Microsoft SQL Server 2008 R2 Unleashed- P232 doc

Configuration Options With SQL Server 2008, many options may affect the performance of individual SQL state-ments or the overall performance of a SQL Server instance.. FIGURE 55.2 SQL S

What’s New in Configuring, Tuning, and Optimizing

SQL Server Options

There are a few new configuration options in SQL Server 2008 R2 These new

configura-tion opconfigura-tions are user instance oriented (for SQL Server 2008 Express only), for FileStream,

Compression, and are Access Check Cache options However, you must be warned that

there are options available that are not obsolete yet but have no effect (even if you set

them) We identify them in this chapter as they come up.

SQL Server 2000 had a total of 36 options With SQL Server 2005, the number of options

nearly doubled, with a total of 64 (basic and advanced) active options There are now 70

basic and advanced options in SQL Server 2008 R2 Not all are usable, and some apply

only to certain OS platforms (64-bit) or SQL Server editions Only 68 basic and advanced

options appear on 32-bit–based platforms.

NOTE

You can’t use Allow Updates, Open Objects, or the Set Working Set Size sp_configure

options They have become obsolete and have no effect in SQL Server 2008, even

though they are still listed The Web Assistant Procedures option doesn’t exist anymore

either In addition, Microsoft has announced that all the ft_crawlandft_notify

options (ft= File Text) will be deprecated.

This chapter discusses the configuration options as well as the Database Engine Tuning

Advisor (DTA) and some of the reports available via the Data Collection service within

SQL Server Management Studio’s (SSMS’s) management options Microsoft is improving in

these areas, with new tuning analysis, improved recommendation reports, and now data

collection reports that can give you an overall picture of how your SQL Server instance is

performing.

SQL Server Instance Architecture

Figure 55.1 illustrates the address space architecture of an instance of SQL Server 2008 R2.

When you fire up a SQL Server instance, two main areas are allocated: the code area and

memory pool area The code area is mostly static executable code of the SQL Server kernel;

SQL Server NET Library DLLs; Open Data Services code; the stack space; and a variable

code area that contains distributed query OLE DB providers, OLE automation objects, and

extended stored procedures as they are needed by user requests.

The memory pool area of SQL Server is the most dynamically changing part of an

instance Even now, the once-static system data structures and user connection structures

(connection context) are controlled by user requests and dynamically allocate structures as

they are needed Then, there are the primary SQL Server databases master,tempdb,msdb,

andmodel There is another system database called a resource database that is present in

each SQL Server instance This read-only database contains system objects that are

included with SQL Server System objects are physically persisted in the resource database,

SQL Server 2008

Memory/BufferPool

User Connection Structures System Data Structures

Plan Cache

Buffer Cache

Other

Servers

Web-Based

Clients

Windows Clients

Windows Clients

Windows Clients

Log Cache

Master DB Temp DB

MSDB Resource DB Model DB

FIGURE 55.1 The SQL Server 2008 R2 instance architecture.

but they logically appear in the sys schema of every database and provide the results to

system-level information such as server properties (SERVERPROPERTY) and object definitions

(OBJECT_DEFINITION) Of these system-wide databases, tempdbhas the most significance

for performance because it is the heart of all internal tables, indexing, sorting, grouping,

and other worktable activity for the entire SQL Server instance.

By default, SQL Server tries to keep the amount of virtual memory allocations on a

computer at 4MB to 10MB less than the physical memory available The rest of the

memory pool area is divided into procedure cache, data cache (buffer cache), and log

cache SQL Server actively adjusts these for optimal performance Previously, the system

administrator had to do all this manually Many of the configurable options directly relate

to optimizing this address space There is a caching framework that utilizes internal and

external clocks to determine how the caches are managed; it is explained in Chapter 39.

