1. EXECUTION PLANS
Quick Dive

2. ABOUT ME
@shawsql

3. I OWE EVERYTHING TO…

4. WHAT WE WON’T TALK ABOUT
Execution plan cache
Performance tuning
DMV’s (maybe a little)
XML, parallelism, partitioning, etc.
Statistics
Politics

5. KEY CONCEPTS T-SQL is non-procedural
This means the language does not tell how to retrieve the data
Execution Plans are cost-based
This means even a good plan may not necessarily be the best plan and the best plan may never be known
Execution Plans are broken up into logical and physical operators
Logical operations are expressed by physical operations

6. EXECUTION PROCESS

7. EXECUTION PLANS Each step in an execution plan is a physical operator
Plans read from left to right
Bar thickness represents amount of data
Outer tables on top, inner tables on bottom
Plans are either “trivial” or “full”

8. DEMO
Trivial Plans
Index\Table Scans\Seeks
Bookmark Lookups

9. JOIN TYPES Hash - Build table and probe table
- In memory, grace, recursive
Nested Loops
- Outer table and inner table
- Best when outer input is small and inner output is indexed

10. JOIN TYPES Merge - Each input is sorted
- Best for large, pre-sorted tables

11. DEMO
Join Types

12. TOOL TIP TIME
A lot of information but most not necessarily relevant.

13. Best Practices Locate the step with the highest cost
Eliminate table scans
Update statistics
Avoid bookmark lookups by using clustered indexes or covering indexes