SQL/MX 3.x Query Guide (H06.22+, J06.11+)

HP NonStop SQL/MX Query Guide—640323-001
1
Legal Notices 1
Legal Notices 1
What’s New in This Manual vii
Manual Information vii
New and Changed Information vii
About This Manual xi
Audience xi
Organization xi
Related Documentation xii
Notation Conventions xv
1. Compiling and Executing a Query
Overview 1-1
How the Compiler Works 1-2
Compilation Steps 1-2
Parsing, Binding, and Normalizing 1-3
Query Plan Caching 1-5
Improving Query Performance 1-6
Factors That Can Affect Compile Time 1-19
How the Executor Processes the Plan 1-19
2. Accessing SQL/MX Data
Access Methods 2-1
Storage-Key Access 2-1
Index-Only Access 2-2
Alternate Index Access 2-4
Full Table Scan 2-5
Understanding Unexpected Access Paths 2-9
MultiDimensional Access Method (MDAM)
2-13
Specifying MDAM
2-13
Comparing MDAM With Single Subset Access 2-14
How MDAM Processes Queries 2-15
Influencing the Optimizer to Use MDAM 2-17
Controlling the Number of Key Columns Used by MDAM 2-18
MDAM’s Use of DENSE and SPARSE Algorithms 2-18
3. Keeping Statistics Current
Histogram Statistics 3-1
Updating Histogram Statistics 3-2
Sampling and UPDATE STATISTICS 3-5