SQL/MX 3.1 Query Guide (H06.23+, J06.12+)

HP NonStop SQL/MX Release 3.1 Query Guide—663851-001
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About This Manual
This guide describes the use and formulation of queries, how to understand query
execution plans, and how to affect the performance of NonStop SQL/MX databases. It
also provides information about:

How to improve query performance

How the SQL/MX optimizer chooses a query execution plan

How you can influence the optimizer’s choice of a plan
Audience
This guide is intended for database administrators and application programmers who
use NonStop SQL/MX to query an SQL/MX database and who have a particular
interest in issues related to query performance. Readers are expected to be data
processing professionals who have familiarity with general issues related to the
performance of database management systems and who understand relational
database theory and terminology.
You should also be familiar with the operating system and one of the host
programming languages, such as C/C++ or COBOL.
Organization
Examples are shown in interactive form, such as that used by the SQL/MX
conversational interface (MXCI) and Visual Query Planner (VQP).
Section 1, Compiling and Executing a Query Introduces the NonStop SQL/MX compiler
and executor.
Section 2, Accessing SQL/MX Data
Provides information about access methods.
Section 3, Keeping Statistics Current
Provides information about updating statistics
and histogram statistics.
Section 4, Reviewing Query Execution
Plans
Describes how to read query execution
plans.
Section 5, Forcing Execution Plans
Describes how to force query execution
plans.
Section 6, Query Plan Caching
Describes how query plan caching works and
how to view query plan caching statistics.
Section 7, SQL/MX Operators
Provides information about operators used in
query execution plans.
Section 8, Parallelism
Describes how NonStop SQL/MX performs
parallelism.
TP663851.fm Page xiii Monday, October 17, 2011 11:48 AM