Configuration Options

With SQL Server 2008, many options may affect the performance of individual SQL

state-ments or the overall performance of a SQL Server instance There are instance-wide

config-uration options (set using the sp_configuresystem stored procedure or with the server

FIGURE 55.2 SQL Server 2008 Configuration Properties dialog from SSMS.

properties dialog within SSMS), database-level options (set with ALTER DATABASE), database

compatibility levels (using the sp_dbcmptlevelsystem stored procedure), batch-level

options (using the SETcommand for things such as SET ANSI_NULLS), and statement-level

options (such as table hints, query hints, and join hints) Always remember that a hint

overrides a SEToption, a SEToption overrides a database option, and a database option

overrides an instance-wide option.

For SQL Server 2008, this chapter discusses the instance-wide configurable options in two

distinct categories: basic options and advanced options The advanced options are a

super-set of the basic options As each option is discussed, this chapter notes whether it is

self-configuring A self-configuring option is an option that adjusts itself dynamically, according

to the needs of the system In most cases, this eliminates the need for setting the values

manually Sometimes you don’t want to rely on certain self-configuring values, depending

on how SQL Server is being used This chapter identifies self-configuring values.

As you can see in Figure 55.2, SQL Server provides configuration parameters that the

system administrator can set to maximize the performance of a system from the

proper-ties option within SSMS You can set these and other SQL Server configuration

parame-ters by using thesp_configuresystem stored procedure as well.

Now, the only questions that need to be answered are “What configuration options do I

need to set that aren’t already fine?” and “How do I set them?”

To answer the “what” question, you first need to determine for what purpose the

applica-tions are using SQL Server The answer must include understanding variables such as the

number of potential connections to support, resources available on the box, size of the

database, type of data accesses occurring, and workload being put on SQL Server When

you know all this, it is easy to determine the configuration option setting to adjust.

The following shows a generalization of the types of applications you might find in the

real world that would be implemented using SQL Server 2008 and the general behavior

they elicit:

Online transaction processing (OLTP)—Mix of reads, writes, updates, and deletes.

Large number of concurrent users.

Data warehouse—Incremental loads (deltas), aggregation/transformation

process-ing, then primarily read-only Medium number of users.

Online analytical processing (OLAP)—Big loads, then primarily read-only.

Medium to large number of simultaneous users.

Mixed server—Mix of reads, writes, updates, deletes, big loads, and big extracts.

Large number of users.

This is not a complete list, just a generalized list Because these configuration options are

set at the SQL Server level, it is important to know the combined behavior of all

applica-tion processing For each SQL Server configuraapplica-tion opapplica-tion discussed in this chapter, we

recommend an appropriate setting, based on these generalized application processing

behavior types.

Now let’s answer the “How do I set them?” question The next few sections describe all

the types of configuration options available on SQL Server 2008 These sections show how

to set these configuration options using both SSMS and the sp_configuresystem stored

procedure The rule is that you can certainly set a configuration option using SSMS, but

you should keep an sp_configureversion of that setting change as a backup in case you

need to rebuild the entire server configuration from scratch In addition, keeping an

sp_configureversion around in a file provides a great audit trail of what you did and

why If you simply execute sp_configurewithout parameters, you are given a list of

options that can be addressed When you have just installed a SQL Server instance, you

can see only the basic configuration options.

SQL Server 2008 has 16 basic configuration options available:

exec sp_configure

go

name minimum maximum config_value run_value

- -

-allow updates 0 1 0 0

backup compression default 0 1 0 0

clr enabled 0 1 0 0

cross db ownership chaining 0 1 0 0

default language 0 9999 0 0

filestream access level 0 2 0 0

max text repl size (B) -1 2147483647 65536 65536

nested triggers 0 1 1 1

remote access 0 1 1 1

remote admin connections 0 1 0 0

remote login timeout (s) 0 2147483647 20 20

remote proc trans 0 1 0 0

remote query timeout (s) 0 2147483647 600 600

server trigger recursion 0 1 1 1

show advanced options 0 1 0 0

user options 0 32767 0 0

By default, all SQL Server users have permission to run the sp_configuresystem stored

procedure, but only users who have sysadminandserveradminfixed server roles (such as

sa) can actually set the value of a parameter.

