3
votes
1answer
62 views

Is support for Parallel Scalar UDF a reasonable feature request?

It is fairly well documented that scalar UDF's force an overall serial plan. Running functions in parallel Given a large number of rows coming into a point in the pipeline where a UDF must be ...
3
votes
2answers
173 views

Deadlock with simple queries in sql server 2008

I have an application that must delete and insert registries from a table, the table is storing the historic registries for an access control and is stored with the datetime for the check in the ...
3
votes
2answers
2k views

High CXPACKET and LATCH_EX waits

I am having some performance issues with a data processing system which I am working on. I have gathered wait stats from a one hour peroid which show a large amount of CXPACKET and LATCH_EX wait ...
0
votes
1answer
115 views

How is parallelism threshold (seconds) used if query CPU cost is actually unitless

How does the optimizer decide whether or not to use parallelism when the parallelism threshold is specified in seconds (on specific hardware, see below) but the estimated CPU costs are supposedly ...
1
vote
0answers
129 views

Why does removing a RID by creating a clustered index lose parallelism and slow down execution by 2X

If I remove a RID lookup by replacing 2 non-clustered indices (non unique) with 2 identical clustered indicies (non-unique) where there weren't any before, why does this query slow down by a factor ...
8
votes
2answers
3k views

Need to understand parallel query execution error

Today we experienced a degradation in performance on our production sql server. Durring the time this occurred we logged several "The query processor could not start the necessary thread resources ...
3
votes
0answers
210 views

Are the following statements concerning sys.dm_exec_requests true?

Parallel plans mean that cpu_time can be greater than total_elapsed time. Therefore, per-query wait time is not possible to determine accurately from DMVs on servers with more than one CPU thread. ...
3
votes
1answer
186 views

SQL Server parallelism issue

I am rather new to SQL Server administrations, I am running an SSIS that never ends... A) looking at the processes using SELECT r.*, t.text FROM sys.dm_exec_requests r CROSS APPLY ...
3
votes
2answers
798 views

Parallel Statistics Update

In SQL Server 2008 or later, is UPDATE STATISTICS WITH FULLSCAN a single threaded operation or it can use parallelism? How about update statistics with default sampling - can it use parallelism? I ...
1
vote
2answers
993 views

Is problem with parallelism more common today than before? And what issues can arise from paralellism?

This is a very general question so I don't give much specific information. I am more interested in parallelism and its possible drawbacks. Generally I am all for parallelism as something useful and ...
6
votes
6answers
5k views

CXPACKET Waits performance tune for SQL Server 2008

I have a SQL Server 2008 query that is working on millions of records. The query is w/in a proc that is run nightly by a job. The query can take a full day to run when I first put it on the server, ...
5
votes
4answers
3k views

Parallelism Best Practices

What are the best practices with setting parallelism in general? I know that SQL Server defaults to 0 to use all available processors, but in what instance would you want to change this default ...
3
votes
2answers
204 views

Bizarre crash in T-SQL - what is it?

What would be a typical situation under which the following error would occur, and what does it mean? Also note that I find myself disconnected from the server when the query fails (but I have not ...