This book is for System and Database Administrators.
This book describes the query processor in Adaptive Server® Enterprise and how it is used to optimize query processing in Adaptive Server. It also describes how to create and use abstract query plans.
Chapter 1, “Understanding Query Processing,” provides an overview of the query processor in Adaptive Server Enterprise.
Chapter 2, “Using showplan,” describes the messages printed by the showplan utility.
Chapter 3, “Displaying Query Optimization Strategies and Estimates,” describes the messages printed by the set commands designed for query optimization.
Chapter 4, “Parallel Query Processing,” describes how Adaptive Server supports horizontal and vertical parallelism for query execution.
Chapter 5, “Controlling Optimization,” describes query processing options that affect the query processor’s choice of join order, index, I/O size, and cache strategy
Chapter 6, “Using Statistics to Improve Performance,” explains how and when to use the commands that manage statistics.
Chapter 7, “Introduction to Abstract Plans,” reviews the basic concepts of abstract plans.
Chapter 8, “Creating and Using Abstract Plans,” provides an overview of the commands used to capture abstract plans and to associate incoming SQL queries with saved plans.
Chapter 9, “Abstract Query Plan Guide,” provides guidelines for your use in writing abstract plans.
Chapter 10, “Managing Abstract Plans with System Procedures,” provides an introduction to the basic functionality and use of system procedures for working with abstract plans.
Chapter 11, “Query Processing Metrics,”explains what query processing metrics are, what they do, and how you can use them.
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This section describes the conventions used in this manual.
SQL is a free-form language. There are no rules about the number of words you can put on a line or where you must break a line. However, for readability, all examples and most syntax statements in this manual are formatted so that each clause of a statement begins on a new line. Clauses that have more than one part extend to additional lines, which are indented. Complex commands are formatted using modified Backus Naur Form (BNF) notation.
Table 1 shows the conventions for syntax statements that appear in this manual:
Element |
Example |
|---|---|
Command names, procedure names, utility names, and other keywords display in sans serif font. |
select sp_configure |
Database names and datatypes display in sans serif font. |
master database |
File names, variables, and path names display in italics. |
sql.ini file column_name $SYBASE/ASE directory |
Variables—or words that stand for values that you fill in—when they are part of a query or statement, display in italics in Courier font. |
|
Type parentheses as part of the command. |
|
Double colon, equals sign indicates that the syntax is written in BNF notation. Do not type this symbol. Indicates “is defined as”. |
|
Curly braces mean that you must choose at least one of the enclosed options. Do not type the braces. |
|
Brackets mean that you have the option to choose one or more of the enclosed choices. Do not type the brackets. |
|
The comma means that you may choose as many of the options shown as you want. Separate your choices with commas as part of the command. |
|
The pipe or vertical bar ( | ) means that you may select only one of the options shown. |
|
An ellipsis (...) means that you can repeat the last unit as many times as you like. |
You must buy at least one thing and give its price. You may choose a method of payment: one of the items enclosed in square brackets. You may also choose to buy additional things: as many of them as you like. For each thing you buy, give its name, its price, and (optionally) a method of payment. |
Syntax statements (displaying the syntax and all options for a command) appear as follows:
sp_dropdevice [device_name]
For a command with more options:
select column_name from table_name where search_conditions
In syntax statements, keywords (commands) are in normal font and identifiers are in lowercase. Italics show user-supplied words.
Examples showing the use of Transact-SQL™ commands are printed like this:
select * from publishers
Examples of output from the computer appear as follows:
pub_id pub_name city state ------- --------------------- ----------- ----- 0736 New Age Books Boston MA 0877 Binnet & Hardley Washington DC 1389 Algodata Infosystems Berkeley CA (3 rows affected)
In this manual, most of the examples are in lowercase. However, you can disregard case when typing Transact-SQL keywords. For example, SELECT, Select, and select are the same.
Adaptive Server sensitivity to the case of database objects, such as table names, depends on the sort order installed on Adaptive Server. You can change case sensitivity for single-byte character sets by reconfiguring the Adaptive Server sort order. For more information, see the System Administration Guide.
This document is available in an HTML version that is specialized for accessibility. You can navigate the HTML with an adaptive technology such as a screen reader, or view it with a screen enlarger.
Adaptive Server 15.0 and the HTML documentation have been tested for compliance with U.S. government Section 508 Accessibility requirements. Documents that comply with Section 508 generally also meet nonU.S. accessibility guidelines, such as the World Wide Web Consortium (W3C) guidelines for Web sites.
The online help for this product is also provided in HTML, which you can navigate using a screen reader.
You might need to configure your accessibility tool
for optimal use. Some screen readers pronounce text based on its
case; for example, they pronounce ALL UPPERCASE TEXT as initials,
and MixedCase Text as words. You might find it helpful to configure
your tool to announce syntax conventions. Consult the documentation
for your tool.
For information about how Sybase supports accessibility, see Sybase Accessibility. The Sybase Accessibility site includes links to information on Section 508 and W3C standards.
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