This course is designed to teach the students how to prevent SQL performance problems and how to improve the performance of existing SQL.
Prerequisiti
Familiarity with SQL
Familiarity with Db2 12 for z/OS
Familiarity with Db2 12 for z/OS application programming
Obiettivi
After completing this course, students will be able to:
Understand and design better indexes
Determine how to work with the optimizer (avoid pitfalls, provide guidence)
Optimize multi-table access
Work with subqueries
Avoid locking problems
Use accounting traces and other tools to locate performance problems in existing SQL and more
Destinatari
This course is for Db2 12 for z/OS application developers, Db2 12 for z/OS DBAs, and anyone else with a responsibility for SQL performance and tuning in a Db2 12 for z/OS environment.
Contenuti
Introduction to SQL performance and tuning
Performance issues
Simple example
Visualizing the problem
Summary Performance analysis tools
Components of response time
Time estimates with VQUBE3
SQL EXPLAIN
The accounting trace
The bubble chart
Performance thresholds Index basics
Indexes
Index structure
Estimating index I/Os
Clustering index
Index page splits Access paths
Classification
Matching versus Screening
Variations
Hash access
Prefetch
Caveat More on indexes
Include index
Index on expression
Random index
Partitioned and partitioning, NPSI and DPSI
Page range screening
Features and limitations Tuning methodology and index cost
Methodology
Index cost: Disk space
Index cost: Maintenance
Utilities and indexes
Modifying and creating indexes
Avoiding sorts Index design
Approach
Designing indexes Advanced access paths
Prefetch
List prefetch
Multiple index access
Runtime adaptive index Multiple table access
Join methods
Join types
Designing indexes for joins
Predicting table order Subqueries
Correlated subqueries
Non-correlated subqueries
ORDER BY and FETCH FIRST with subqueries
Global query optimization
Virtual tables
Explain for subqueries Set operations (optional)
UNION, EXCEPT, and INTERSECT
Rules
More about the set operators
UNION ALL performance improvements Table design (optional)
Number of tables
Clustering sequence Denormalization
Materialized query tables (MQTs)
Temporal tables
Archive enabled tables Working with the optimizer
Indexable versus non-indexable predicates
Boolean versus non-Boolean predicates
Stage 1 versus stage 2
Filter factors
Helping the optimizer
Pagination Locking issues
The ACID test
Reasons for serialization
Serialization mechanisms
Transaction locking
Lock promotion, escalation, and avoidance More locking issues (optional)
