A vital component inside the query optimizer is the cardinalityestimator,  these algorithms calculate the estimated numberof rows that will be outputted from each operator.  In SQL Server 2014, therehave been many changes aimed at giving a more accurate number of rows, andtherefore better plans.This session will be a look at these changes, comparing andcontrasting with SQL2012/2008 to see how they help.
Presented by Dave Ballantyne at SQLBits XIV
MP4 Video HD 537 MB