Conventions Used in This Book


Used for filenames, directory names, string-bound constants, and URLs. It is also used for emphasis, and for the first use of a technical term.

Constant width

Used for keywords, identifiers (such as tables and columns), data types, examples, and to show the contents of files, and the output of commands.

Constant width italic

Used in syntax descriptions to indicated user-defined items.

Constant width bold

Indicates user input within examples.


Used within syntax descriptions, uppercase usually indicates keywords.


Used within syntax descriptions, lowercase usually indicates user-defined items, such as variables and identifiers.

[ ]

Used within syntax descriptions, square brackets enclose optional items, which are separated from one another by pipes (|).

{ }

Used within syntax descriptions, curly brackets enclose a set of items from which you must choose one.


Used within syntax descriptions, ellipses indicate repeating information. Used within examples, ellipses indicate that a section of unimportant information was removed from the example output to improve readability and conserve space.

Note: The owl icon indicates a tip, suggestion, or general note. For example, we'll let you know that PostgreSQL supports the use of all ISO standard time zone abbreviations in the section on time zones.


The turkey icon indicates a warning or caution. For example, we'll warn you ahead of time that using the DELETE command without a WHERE clause can delete all of your data from a table.