"Residual I/O Warnings" is a common issue which alert us that the query is reading more data than it should.
Have you any idea how i can improve that ?
In order to examine the issue we must some sample data and database structure to repriduce the scenario in order to play with (the query is needed mu can be found in the XML as well).
(1) Did you noticed this alert:
Missing Index (Impact 79.2813): CREATE NONCLUSTERED INDEX [<Name of Missing Index, sysname,>] ON Schema2.Object7 (Column5,Column4,Column9) INCLUDE (Column3,Column8,Column6,Column10)
Did you try to create such index?
(2) In the meantime, the following free book online provide an awesome explanation following step by step full scenario
You can jump to page 17 where it looks closer on the error “Operation caused residual IO." but better to have this opportunity and read from the start (page 1).
Please inform us if there anything that still open after you read it :-)