The proper syntax of the sp_configurecommand is as follows:

exec sp_configure [parameter_name [, parameter_value ]]

In this syntax, parameter_nameis the name of the configuration parameter you want to

set, andparameter_valueis the value for the parameter Both of these parameters are

optional Parameters set bysp_configuretake effect at the server level.

Following is a brief explanation of the output of the sp_configurecommand As you can

see, the output consists of five columns:

Name —This is the name of the configurable option.

Minimum —This is the minimum legal value allowed for this parameter Passing an

illegal value causes SQL Server to return an error.

Maximum —This is the maximum legal value allowed for this parameter Passing an

illegal value causes SQL Server to return an error.

Config_value —This column reflects the values that will take effect the next time

SQL Server is started If you change static parameters, the new values are listed under

this column.

Run_value —This column reflects the values that SQL Server is currently using If

you change any dynamic parameters, the new values are listed in this column At

the time of SQL Server startup, config_valuefor all the parameters is copied into

run_value Immediately after restart, both columns (run_valueandconfig_value)

should display the same values, corresponding to each parameter.

If you specify a parameter name, SQL Server returns the current configuration value for

that particular parameter, as in this example:

exec sp_configure ‘clr enabled’

go

name minimum maximum config_value run_value

- -

-clr enabled 0 1 0 0

There are many more than 16 basic configuration options In fact, there are 70 configura-tion opconfigura-tions in total They consist of the original 16 basic opconfigura-tions plus 54 advanced options (including two for 64-bit processing) To see a complete list of all options, you turn on the show advanced optionconfiguration option with the value 1 In addition, when using sp_configureto change a setting, you use the RECONFIGURE WITH OVERRIDEstatement to make the change take effect immediately You can also choose to use just the RECONFIGUREstatement Depending on the configuration option, it may take effect immediately, or it may not take effect until the server has been restarted The following commands set the show advanced optionsconfiguration option and then retrieve the complete list of all configuration options: exec sp_configure ‘Show Advanced Options’, 1 /* Advanced config options */ go RECONFIGURE WITH OVERRIDE /* to have it take effect immediately */ go sp_configure go name minimum maximum config_value run_value - -

-access check cache bucket count 0 65536 0 0

access check cache quota 0 2147483647 0 0

Ad Hoc Distributed Queries 0 1 0 0

affinity I/O mask -2147483648 2147483647 0 0

affinity mask -2147483648 2147483647 0 0

affinity64 I/O mask -2147483648 2147483647 0 0

affinity64 mask -2147483648 2147483647 0 0

Agent XPs 0 1 1 1

allow updates 0 1 0 0

awe enabled 0 1 0 0

backup compression default 0 1 0 0

blocked process threshold (s) 0 86400 0 0 c2 audit mode 0 1 0 0

clr enabled 0 1 0 0

common criteria compliance enabled 0 1 0 0

cost threshold for parallelism 0 32767 5 5

cross db ownership chaining 0 1 0 0

cursor threshold -1 2147483647 -1 -1

Database Mail XPs 0 1 0 0

default full-text language 0 2147483647 1033 1033

default language 0 9999 0 0

default trace enabled 0 1 1 1

disallow results from triggers 0 1 0 0

EKM provider enabled 0 1 0 0

filestream access level 0 2 0 0

fill factor (%) 0 100 0 0

ft crawl bandwidth (max) 0 32767 100 100

ft crawl bandwidth (min) 0 32767 0 0

ft notify bandwidth (max) 0 32767 100 100

ft notify bandwidth (min) 0 32767 0 0

index create memory (KB) 704 2147483647 0 0

in-doubt xact resolution 0 2 0 0

lightweight pooling 0 1 0 0

locks 5000 2147483647 0 0

max degree of parallelism 0 1024 0 0

max full-text crawl range 0 256 4 4

max server memory (MB) 16 2147483647 2147483647 2147483647 max text repl size (B) -1 2147483647 65536 65536

