Performance SQL Server.pdf

8/19/2019 Performance SQL Server.pdf

1/81

Maximiliano Damian AccottoMVP en SQL Server

http://www.triggerdb.com

http://blog.maxiaccotto.com

http://www.triggerdb.com/http://blog.maxiaccotto.com/http://blog.maxiaccotto.com/http://www.triggerdb.com/


2/81


3/81

Best Practices:Optimize forreal-worldworkloads

Monitor/reviewperformanceregularly

Focus onspecific issues

Establish abaseline

Identifybottlenecks

Make onechange at a time

Measureperformance

Repeat(if desired)


4/81

System/OS

WindowsPerformance Monitor

Alerts (Performance-Based)

SQLServer

Activity Monitor

SQL Profiler / SQLTrace

Database EngineTuning Advisor

DynamicManagement Views

(DMVs)

Query-Level

Database EngineTuning Advisor

Query ExecutionPlans


5/81


6/81

Category Metric

Largest single database 70 TB

Largest table 20 TB

Biggest total data 1 application 88 PB

Highest database transactionsper second 1 db (from Perfmon)

130,000

Fastest I/O subsystem in

production (SQLIO 64k buffer)

18 GB/sec

Fastest “real time” cube 5 sec latency

data load for 1TB 30 minutes

Largest cube 12 TB


7/81

Company Profile• World’s largest publicly listed online gaming platform• 20 million registered customers in more than 25 core markets

>14,000 bets offered simultaneously on more than 90 sports~ 90 live events with videos every day – bwin world’s largestbroadcaster of live sports>70,000 payment transactions (PCI Level 1 and ISO 27001 certified)

per day

Business Requirements• Failure is not an option

• 100% transactional consistency, zero data loss• 99.998% availability...even after loss of a data center

• Performance critical• Must scale to handle every user and and give them a great experience

• Protect users privacy and financial information• Provide a secure PCI compliant environment for all customers


8/81

SQL Server Environment• 100+ SQL Server Instances

• 120+ TB of data

• 1,400+ Databases

• 1,600+ TB storage

• 450,000+ SQL Statements per second on a single server

• 500+ Billion database transactions per day

Core component in solutions designated for:

• Financial transactions

• Gaming environments

• Tracking user state throughout the system

Solutions primarily scale-up using commodity hardware


9/81

SQL Server Infrastructure• Almost 200 production SQL Server instances


10/81

Single High Transaction throughput system provides:

Mission critical to the business in terms of performance andavailability


11/81

Project DescriptionMaintains US Equities and Options trading data

Processing 10’s of billions of transactions per day Average over 1 million business transactions/sec into SQL Server Peak: 10 million/sec

Require last 7 years of online dataData is used to comply with government regulations

Requirements for “real-time” query and analysis Approximately 500 TB per year , totaling over 2PB of uncompressed data

Largest tables approaching 10TB (page compressed) in size

Early Adopter and upgrade to SQL Server 2014 in-order-to:Better manage data growthImprove query performanceReduce database maintenance time


12/81

Data at this scale require breaking things down into manageable units:

Separate data into different logical areas:• A database per subject area (17)• A database per subject area per year (last 7 years)

Table and Index Partitioning:• 255 partitions per database• 25,000 filegroups• Filegroup to partition alignment for easier management/less impact moving data• Filegroup backups

Taking advantage of compression:• Compression per partition• Backup compression


13/81

Hardware OperatingSystem

Sql Server DatabaseDesign

Application


14/81


15/81

Use Disk Alignment at 1024KB

Use GPT if MBR not large enoughFormat partitions at 64KB allocation unit size

One partition per LUN

Only use Dynamic Disks when there is a need tostripe LUNs using Windows striping (i.e. AnalysisServices workload)

Tools:

Diskpar.exe, DiskPart.exe and DmDiag.exeFormat.exe, fsutil.exe

Disk Manager


16/81

Here is a graph of performance improvement fromMicrosoft’s white paper:


17/81

Sector Alignment

Basic MBR Partition Example

Commands

Diskpart

Select disk 0

List partition


18/81

Sector Alignment

Basic MBR Partition Example

Sample Output


19/81

RAID-1 is OK for log files and datafiles but you can dobetter…

RAID-5 is a BIG NO! for anything except read-only or read-

mostly datafilesRAID-10 is your best bet (but most expensive)

NEVER put OLTP log files on RAID-5!

