</indexterm>

<para>

Lines (<type>line</type>) are represented by the linear equation Ax + By

+ C = 0, where A and B are not both zero. Values of

type <type>line</type> is input and output in the following form:

Lines are represented by the linear

equation <replaceable>A</>x + <replaceable>B</>y + <replaceable>C</> = 0,

where <replaceable>A</> and <replaceable>B</> are not both zero. Values

of type <type>line</type> are input and output in the following form:

<synopsis>

{ <replaceable>A</replaceable>, <replaceable>B</replaceable>, <replaceable>C</replaceable> }

</synopsis>

<literal>(<replaceable>x1</replaceable>,<replaceable>y1</replaceable>)</literal>

and

<literal>(<replaceable>x2</replaceable>,<replaceable>y2</replaceable>)</literal>

are two(different) points on the line.

are two different points on the line.

</para>

</sect2>

</indexterm>

<para>

Line segments(<type>lseg</type>)are represented by pairs of points.

Values of type <type>lseg</type> are specified using any of the following

syntaxes:

Line segments are represented by pairs of points that are the endpoints

of the segment.Values of type <type>lseg</type> are specified using any

of the followingsyntaxes:

<synopsis>

[ ( <replaceable>x1</replaceable> , <replaceable>y1</replaceable> ) , ( <replaceable>x2</replaceable> , <replaceable>y2</replaceable> ) ]

always sets <literal>FOUND</literal> to true.

</para>

<para>

For <command>INSERT</>/<command>UPDATE</>/<command>DELETE</> with

<literal>RETURNING</>, <application>PL/pgSQL</application> reports

an error for more than one returned row, even when

<literal>STRICT</literal> is not specified. This is because there

is no option such as <literal>ORDER BY</> with which to determine

which affected row should be returned.

</para>

<para>

If <literal>print_strict_params</> is enabled for the function,

you will get information about the parameters passed to the

query in the <literal>DETAIL</> part of the error message produced

when the requirements of STRICT are not met. You can change this

setting on a system-wide basis by setting

then when an error is thrown because the requirements

of <literal>STRICT</> are not met, the <literal>DETAIL</> part of

the error message will include information about the parameters

passed to the query.

You can change the <literal>print_strict_params</>

setting for all functions by setting

<varname>plpgsql.print_strict_params</>, though only subsequent

function compilations will be affected. You can also enable it

on a per-function basis by using a compiler option:

on a per-function basis by using a compiler option, for example:

<programlisting>

CREATE FUNCTION get_userid(username text) RETURNS int

AS $$

END

$$ LANGUAGE plpgsql;

</programlisting>

</para>

<para>

For <command>INSERT</>/<command>UPDATE</>/<command>DELETE</> with

<literal>RETURNING</>, <application>PL/pgSQL</application> reports

an error for more than one returned row, even when

<literal>STRICT</literal> is not specified. This is because there

is no option such as <literal>ORDER BY</> with which to determine

which affected row should be returned.

On failure, this function might produce an error message such as

<programlisting>

ERROR: query returned no rows

DETAIL: parameters: $1 = 'nosuchuser'

CONTEXT: PL/pgSQL function get_userid(text) line 6 at SQL statement

</programlisting>

</para>

<note>

</sect2>

<sect2 id="plpgsql-get-diagnostics-context">

<title>Obtaining the Call Stack Context Information</title>

<title>Obtaining Current Execution Information</title>

<para>

The <command>GET <optional> CURRENT </optional> DIAGNOSTICS</command>

command retrieves information about current execution state (whereas

the <command>GET STACKED DIAGNOSTICS</command> command discussed above

reports information about the execution state as of a previous error).

This command has the form:

</para>

<synopsis>

GET <optional> CURRENT </optional> DIAGNOSTICS <replaceable>variable</replaceable> { = | := } <replaceable>PG_CONTEXT</replaceable> <optional> , ... </optional>;

GET <optional> CURRENT </optional> DIAGNOSTICS <replaceable>variable</replaceable> { = | := } <replaceable>item</replaceable> <optional> , ... </optional>;

</synopsis>

<para>

item <varname>PG_CONTEXT</> will return a text string with line(s) of

text describing the call stack. The firstrow refers to the

item <literal>PG_CONTEXT</> will return a text string with line(s) of

text describing the call stack. The firstline refers to the

current function and currently executing <command>GET DIAGNOSTICS</command>

command. The second and any subsequentrows refer to the calling functions

up the call stack.

command. The second and any subsequentlines refer to calling functions

furtherup the call stack. For example:

<programlisting>

CREATE OR REPLACE FUNCTIONpublic.outer_func() RETURNS integer AS $$

CREATE OR REPLACE FUNCTION outer_func() RETURNS integer AS $$

BEGIN

RETURN inner_func();

END;

$$ LANGUAGE plpgsql;

CREATE OR REPLACE FUNCTIONpublic.inner_func() RETURNS integer AS $$

CREATE OR REPLACE FUNCTION inner_func() RETURNS integer AS $$

DECLARE

stack text;

BEGIN

SELECT outer_func();

NOTICE: --- Call Stack ---

PL/pgSQL function inner_func() line4 at GET DIAGNOSTICS

PL/pgSQL function inner_func() line5 at GET DIAGNOSTICS

PL/pgSQL function outer_func() line 3 at RETURN

CONTEXT: PL/pgSQL function outer_func() line 3 at RETURN

outer_func

------------

1