Cardinality Estimation for a Predicate on a COUNT Expression
Paul White takes you on an optimizer journey, exploring how SQL Server comes up with cardinality estimates for COUNT queries.
2017-05-17
3,222 reads
Paul White takes you on an optimizer journey, exploring how SQL Server comes up with cardinality estimates for COUNT queries.
2017-05-17
3,222 reads
Aaron Bertrand shares some insight about early changes to Plan Explorer that help to provide you with the most accurate information we can.
2016-04-04
2,780 reads
The Query Optimiser needs a good estimate of the number of rows likely to be returned by each physical operator in order to select the best query plan from the most likely alternatives. Sometimes these estimates can go so wildly wrong as to result in a very slow query. Joe Sack shows how it can happen with SQL Queries on a data warehouse with a star schema.
2012-12-10
1,163 reads
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I have some data in a table that looks like this:
BeerID BeerName brewer beerdescription 1 Becks Interbrew Beck's is a German-style pilsner beer 2 Fat Tire New Belgium Toasty malt, gentle sweetness, flash of fresh hop bitterness. 3 Mac n Jacks Mac & Jack's Brewery This beer erupts with a floral, hoppy taste 4 Alaskan Amber Alaskan Brewing Alaskan Brewing Amber Ale is an "alt" style beer 8 Kirin Kirin Brewing Kirin Ichiban is a Lager-type beerIf I run this, what is returned?
select t1.[key]
from openjson((select t.* FROM Beer AS t for json path)) t1 See possible answers