Question about parallel operations of SQLServer

Our system will support about 200 concurrent users during work time. But
some heavy queries are executed in parallel sometimes. When this is
happening, the server is really stressed and even logon to the server will
take long time. We have tried our best to optimize these heavy queries and
we can not totally eliminate the parallel process. What should we do? should
we turn off the parallel option? How does your server configured?
Thanks for any response.
Lijunreduce the setting "max degree of parallelism" to something less than the
total number of processors on the machine.
Kevin Connell, MCDBA
----
The views expressed here are my own
and not of my employer.
----
"Lijun Zhang" <nospam@.nospam.nospam> wrote in message
news:#KXBHLKqDHA.3320@.tk2msftngp13.phx.gbl...
> Our system will support about 200 concurrent users during work time. But
> some heavy queries are executed in parallel sometimes. When this is
> happening, the server is really stressed and even logon to the server will
> take long time. We have tried our best to optimize these heavy queries and
> we can not totally eliminate the parallel process. What should we do?
should
> we turn off the parallel option? How does your server configured?
> Thanks for any response.
> Lijun
>|||Hi Lijun,
Thanks for your post. Generally, the bottleneck of the query performance
might be on many factors (mainly divided into four parts) such as the
Number and Type of Processor, Memory Size and Usage, Physical Disk I/O,
Multiple threads (Hardware and Operating System Limitations); Provider to
connect server, Network Communication Speed, Numbers of connection
(Connection Limitation); Execution Plan, Statistics, Index, Data Volume,
Returned result sets, locks/deadlocks, long-run transactions/store
procedure (SQL Server Specific Issues); Cursor Location, Coding consistent,
application designing issue (VB Specific Issues). Therefore, the
configuration on the server side is not the only thing we need to concern
for the performance of SQL Server.
In this case, how did the 200 concurrent users connect to SQL Server during
work time, using Query Analyzer or in Application?
You wrote "the server is really stressed and even logon to the server will
take long time. What do you mean by the "long time"? How many seconds do
you spend on query and logon at the worst situation?
What does the hardware configuration on our side? How many processors do
you have?
Did some jobs worked on the background inducing the server busy?
The above things that affect the query performance are all need to be
considered on your side. For detailed reference on how to perform the
configuration on the server side, please read the following article
seriously and perform some configurations which meet your needs. 319942 HOW
TO: Determine Proper SQL Server Configuration Settings
http://support.microsoft.com/?id=319942
For additional information regarding this issue please refer to the
following article on SQL Server Books Online.
Topic: "max degree of parallelism Option"
Topic: "Degree of Parallelism"
For how to troubleshoot SQL Server performance issues step-by-step, please
reference the following Microsoft technical article which accurately
determine the source of a performance issue.
224587.KB.EN-US INF: Troubleshooting Application Performance with SQL Server
http://support.microsoft.com/default.aspx?scid=KB;EN-US;224587
For detailed information on how to perform QUERY TUNING, please follow the
directions of the following article which specifies accurate
troubleshooting unexpectedly long-lasting queries and updates and provides
very effective method to deal with the poorly performing queries:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/optimsql/od
p_tun_1_536v.asp
Also, due to the complexity of this issue, it would be best to contact
Microsoft Product Support Services via telephone so that a dedicated
Support Professional can assist with your request. To obtain the phone
numbers for specific technology request please take a look at the web site
listed below.
http://support.microsoft.com/default.aspx?scid=fh;EN-US;PHONENUMBERS
Thanks for using MSDN newsgroup.
Regards,
Michael Shao
Microsoft Online Partner Support
Get Secure! - www.microsoft.com/security
This posting is provided "as is" with no warranties and confers no rights.|||Sorry if I sound silly
Can you make sure there are not too many "Select * INTO..." statements in your SQL these can also HOLD locks on system tables, that can make logging into sql server slow.