HP NonStop SQL/MP User Manual

HP NonStop SQL/MP Programming Manual for C—429847-008
C-1
C Maximizing Local Autonomy
This appendix describes about the local autonomy in the NonStop SQL/MP
network-distributed database.
Topics include:

Using a Local Partition

Using TACL DEFINEs on page C-2

Using Current Statistics on page C-2

Skipping Unavailable Partitions on page C-3
Local autonomy in a network-distributed database ensures that a program can access
data on the local node, regardless of the availability of remote SQL objects. In some
cases, the design of NonStop SQL/MP allows for local autonomy. For example, if a
DDL change alters a table on \NODEA when \NODEB is unavailable, an SQL program
file on \NODEB that uses the altered \NODEA table is not marked as invalid. The
invalid SQL program on \NODEB that is erroneously marked as valid is detected at run
time by the timestamp check and then automatically recompiled.
If your program accesses a network-distributed database, you can maximize local
autonomy by following these guidelines:

Use a local partition, rather than the primary partition, as the table name.

Use TACL DEFINEs.

Use current statistics.

Skip unavailable partitions.
For collations, NonStop SQL/MP supports run-time node autonomy, because collations
are stored in an SQL object’s file label and within expressions that operate on the SQL
objects.
For example, suppose that you create a partitioned table named TABLEA with
partitions on \NEWYORK and \PARIS. TABLEA requires the collation
\NEWYORK.$SQL.COLLATE.FRENCH. If \NEWYORK goes down, programs on
\PARIS that refer to TABLEA continue to run because they get the collation information
from the TABLEA file label. However, the recompilation of a program on \PARIS that
uses TABLEA fails because the \NEWYORK.$SQL.COLLATE.FRENCH collation is not
available.
Using a Local Partition
If your program accesses a remote partition, the SQL compiler looks for information
about the table in a remote catalog. If the remote node is down, the SQL compilation
fails. However, if your program uses a local partition, the SQL compiler looks for the
information in a local catalog. If the local node and data are available, the SQL
compilation is successful.

HP NonStop SQL/MP Specifications

General

Platform	HP NonStop Servers
Data Model	Relational
SQL Standard	ANSI SQL
Concurrency Control	Multi-Version Concurrency Control (MVCC)
Fault Tolerance	Yes
High Availability	Yes
Category	Database Software
Initial Release	1980s
Operating System	HP NonStop OS
License	Proprietary
Type	Relational Database Management System
Transaction Management	ACID Compliance
Developer	Hewlett Packard Enterprise

Summary

1. Introduction

Developing a C Program

Outlines the process of creating C programs with embedded SQL statements.

Dynamic SQL

Describes how to construct, compile, and run SQL statements at runtime.

2. Host Variables

3. SQL/MP Statements and Directives

4. Data Retrieval and Modification

Single-Row SELECT Statement

Retrieves a single row of data from tables or views into host variables.

Multirow SELECT Statement

Returns multiple rows from tables or views, one row at a time, using cursors.

INSERT Statement

Inserts one or more rows into a table or protection view using host variables.

Using SQL Cursors

Explains how to use named pointers to access sets of rows one at a time.

5. SQL/MP System Procedures

6. Explicit Program Compilation

Explicit Program Compilation

Outlines the general steps for compiling C programs with embedded SQL.

Developing a C Program in the Guardian Environment

Details C program development within the Guardian environment.

Developing a C Program in the OSS Environment

Developing a C Program in a PC Host Environment

7. Program Execution

Required Access Authority

Specifies the access permissions needed to run NonStop SQL program files.

Entering the TACL RUN Command

Running a Program in the OSS Environment

8. Program Invalidation and Automatic SQL Recompilation

Program Invalidation

Explains how SQL program files can become invalid due to changes or errors.

Causes of Program Invalidation

Automatic SQL Recompilation

Describes the run-time recompilation process invoked by the SQL executor.

9. Error and Status Reporting

Returning Error and Warning Information

Using the WHENEVER Directive

10. Dynamic SQL Operations

Uses for Dynamic SQL

Identifies scenarios where dynamic SQL programs are beneficial.

Dynamic SQL Statements

Summarizes dynamic SQL statements usable in a C program.

Dynamic SQL Features

11. Character Processing Rules (CPRL) Procedures

Appendix B: Memory Considerations

Estimating Memory Requirements

Avoiding Memory Stack Overflows

Provides guidelines to prevent stack overflows for SQL statements.