If you can afford it:

Stripe And Mirror Everything (SAME) – one HUGERAID-10

SSD is even better – consider for tempdb and/or log files

If adventurous, use RAW partitions (see BOL)


20/81

As much as you can get…

…and more!64-bit is great for memory-intensive workloads

If still on 32-bit, use AWE

Are you sharing the box? How much memoryneeds to be set aside? Set max/min servermemory as needed.

Observe where all this memory goes:

Data Cache vs. Procedure Cache vs. Lock Managervs. Other

Keep an eye for „ A significant part of sql serverprocess memory has been paged out” error in theerrorlog.


21/81

Min/max server memory – when needed.

Locked pages:32-bit – when using AWE

x64 Enterprise Edition – just grant „Lock Pages inMemory” privilege

X64 Standard Edition – must have hotfix and enableTF845 (see KB970070 for details)

Large Pages:ONLY dedicated 64-bit servers with more than 8GB orRAM!

Enabled with TF834 – see KB920093

Server sloooooooow to start – be warned!


22/81

CPU is rarely the real bottleneck – look for WHYwe are using so much CPU power!

Use affinity mask as needed:Splitting the CPUs between applications (or SQLinstances)

Moving SQL Server OFF the CPU that serves NICIRQs

With a really busy server:Increase max worker threads (but be careful – it’s notfor free!)Consider lightweight pooling (be SUPER careful – noSQLCLR and some other features – see KB319942and BOL).


23/81

Parallelism is good:Gives you query results faster But at a cost of using a lot more CPU resources

MAXDOP setting is your friend:On server level (sp_configure „max degree ofparallelims”)

On Resource Governor workload group

On a single query (OPTION (MAXDOP 1))

Often overlooked:sp_configure „cost threshold for parallelism” (default 5)


24/81

Data file layout matters…

Choose your Recovery Model carefully:Full – highest recoverability but lowest performance

Bulk-logged – middle ground

Simple – no log backups, bulk operations minimallylogged

Always leave ON: Auto create statistics

Auto update statistics

Always leave OFF:

Auto shrink


25/81


26/81

Optimizes processing times RebuildUses more CPU cores

ALTER INDEX ALL ON Person.Person

REBUILD WITH (MAXDOP= 4)


27/81

MaxDOP CPU ms Duration ms

1 7344 7399

2 9797 5997

4 15845 5451


28/81

Designing High Performance I/O systemsSQL Server’s View of I/O


29/81

High rate of allocations to any data files can result in scaling

issues due to contention on allocation structuresImpacts decision for number of data files per file group

Especially a consideration on servers with many CPU cores

PFS/GAM/SGAM are structures within data file which managefree space

Easily diagnosed by looking for contention on PAGELATCH_UPEither real time on sys.dm_exec_requests or tracked insys.dm_os_wait_stats

Resource description in form of DBID:FILEID:PAGEID

Can be cross referenced withsys.dm_os_buffer_descriptors to determine type of page


30/81

More data files does not necessarily equal better

performanceDetermined mainly by 1) hardware capacity & 2) access patterns

Number of data files may impact scalability of heavy write

workloads

Potential for contention on allocation structures (PFS/GAM/SGAM

– more on this later)

Mainly a concern for applications with high rate of page allocations

on servers with >= 8 CPU cores

Can be used to maximize # of spindles – Data files can be

used to “stripe” database across more physical spindles


31/81

Provides less flexibility with respect to mapping datafiles into differing storage configurations

Multiple files can be used as a mechanism to stripedata across more physical spindles and/or serviceprocessors (applies to many small/mid range arrays)

A single file prevents possible optimizations related tofile placement of certain objects (relatively uncommon)

Allocations heavy workloads (PFS contention) mayincur waits on allocation structures, which aremaintained per file.


