Type conversion in may affect CardinalityEstimate - Convert/cast on selected columns
Type conversion in may affect CardinalityEstimate - Convert/cast on selected columns --- It is viable that this warning be cited when columns are filtered on and the filtering clause involves cast/convert function.
But, it seems to be an overreach when converted/casted columns are simply cited in the selected / projected column list and not at all in filtering clause.
Upvotes: 1<=-=Dec 28 2017 10:38AM=-=>
Defect #11427260 has been filed with our Product group on your behalf – Karly Shockley<=-=Dec 28 2017 11:34AM=-=>
Transact SQL � Warning � �Type conversion in expression may affect �CardinalityEstimate� in query plan choice�
Jeff M commented
+1 on Martin Freeman's comment. I ran into this as well and this false positive noise hinders the discovery of legitimate performance problems. Ref. https://stackoverflow.com/questions/55546183/concatenation-of-int-columns-warning-type-conversion-in-expression-causes-cardi/55578486#55578486
Nathan Phillip Brink commented
See also https://dba.stackexchange.com/a/34331 which refers to Connect 695556
Mark Freeman commented
This makes it harder to find real problems when practically every plan shows this warning for no good reason.