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  • SQL TuneIn Zagreb 2014 – Session material

    I spent the last few days in Zagreb, Croatie, at the third edition of the SQL TuneIn conference, and I had a very good time here. Nice company, good sessions, and awesome audiences. I presented my “Understanding Execution Plans” precon to a small but interested audience on Monday. Participants have received a download link for the slide deck. On ...
  • Cardinality Estimation for Disjunctive Predicates in SQL Server 2014

    Introduction Back in January 2014, I wrote an article for SQLperformance.com describing the cardinality estimation process for queries with multiple predicates, from the point of view of the old and new cardinality estimators. The article describes the various behaviours and formulas involved, along with the usual sprinkling of documented and ...
    Posted to Page Free Space (Weblog) by Paul White on April 15, 2014
  • Cardinality Estimation Bug with Lookups

    Estimated row counts on key or RID lookups where a filtering predicate is applied can be wrong in SSMS execution plans.  This error does not affect the optimizer’s ultimate plan selection, but it does look odd.  There are other cases where estimated row counts are inconsistent (for defensible reasons) but the behaviour shown in this post ...
    Posted to Page Free Space (Weblog) by Paul White on October 15, 2012
  • Heaps of Trouble?

    If you’re not already a regular reader of Brad Schulz’s blog, you’re missing out on some great material.  In his latest entry, he is tasked with optimizing a query run against tables that have no indexes at all.  The problem is, predictably, that performance is not very good.  The catch is that we are not allowed to create any ...
    Posted to Page Free Space (Weblog) by Paul White on December 9, 2010
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