32/81

The primary filegroup contains all systemobjectsThese CANNOT be moved to anotherfilegroup

If using file group based backup, you mustbackup PRIMARY as part of regular backups

If not, you cannot restore!Primary must be restored before other filegroups

Best Practice: Allocate at least on additional filegroup and setthis to the default.Do not place objects in Primary


33/81

Microsoft Confidential


34/81

Virtual LOG Files & PerformanceSQL Server’s View of I/O


35/81


36/81

TRACE FLAGsSQL Server’s View of I/O


37/81

DBCC TRACEONUse -1 to turn on trace flag globally

DBCC TRACEOFF

DBCC TRACESTATUS-T startup flag

Use –T# separated by semi-colon (;)


38/81


39/81

Trace flag 610 controls minimally logged inserts into indexed tables

Allows for high volume data loadingLess information is written to the transaction logTransaction log file size can be greatly reducedIntroduced in SQL Server 2008“Very fussy”Documented:

Data Loading Performance Guide white paperhttp://msdn.microsoft.com/en-us/library/dd425070(v=sql.100).aspx

http://msdn.microsoft.com/en-us/library/dd425070(v=sql.100).aspxhttp://msdn.microsoft.com/en-us/library/dd425070(v=sql.100).aspx


40/81

Trace flag 1224 disables lock escalation based on the number of locksMemory pressure can still trigger lock escalationDatabase engine will escalate row or page locks to table locks40% of memory available for lockingsp_configure ‘locks’Non-AWE memoryScope: Global | SessionDocumented: BOL


41/81

Forces all files to auto-grow at the sametime


42/81

Trace flag 1118 directs SQL Server to allocate fullextents to each tempdb objects (instead of mixedextents)Less contention on internal structures such asSGAM pages

Story has improved in subsequent releases of SQLServer


43/81


44/81

Local and global temporary tables (andindexes if created)

User-defined tables and indexes

Table variablesTables returned in table-valued functions

Note: This list, and the following lists, are not designed to be all inclusive.


45/81

Work tables for DBCC CHECKDB and DBCCCHECKTABLE.

Work tables for hash operations, such as joins andaggregations.

Work tables for processing static or keyset cursors.

Work tables for processing Service Broker objects.

Work files needed for many GROUP BY, ORDER BY,UNION, SORT, and SELECT DISTINCT operations.

Work files for sorts that result from creating or rebuilding

indexes (SORT_IN_TEMPDB).


46/81

The version store is a collection of pages used to storerow-level versioning of data.

There are two types of version stores:1. Common Version Store: Examples include:

Triggers.

Snapshot isolation or read-committed snapshotisolation (uses less TEMPDB than snapshotisolation).

MARS (when multiple active result sets are

used).2. Online-Index-Build Version Store:

Used for online index builds or rebuilds. EEedition only.


47/81

TEMPDB is dropped and recreated every time the SQLServer service is stopped and restarted.

When SQL Server is restarted, TEMPDB inherits many ofthe characteristics of model, and creates an MDF file of8MB and an LDF file of 1MB (default setting).

By default, autogrowth is set to grow by 10% withunrestricted growth.

Each SQL Server instance may have only one TEMPDB,although TEMPDB may have multiple physical files.


48/81

Many TEMPDB database options can’t be changed (e.g.Database Read-Only, Auto Close, Auto Shrink).

TEMPDB only uses the simple recovery model.

TEMPDB may not be backed up, restored, be mirrored,have database snapshots made of it, or have many

DBCC commands run against it.TEMPDB may not be dropped, detached, or attached.


49/81

TEMPDB logging works differently from regular logging.Operations are minimally logged, as redo information is notincluded, which reduces TEMPDB transaction log activity.

The log is truncated constantly during the automaticcheckpoint process, and should not grow significantly,

although it can grow with long-running transactions, or ifdisk I/O is bottlenecked.

If a TEMPDB log file grows wildly:Check for long-running transactions (and kill them if necessary).

Check for I/O bottlenecks (and fix them if possible).

Manually running a checkpoint can often temporally reduce awildly growing log file if bottle-necked disk I/O is the problem.


