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Why am I getting an implicit conversion of Int / Smallint to Varchar, and is it really impacting Cardinality Estimates?
I'm trying to trouble shoot a slow performing query using Show Plan Analysis (SSMS) on the actual execution plan. The Analysis tool points out that estimates for number of rows are off from returned ...
- 257
10
votes
1
answer
8k
views
"Warnings: Operation caused residual I/O" versus key lookups
I've seen this warning in SQL Server 2017 execution plans:
Warnings: Operation caused residual IO [sic]. The actual number of rows read was (3,321,318), but the number of rows returned was 40.
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