Difference between db_datareader and db_denydatawriter

Hi! I was just wondering that db_datareader and db_denydatawriter roles
look like doing the same function. I have read some threads on this
topic but they are not very clear. Can I have any comments on the
difference? I will be really obliged.
Thanks in advance
Kind regards,db_denydatawriter explicitly remove the ability for an id to modify any user
data within the database without respect to its ability to read. Read
privileges have to be managed elsewhere.
db_datareader on the other hand allows an id to read all user data within
the database without respect to its ability to modify the data. Data
modification privileges are managed elsewhere.
--Brian
(Please reply to the newsgroups only.)
<sajid_yusuf@.yahoo.com> wrote in message
news:1126004382.797483.258770@.g14g2000cwa.googlegroups.com...
> Hi! I was just wondering that db_datareader and db_denydatawriter roles
> look like doing the same function. I have read some threads on this
> topic but they are not very clear. Can I have any comments on the
> difference? I will be really obliged.
> Thanks in advance
> Kind regards,
>|||db_datareader allows reading data
db_denydatawriter explicitly denies updates, deletes.
User permissions are cumulative with deny taking precedence.
Explicitly denying permissions will prevent the user from
gaining permissions based on their membership in a group or
role (other than sysadmin which can't be denied anything) or
other explicit grants.
Some people put users in both roles to ensure that they can
only read data.
-Sue
On 6 Sep 2005 03:59:42 -0700, sajid_yusuf@.yahoo.com wrote:

>Hi! I was just wondering that db_datareader and db_denydatawriter roles
>look like doing the same function. I have read some threads on this
>topic but they are not very clear. Can I have any comments on the
>difference? I will be really obliged.
>Thanks in advance
>Kind regards,

Determining Proper Maxdop, Threshold and Worker Threads.

Hey guys - I am wondering if anyone can suggest some good literature on determining the proper Maxdop, Parallel Threshold, and # of worker threads to run.

We were in the MS Lab out in San Jose last week benchmarking our app against SQL 2k and SQL 2k5, and it seems that CXPackets were killing us in 2k5 (running against 4 dc opterons). Turning off Maxdop helped, but we have a pretty wide range of queries in our application - stuff ranging from a couple of milliseconds to an occasional 10k ms. I would like to use maxdop, but I am wondering how to approach finding the ideal threshold (other than just benchmarking it to death).

Also, same kind of question on worker threads - is there a methodology for finding the right setting for my environment, or is it pin the tail on the donkey?

Our app typically runs against 16 or 32 way boxes with tons of memory.

Hi,

There is a rule of thumb concerning the worker threads in the BOL of SQL Server 2005.
In SQL Server 2005 this is 'self tuning' by default.

I don't know of any 'wonder' formulas to determine the other settings (except benchmarking it to death) :-)
If I do find something I'll let you know.

Kr