50/81

Generally, there are three major problems yourun into with TEMPDB:1. TEMPDB is experiencing an I/O bottleneck, hurting server

performance.

2. TEMPDB is experiencing contention on various global allocation

structures (metadata pages) as temporary objects are being created,populated, and dropped. E.G. Any space-changing operationacquires a latch on PFS, GAM or SGAM pages to update spaceallocation metadata. A large number of such operations can causeexcessive waits while latches are acquired, creating a bottleneck(hotspot), and hurting performance.

3. TEMPDB has run out of space.Ideally, you should be monitoring all these on aproactive basis to identify potential problems.


51/81

Use Performance Monitor to determine how busy the disk is whereyour TEMPDB MDF and LDF files are located.

LogicalDisk Object: Avg. Disk Sec/Read: The average time, inseconds, of a read of data from disk. Numbers below are a generalguide only and may not apply to your hardware configuration.

Less than 10 milliseconds (ms) = very good

Between 10-20 ms = okayBetween 20-50 ms = slow, needs attention

Greater than 50 ms = serious IO bottleneck

LogicalDisk Object: Avg. Disk Sec/Write: The average time, inseconds, of a write of data to the disk. See above guidelines.

LogicalDisk: %Disk Time: The percentage of elapsed time that theselected disk drive is busy servicing read or write requests. A generalguideline is that if this value > 50%, there is a potential I/O bottleneck.


52/81

Use these performance counters to monitor allocation/deallocationcontention in SQL Server:

Access Methods:Worktables Created/sec: The number of work tablescreated per second. Work tables are temporary objects and are used tostore results for query spool, LOB variables, and cursors. This numbershould generally be less than 200, but can vary based on your hardware.

Access Methods:Workfiles Created/sec: Number of work files createdper second. Work files are similar to work tables but are created byhashing operations. Used to store temporary results for hash and hashaggregates. High values may indicate contention potential. Create abaseline.

Temp Tables Creation Rate: The number of temporary tablescreated/sec. High values may indicate contention potential. Create a

baseline.Temp Tables For Destruction: The number of temporary tables orvariables waiting to be destroyed by the cleanup system thread. Shouldbe near zero, although spikes are common.


53/81

Minimize the use of TEMPDBEnhance temporary object reuse

Add more RAM to your server

Locate TEMPDB on its own array

Locate TEMPDB on a fast I/O subsystem

Leave Auto Create Statistics & Auto Update Statistics on

Pre-allocate TEMPDB space – everyone needs to do this

Don’t shrink TEMPDB if you don’t need to

Divide TEMPDB among multiple physical files

Avoid using Transparent Data Encryption (2008)


54/81


55/81

If latches are waiting to be acquired on TEMPDB pages forvarious connections, this may indicate allocation pagecontention.

Use this code to find out:

SELECT session_id, wait_duration_ms, resource_descriptionFROM sys.dm_os_waiting_tasks

WHERE wait_type like 'PAGE%LATCH_%' AND resource_description like

'2:%'

Allocation Page

Contention:

2:1:1 = PFS Page2:1:2 = GAM Page2:1:3: = SGAM Page


56/81


57/81

Installation & Configuration Best Practices for Performance Server Role. Server should be a member server of a Microsoft

Active Directory network, and dedicated only to SQL Server.Windows File, Print, and Domain Controller services should beleft for other machines.

System Architecture. Use 64-bit architecture server.

32-Bit Systems. Include de /PAE parameter inside the boot.inif ile on Windows Server 2003 on servers with more than 4GBRAM.

SQL Server Edition. Use the DEVELOPER edition ondevelopment and test servers. Use the ENTERPRISE edition on

QA and Production servers.

CPU Cache. Use servers with CPUs that has L3 memorycache.

Whitepapers. Look for Low-Latency best practicesconfigurations on server manufacturer’s websites.

BIOS. Disable CPU Hyper-Threading (or “Logical Processor”) atthe BIOS level. Use Intel’s Processor ID utility to verify it.

BIOS. Disable CPU Turbo Mode (or Turbo Boost Optimization).

BIOS. Disable CPU C-States (or C-3, C6, etc.).

