Join Joey D'Antoni for an in-depth discussion in this video Included column explanation, part of SQL Server Performance for Developers.
- In our last demo, you may have noticed that…our CREATE INDEX statement had…an "include" option at the end.…This meant we included a couple of columns in our index,…and what does that mean?…When we step back and talk about indexing structure on disk…SQL Server, and all other relational databases…for the most part, use a B-tree structure.…The exception to this is columnstore indexes,…which are out of scope for this module.…However, we have that B-tree.…We want that B-tree to be narrow,…and we want it to be efficient…so that we can seek through that tree very efficiently…to retrieve the values off of disk that we have.…
That makes our index very efficient, but sometimes,…we need more columns than that to service our query.…One of the ways we can do this and keep our key level small,…is use this "include" option,…and these included columns are stored…at the leaf level of our index B-tree.…What that means is that the index is…storing all the columns we want,…but they're not a part of our initial lookup,…but they are in the index,…
- Query execution
- How to read an execution plan
- What not to do with SQL Server
- Why cursors are bad
- Why scalar UDFs are expensive
- Datatypes and design
- What is a columnstore index?
- Transaction isolation
Skill Level Intermediate
1. Query Execution
2. What Not to Do with SQL Server
3. Datatypes and Design
4. Temporary Objects
7. Isolation Levels
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