Freigeben über

Parallel Query Execution Presentation

  • Artikel

For those of you readers who've been wondering whatever happened to me, I've been rather busy.  Among other activities, I've been writing a chapter for Kalen Delaney's upcoming fourth book in the Inside SQL Server 2005 series: Query Tuning and Optimization.

I am hoping to resurrect my blog and to get things started, I'm posting a presentation that I recently delivered to the Pacific Northwest SQL Server User's Group.  Several attendees asked whether they could have copies of this presentation, so here it is.

Parallel Query Execution.pdf

Comments

  • Anonymous
    May 16, 2007
    The Non-Parallelizable “Stuff” slide in the attached presentation contained a somewhat ambiguous statement that "TSQL UDFs and CLR UDFs with data access" force a serial plan.  This statement made it sound like TSQL UDFs without data access are compatible with parallel plans.  In fact, ALL TSQL UDFs force serial plans.  CLR UDFs with data access force serial plans.  CLR UDFs without data access are compatible with parallel plans.  I apologize for any confusion and I've updated the slide deck to make it clearer.

  • Anonymous
    September 24, 2008
    I've received a couple of questions in email and in comments about deadlocks involving mysterious-sounding

  • Anonymous
    January 01, 2010
    Hey Craig.  I am a SQL Server MVP and I just stumbled across your Parallelism presentation.  Would you mind if I gave this talk to various user groups and SQL Saturdays?  I live in the southeast US and most of the activity would be there.  I would actually like to submit it to present at the 2010 European PASS Conference if you would allow that too. Please drop me an email at kgboles at earthlink dt net. Thanks in advance! Best, Kevin G. Boles SQL Server MVP

  • Anonymous
    January 13, 2011
    The comment has been removed

  • Anonymous
    January 17, 2011
    The comment has been removed

  • Anonymous
    December 15, 2011
    Hello Mr. Freedman, I'm curious if you have a script that can reliably generate the Intra-Query Parallel Threads deadlock? If so, any chance of sharing it? Thanks, Grant

  • Anonymous
    December 16, 2011
    I'm afraid I do not have a script to generate an intra-query parallel deadlock.  Sorry.

  • Anonymous
    January 13, 2015
    Hi Craig, Thank you for the pdf. I found it very informative. However, could I suggest that you also include a section, or warning, that query plans can be quite different for a parallelised query versus the same query not parallelised. This can mean that the non parallelised query actually runs much faster than the parallelised query. I'm guessing that you have seen this. I have found it to be an issue on several occasions, which resulted in a maxdop 1 hint on the queries. Perhaps you could include a section on plan selection in your whitepaper. I have written on this issue a while back - see richardlees.blogspot.com.au/.../parallelised-queries-are-selfish.html.