BIOS. Disable CPU C1E.

BIOS. Change Power Management to Maximum Performance.

BIOS. Disable QPI Power Management.

BIOS. Change Power Profile to Maximum Performance.

BIOS. Change Power Regulator to High Performance Mode.

RAM Modules. Validate with the server’s manufacturer low-latency recommendations on CPU and memory SIMMscombinations, as well as memory SIMMs location on multiplememory channels per processor.

RAM per CPU Core. For OLTP systems, use 2GB-4GB RAM

per CPU Core.

RAM per CPU Socket in Fast Track v3 (Data Warehousing).

For 2-CPU Socket use minimum of 96 GB RAM. For 4-CPUSocket use minimum of 128 GB RAM. For 8-CPU Socket useminimum of 256 GB RAM.

Processor Scheduling. Be sure that in Computer properties,Performance Options, the Processor Scheduling parameter isconfigured for “Background Services”.

Network Interface Cards. Have, at least, two network interface

cards connected to two different networks in order to divideapplication load from administrative load.


58/81

Installation & Configuration Best Practices for Performance Network Interface Cards. Configure each network interface

adapter for “Maximize data throughput for network applications”.

Network Interface Cards. For OLAP systems (DataWarehouses and Cubes), Database Mirroring, Log Shipping,and Replication… evaluate using Jumbo Frames (9-Mbps) onall devices that interact with each other (switches, routers, andNICs).

Disk Volumes. Use Solid-State (SSD) disks or 15K disks.

Disk Volumes. Use RAID-10 (or RAID-1) arrays when possible.Use RAID-5 as last option. Never use RAID-0. RAID-5 is

excellent for reading, but not best for writ ing (specially bad inrandom write). On direct-attached systems (DAS), if you needto balance performance and space between solid-state disks(SSD) and 15K disks (SAS), one strategy is to have solid-statedisk at RAID-5 and 15k disks at RAID-10.

RAID Controller. In virtual disks, indicate cache configurationin Write Policy = Write-Through (instead of Write-Back). Theobjective is to acknowledge the operating system thecomplet ion of the transaction when is written to the storagesystem instead of the RAID controller’s cache. Otherwise, is a

consistency risk if the controller’s battery is not working andenergy goes down.

Fast Track v3 (DW) – Disks. For Windows operating system

and SQL Server binary f iles, use a 2-Disk Spindles RAID-1local disks array.

Disk Volumes. Assign separate virtual disks (ex. SAN LUNs)for SQL Server data, log, tempdb, backups.

Disk Host Bus Adapter (HBA). Insert the HBA adapter into thefastest PCI-E slot.

PCIe x4 v2.0 delivers up to 2GB/sec.

PCIe x4 v1.0 delivers up 1GB/sec.

PCIe x1 v2.0 delivers up to 500MB/sec.

PCIe x1 v1.0 delivers up to 250MB/sec.

Disk Host Bus Adapter (HBA). Configure the HBA’s QueueDepth parameter (in Windows Registry) with the value thatreports the best performance on SQLIO tests (x86 and x64only) or SQLIOSIM (x86, x64, and IA64).

Fast Track v3 (DW) – Disks. For data files (*.MDF, *.NDF) usemultiple SAN/DAS storage enclosures that have multiple RAID-10 groups each one with at least 4-spindles, but dedicate oneRAID-10 group on each storage enclosure for log files (*.LDF).In Fast Track v3 tempdb is mixed with user databases.

Disk Volumes. Have each operating system disk partitioned asone volume only. Don’t divide each disk into multiple logicalvolumes.


59/81

Installation & Configuration Best Practices for Performance Disk Volumes. Partition each disk volume with Starting Offset

of 1024K (1048576).

Disk Volumes. Do NOT use Windows NTFS File Compression.

Disk Volumes. Format disk volumes using NTFS. Do not useFAT or FAT32.

Disk Volumes. Use Windows Mount Point Volumes (folders)instead of drive letters in Failover Clusters.

Disk Volumes. Format each SQL Server disk volume (data,log, tempdb, backups) with Allocation Unit of 64KB, and do aquick format if volumes are SAN Logical Units (LUNs).