max worker threads 128 32767 0 0

media retention 0 365 0 0

min memory per query (KB) 512 2147483647 1024 1024

min server memory (MB) 0 2147483647 0 0

nested triggers 0 1 1 1

network packet size (B) 512 32767 4096 4096

Ole Automation Procedures 0 1 0 0

open objects 0 2147483647 0 0

optimize for ad hoc workloads 0 1 0 0

PH timeout (s) 1 3600 60 60

precompute rank 0 1 0 0

priority boost 0 1 0 0

query governor cost limit 0 2147483647 0 0

query wait (s) -1 2147483647 -1 -1

recovery interval (min) 0 32767 0 0

remote access 0 1 1 1

remote admin connections 0 1 0 0

remote login timeout (s) 0 2147483647 20 20

remote proc trans 0 1 0 0

remote query timeout (s) 0 2147483647 600 600

Replication XPs 0 1 0 0

scan for startup procs 0 1 0 0

server trigger recursion 0 1 1 1

set working set size 0 1 0 0

show advanced options 0 1 1 1

SMO and DMO XPs 0 1 1 1

SQL Mail XPs 0 1 0 0

transform noise words 0 1 0 0

two digit year cutoff 1753 9999 2049 2049

user connections 0 32767 0 0

user options 0 32767 0 0

xp_cmdshell 0 1 0 0

Microsoft suggests that only very experienced SQL Server administrators change these

advanced configuration options In general, this is good advice because most of these

options are set to where you might want them as you start out As you learn more about

your application and the other things happening in your SQL Server instance, you will

change them more and more You have been warned!

Earlier SQL Server 2008 R2 documentation also listed a configuration option,

enable_force_flush, that wasn’t present in the November Community Technology

Preview (CTP) for R2 We’re not sure whether we will see it very soon.

With SQL Server 2008, you can see all the configuration options and their current settings

via system views The sys.configurationsview shows the option, a description, and the

current value in use for each configuration option The following example shows what

you might expect to see if you query the sys.configurationsview:

SELECT convert(varchar(10),value_in_use) AS ‘Value in Use’,

substring (name,1,30) AS ‘Configuration Option’,

substring (description,1,30) AS ‘Description’

