SQL Tuning [Electronic resources] نسخه متنی

Conventions Used in This Book

The following typographical conventions are
used in this book:

Italic

Used for emphasis, for the first use of a
technical term, for example URLs, and for file and directory names.

Constant width

Used for SQL examples, file contents, and examples of output.

Hungarian_Constant_Width

Used for table and column names, whether in SQL or referring to SQL
from within the body of a paragraph. Also used for alias names and
node names, which are elements in a SQL diagram
that theoretically refer to table aliases, even when a diagram
sometimes shows an abstract tuning problem without referring to a
specific SQL statement that corresponds to that problem. Since
aliases are usually made an acronym based on a table name, such as
CT for the column
Code_Translations, aliases are usually pure
uppercase.

(C, O, OT, OD, ODT, P, S, A)

A constant-width list of aliases, node
names, or columns, bounded in parentheses. I borrow this
n-tuple notation from mathematics to indicate an
ordered list of items. In the example case, the notation describes a
join order between nodes in a join diagram, representing table
aliases. In another example, (Code_Type,
Code) would represent a pair of indexed columns in
a two-column index, with Code_Type as the first
column. Alternately, Code_Translations(Code_Type,
Code) represents the same index, while specifying that it
is on the table Code_Translations.

<Constant_Width_Italic>

Constant-width italic text inside
angle brackets describes missing portions of a SQL statement
template, which you must fill in, that represents a whole class of
statements. For example,
SomeAlias.Leading_Indexed_Column=<Expression>
represents any equality condition matching the leading column of an
index with any other expression.

UPPERCASE

In SQL, uppercase indicates
keywords, function names, and tables or views pre-defined by the
database vendor (such as Oracle's
PLAN_TABLE).

Pay
special attention to notes set apart from the text with the following
icons:

Indicates a general note, tip, or suggestion. For example, I sometimes use notes for asides specific to a particular database vendor, in the midst of an otherwise vendor-independent discussion.

Indicates a warning, used to point out special pitfalls I've seen relating to the current discussion.