Disk Volumes. Ratio #1. Be sure that the division result of DiskPartition Offset (ex. 1024KB) ÷ RAID Controller Stripe Unit Size(ex. 64KB) = equals an integer value. NOTE: This specific ratiois critical to minimize disk misalignment.

Disk Volumes. Ratio #2. Be sure that the division result of RAID Controller Stripe Unit Size (ex. 64KB) ÷ Disk Partit ion Allocation Unit Size (ex. 64KB) = equals an integer value.

Fast Track v3 (DW) – Multi-path I/O (MPIO) to SAN. Installand Multi-Path I/O (MPIO), configure each disk volume to havemultiple MPIO paths defined with, at least, one Active path, andconsult SAN vendor prescribe documentations.

Disk Volumes. Assign a unique disc volume to the MS DTC log file.

Also, before installing a SQL Server Failover Cluster, create aseparate resource dedicated to MS DTC.

Windows Internal Services. Disable any Windows service notneeded for SQL Server.

Windows Page File. Be sure that Windows paging is configure to useeach operating system disk only. Do not include paging file on any of SQL Server disks.

Antivirus. The antivirus software should be configure to NOT scanSQL Server database, logs, tempdb, and backup folders (*.mdf, *.ldf,*.ndf, *.bak) .

SQL Server Engine Startup Flags for Fast Track v3 (Data

Warehousing). Start the SQL Server Engine with the -E and -T1117startup flags.

SQL Server Service Accounts. Assign a different Active Directoryservice account to each SQL Server service installed.

Service Account and Windows Special Rights. Assign the SQLServer service account the following Windows user right policies: 1)Lock pages in memory, and 2) Perform volume maintenance tasks.

Address Windows Extensions (AWE). If the SQL Server serviceaccount has the Lock pages in memory Windows user right, thenenable the SQL instance AWE memory opt ion. ( Note: AWE wasremoved from SQL Server 2012; use 64-bit! ).


60/81

Installation & Configuration Best Practices for Performance Instance Maximum Server Memory. If exist only one (1) SQL

Database Instance and no other SQL engines, then configurethe instance’s Maximum Server Memory option with a value of 85% the global physical memory available.

Tempdb Data Files. Be sure that the tempdb database has thesame amount of data files as CPU cores and with the samesize.

Startup Parameter T1118. Evaluate the use of trace flag T1118as a startup parameter for the RDBMS engine to minimizeallocation contention in tempdb.

Maximum Degree of Parallelism (MAXDOP). For OLTP

systems, configure the instance’s MAXDOP=1 or higher (up to8) depending on the number of physical CPU chips. For OLAPsystems, configure MAXDOP=0 (zero).

Maximum Worker Threads. Configure the instance’sMaximum Worker Threads = 0 (zero).

Boost SQL Server Priority. Configure the instance’s BoostSQL Server Priority=0 (zero).

Database Data and Log Default Locations. Configure theinstance database default locations for data and log files.

Backup Files Default Location. Configure the instance backuplocation.

Backup Compression. In SQL Server 2008, enable the

instance backup compression option.

Filegroups. Before creating any database object (tables,indexes, etc.), create a new default filegroup (NOT PRIMARY)for data.

Data and Log Files Initial Size. Pre-allocate data and log filessizes. This will helps to minimize disk block fragmentation andconsuming time increasing file size stopping process until i tends.

Fast Track v3 (DW) – Compression. For Fact Tables use

Page Compression. In the other hand, compression for Dimension tables should be considered on a case-by-casebasis.

Fast Track v3 (DW) – Index Defragmentation. Whendefragmenting indexes, use ALTER INDEX [index_name] on[schema_name].[table_name] REBUILD (WITH MAXDOP = 1,SORT_IN_TEMPDB = TRUE) to improve performance andavoid filegroup fragmentation. Do not use the ALTER INDEXREORGANIZE statement. To defrag indexes specially on FACTTABLES from data warehouses, include

DATA_COMPRESSION = PAGE.

Tools. Use the Microsoft SQL Server 2008 R2 Best Practices Analyzer (BPA) to determine if something was left or notconfigured vs. best practices.