FROM sys.configurations

ORDER BY 2

Go

Value in Use Configuration Option Description

-

-0 access check cache bucket coun Default hash bucket count for

0 access check cache quota Default quota for the access c

0 Ad Hoc Distributed Queries Enable or disable Ad Hoc Distr

0 affinity I/O mask affinity I/O mask

0 affinity mask affinity mask

0 affinity64 I/O mask affinity64 I/O mask

0 affinity64 mask affinity64 mask

1 Agent XPs Enable or disable Agent XPs

0 allow updates Allow updates to system tables

0 awe enabled AWE enabled in the server

0 backup compression default Enable compression of backups

0 blocked process threshold (s) Blocked process reporting thre

0 c2 audit mode c2 audit mode

0 clr enabled CLR user code execution enable

0 common criteria compliance ena Common Criteria compliance mod

5 cost threshold for parallelism cost threshold for parallelism

0 cross db ownership chaining Allow cross db ownership chain

-1 cursor threshold cursor threshold

0 Database Mail XPs Enable or disable Database Mai

1033 default full-text language default full-text language

0 default language default language

1 default trace enabled Enable or disable the default

0 disallow results from triggers Disallow returning results fro

0 EKM provider enabled Enable or disable EKM provider

0 filestream access level Sets the FILESTREAM access lev

0 fill factor (%) Default fill factor percentage

100 ft crawl bandwidth (max) Max number of full-text crawl

0 ft crawl bandwidth (min) Number of reserved full-text c

100 ft notify bandwidth (max) Max number of full-text notifi

0 ft notify bandwidth (min) Number of reserved full-text n

0 index create memory (KB) Memory for index create sorts

0 in-doubt xact resolution Recovery policy for DTC transa

0 lightweight pooling User mode scheduler uses light

0 locks Number of locks for all users

0 max degree of parallelism maximum degree of parallelism

4 max full-text crawl range Maximum crawl ranges allowed

2147483647 max server memory (MB) Maximum size of server memory

65536 max text repl size (B) Maximum size of a text field i

0 max worker threads Maximum worker threads

0 media retention Tape retention period in days

1024 min memory per query (KB) minimum memory per query (kByt

0 min server memory (MB) Minimum size of server memory

1 nested triggers Allow triggers to be invoked w

4096 network packet size (B) Network packet size

0 Ole Automation Procedures Enable or disable Ole Automati

0 open objects Number of open database object

0 optimize for ad hoc workloads When this option is set, plan

60 PH timeout (s) DB connection timeout for full

0 precompute rank Use precomputed rank for

full-0 priority boost Priority boost

0 query governor cost limit Maximum estimated cost allowed

-1 query wait (s) maximum time to wait for query

0 recovery interval (min) Maximum recovery interval in m

1 remote access Allow remote access

0 remote admin connections Dedicated Admin Connections ar

20 remote login timeout (s) remote login timeout

0 remote proc trans Create DTC transaction for rem

600 remote query timeout (s) remote query timeout

0 Replication XPs Enable or disable Replication

0 scan for startup procs scan for startup stored proced

1 server trigger recursion Allow recursion for server lev

0 set working set size set working set size

1 show advanced options show advanced options

1 SMO and DMO XPs Enable or disable SMO and DMO

0 SQL Mail XPs Enable or disable SQL Mail XPs

0 transform noise words Transform noise words for full

2049 two digit year cutoff two digit year cutoff

0 user connections Number of user connections all

0 user options user options

0 xp_cmdshell Enable or disable command shel

Dynamically changing configuration options are also updated so that their values are

visible through the system views.

Fixing an Incorrect Option Setting

Setting a parameter value too high might cause SQL Server to crash during startup For

example, if you set the value of the memory option to a value that is higher than the

physical memory on the machine, SQL Server does not start In this case, you start SQL

Server with the-foption, which causes SQL Server to start with the default parameter

values (the same values used by the Setup program when you installed SQL Server) After

SQL Server is running, you can change the incorrect value to the correct one and restart

SQL Server without the-foption.

Setting Configuration Options with SSMS

As mentioned previously, you can set SQL Server configuration options by using SSMS.

You simply invoke SSMS from the Microsoft SQL Server program group and right-click the

Serverfolder In Figure 55.2, you can see the SQL Server Properties pane, the different

server categories of options that are available (General, Processors, Memory, and so on),

and the selected option category properties that can be adjusted Keep in mind that some

of these options are not configuration options that correspond tosp_configure(for

example, the Root Directory or Platform properties of the General Server Instance

proper-ties options) However, as you will see, Microsoft has done a nice job of organizing and

presenting the option information In addition, you can look at either the configured

option value or the running values If you are manipulating these, they may not be the

same.

Not all 70 configuration options can be set from SMSS; only about half of them can It’s

therefore best to get to know the sp_configuresystem stored procedure Remember that

you must have sysadminandserveradminfixed server roles to make changes.

All the sp_configuresettings and options used in this chapter are included in a SQL script

namedSQLConfigOptions.sqlthat you can find on the CD for this book.

Obsolete Configuration Options

Many configuration options available in SQL Server 7.0 or SQL Server 2000 have become

obsolete or do not function any longer Some options, such as time slice, were

intro-duced in SQL Server 7.0 and then immediately became obsolete.

The following configuration options are obsolete in SQL Server 2008:

. Allow Update(remains listed but cannot be set)