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Allow referring to functions without arguments when unique

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In DDL commands referring to an existing function, allow omitting the
argument list if the function name is unique in its schema, per SQL
standard.

This uses the same logic that the regproc type uses for finding
functions by name only.

Reviewed-by: Michael Paquier <michael.paquier@gmail.com>
This commit is contained in:
Peter Eisentraut
2017-03-09 23:58:48 -05:00
parent 3f6ea5fc8d
commit aefeb68741
17 changed files with 143 additions and 28 deletions
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35
doc/src/sgml/ref/drop_function.sgml
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@ -21,7 +21,7 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
DROP FUNCTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) [, ...]
DROP FUNCTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ ( [ [ <replaceable class="parameter">argmode</replaceable> ] [ <replaceable class="parameter">argname</replaceable> ] <replaceable class="parameter">argtype</replaceable> [, ...] ] ) ] [, ...]
[ CASCADE | RESTRICT ]
</synopsis>
</refsynopsisdiv>
@ -56,7 +56,8 @@ DROP FUNCTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> (
<term><replaceable class="parameter">name</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing function.
The name (optionally schema-qualified) of an existing function. If no
argument list is specified, the name must be unique in its schema.
</para>
</listitem>
</varlistentry>
@ -141,14 +142,40 @@ DROP FUNCTION sqrt(integer);
<programlisting>
DROP FUNCTION sqrt(integer), sqrt(bigint);
</programlisting></para>
<para>
If the function name is unique in its schema, it can be referred to without
an argument list:
<programlisting>
DROP FUNCTION update_employee_salaries;
</programlisting>
Note that this is different from
<programlisting>
DROP FUNCTION update_employee_salaries();
</programlisting>
which refers to a function with zero arguments, whereas the first variant
can refer to a function with any number of arguments, including zero, as
long as the name is unique.
</para>
</refsect1>
<refsect1 id="SQL-DROPFUNCTION-compatibility">
<title>Compatibility</title>
<para>
A <command>DROP FUNCTION</command> statement is defined in the SQL
standard, but it is not compatible with this command.
This command conforms to the SQL standard, with
these <productname>PostgreSQL</productname> extensions:
<itemizedlist>
<listitem>
<para>The standard only allows one function to be dropped per command.</para>
</listitem>
<listitem>
<para>The <literal>IF EXISTS</literal> option</para>
</listitem>
<listitem>
<para>The ability to specify argument modes and names</para>
</listitem>
</itemizedlist>
</para>
</refsect1>