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Answer by Kev Riley
Whether or not it is desirable is based on the context of the query, the data and the execution plan.Spools are used as optimization techniques, but can seem costly as they incur writes to tempdb....
View ArticleAnswer by Grant Fritchey
That's one of the more costly operations that can occur. It basically means that the optimizer thought it needed to build it's own index in order to satisfy the query. In general you need to look at...
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