003)

• SQL Server 2000 for Experienced DBAs– Brian Knight (Osborne, 2003)

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Suggested ReadingE-Books

• Microsoft SQL Server Books On Line

• Start to Finish Guide to SQL Server Performance Monitoring– Brian Kelly (NetImpress, 2002)

• Hands-On SQL Server 2000 Troubleshooting: Locking and Blocking– Kalen Delaney (NetImpress, 2003)

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Suggested ReadingPeriodicals

• SQL Server Magazine (Penton Media)

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Suggested ReadingWeb Sites & Web Articles

• http://www.sql-server-performance.com– Brad McGehee – How to Perform a SQL Server

Performance Audit; and many others– Randy Dyess – An Introduction to SQL Server

Query Tuning; and many others– Joe Chang – SQL Server Quantitative

Performance Analysis

• http://www.sqlservercentral.com– Brian Knight

http://www.sql-server-performance.com/

http://www.sqlservercentral.com/

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• http://www.sqlmag.com– Kalen Delaney – Recompiling Riddles; and

many more– Neil Pike – What is the precedence of the SET

commands, database options, session options, etc.

• http://www.sqlteam.com• http://www.algonet.se/~sommar/index.html

– Erland Sommarskog MBP – aba_lockinfo

http://www.sqlmag.com/

http://www.sqlteam.com/

http://www.algonet.se/~sommar/index.html

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• http://www.msdn.microsoft.com

• http://support.microsoft.com/default.aspx?scid=fh;EN-US;KBHOWTO

• http://www.msdn.microsoft.com/library/default.asp?url=/nhp/Default.asp?contentid=28000409

• http://www.microsoft.com/sql/

http://www.msdn.microsoft.com/

http://support.microsoft.com/default.aspx?scid=fh;EN-US;KBHOWTO

http://support.microsoft.com/default.aspx?scid=fh;EN-US;KBHOWTO

http://www.msdn.microsoft.com/library/default.asp?url=/nhp/Default.asp?contentid=28000409



http://www.microsoft.com/sql/

managing sql server performance atlantamdf august 11, 2003 by larry ansley

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