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You are creating indexes in a data warehouse.
You have a dimension table named Table1 that has 10,000 rows. The rows are used to generate several reports.
The reports join a column that is the primary key.
The execution plan contains bookmark lookups for Table1.
You discover that the reports run slower than expected.
You need to reduce the amount of time it takes to run the reports.
Solution: You create a nonclustered index on the primary key column that does NOT include columns.
Does this meet the goal?
A. Yes
B. No
I think B is correct.
We need covering non-cluster index to avoid bookmark lookup. Covering means that index is created on or includes all required columns.
“Index on the primary key column that does NOT include columns” is definitely not a covering index.
https://www.sqlpassion.at/archive/2017/03/13/the-performance-penalty-of-bookmark-lookups-in-sql-server/