61/81

Installation & Configuration Best Practices for Performance Tools. Use Microsoft NT Testing TCP Tool (NTttcp) to

determine networking actual throughput.

Tools. Use Microsoft SQLIO and Microsoft SQLIOSim to stresstest storage and validate communication errors.

Tools. Use CPUID CPUz to determine processor information,specially at which speed is currently running.

Tools. Use Intel Processor Identification to determine processor information, specially if Hyperthreading is running.


62/81


63/81

Object Counter Value Notes

Paging $Usage


64/81

Logical Disk Counter Storage Guy’s term Description

Disk Reads / Second

Disk Writes / Second

IOPS Measures the Number of I/O’s per second

Discuss with vendor sizing of spindles of different

type and rotational speeds

Impacted by disk head movement (i.e. short stroking

the disk will provide more I/O per second capacity)

Average Disk sec / read

Average Disk sec / write

Latency Measures disk latency. Numbers will vary, optimal

values for averages over time:

1 - 5 ms for Log (Ideally 1ms or better)

5 - 20 ms for Data (OLTP) (Ideally 10ms or

better)


65/81


Physical Disk Avg DiskReads/sec

< 8> 20 is poor,


66/81


:Access MethodsForwarded

Records/sec


67/81


68/81

• DON’T RUN SQL Profiler in the server.• Then what?

• Run SQL Profiler in your computer.

• Connect to the server.

• Indicate the events and columns wanted.

• Filter by the database to be evaluated.• Run the trace for 1 second, then stop it.

• Export the trace as script.

• Optimize the script.

• And then and only then, run the SQL Trace Script in the server.

• And to evaluate?• Use the fn_trace_gettable() function to query the content of the

SQL Trace file(s).

• You can use the SQL Trace file(s) with SQL Server – DatabaseEngine Tuning Advisor to evaluate for the creation of new indexes.


69/81


70/81

General event handlingGoal is to make available well-defined datain XML format from execution points in code

Baked into SQL Server codeLayers on top of Event Tracing for Windows

Used by• SQL Trace, Performance Monitor and SQL

Server Audit

• Windows Event Log or SQL Error Log

• As desired by users in admin or development

Introduced in SQL Server 2008


71/81

Superset of Extended EventsCan be used in conjunction

with Extended Events

Can be a consumer ortarget of Extended

Events

Kernel level facility


72/81


73/81

Built in set of objects in EXE or DLL (aka Module)SQL Server has three types of packages• Package0

• SQLServer

• SQLOSPackages one or more object types

Event Targets

Actions Types

Predicates Maps


74/81

Monitoring point of interest in code of amodule

Event firing implies:• Point of interest in code reached

• State information available at time event fired

Events defined statically in packageregistration

Versioned schema defines contentsSchema with well-defined data types

Event data always has columns in same order

Targets can pick columns to consume


75/81

Targets are event consumersTargets can

• Write to a file

• Aggregate event data

• Start a task/action that is related to anevent

Process data synchronously or

asynchronouslyEither file targets or In-memory targets


76/81

File Targets• Event File• ETW File

In-Memory Targets• Ring Buffer • Event Bucketing

• Event Pairing

• Synchronous Event Counting


77/81

Executed on top of events before event infostored in buffers (which may be later sent tostorage)

Currently used toGet additional data related to event

TSQL statement

User

TSQL process info

Generate a mini-dump

Defined in ADD/ALTER EVENT clause


78/81

Logical expression that gate event to firePred_Compare – operator for pair of values

Value Compare Value

Example: Severity < 16

Example: Error_Message = ‘Hello World!’

Pred_Source – generic data not usually inevent

Package.Pred_Source Compare ValueExample: SQLServer.user_name = ‘Chuck’

Example: SQLOs.CPU_ID = 0

Defined in ADD/ALTER EVENT clause


79/81


80/81

Real-time data capture

No performance penalty

Based on Event Tracing for Windows (ETW)Full programmability support


81/81

Packages

Events and Actions

Filters and PredicatesSessions

Targets

Documents

Performance SQL Server.pdf