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Commite56bce5

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Reconsider the handling of procedure OUT parameters.
Commit2453ea1 redefined pg_proc.proargtypes to include the types ofOUT parameters, for procedures only. While that had some advantagesfor implementing the SQL-spec behavior of DROP PROCEDURE, it was prettydisastrous from a number of other perspectives. Notably, since theprimary key of pg_proc is name + proargtypes, this made it possible tohave multiple procedures with identical names + input arguments anddiffering output argument types. That would make it impossible to callany one of the procedures by writing just NULL (or "?", or any otherdata-type-free notation) for the output argument(s). The change alsoseems likely to cause grave confusion for client applications thatexamine pg_proc and expect the traditional definition of proargtypes.Hence, revert the definition of proargtypes to what it was, andundo a number of complications that had been added to support that.To support the SQL-spec behavior of DROP PROCEDURE, when there areno argmode markers in the command's parameter list, we perform thelookup both ways (that is, matching against both proargtypes andproallargtypes), succeeding if we get just one unique match.In principle this could result in ambiguous-function failuresthat would not happen when using only one of the two rules.However, overloading of procedure names is thought to be a prettyrare usage, so this shouldn't cause many problems in practice.Postgres-specific code such as pg_dump can defend against anypossibility of such failures by being careful to specify argmodesfor all procedure arguments.This also fixes a few other bugs in the area of CALL statementswith named parameters, and improves the documentation a little.catversion bump forced because the representation of procedureswith OUT arguments changes.Discussion:https://postgr.es/m/3742981.1621533210@sss.pgh.pa.us
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‎doc/src/sgml/catalogs.sgml

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@@ -5905,9 +5905,8 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
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<para>
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An array of the data types of the function arguments. This includes
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only input arguments (including <literal>INOUT</literal> and
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<literal>VARIADIC</literal> arguments), as well as
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<literal>OUT</literal> parameters of procedures, and thus represents
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the call signature of the function or procedure.
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<literal>VARIADIC</literal> arguments), and thus represents
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the call signature of the function.
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</para></entry>
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</row>
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‎doc/src/sgml/plpgsql.sgml

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@@ -480,7 +480,7 @@ $$ LANGUAGE plpgsql;
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<para>
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To call a function with <literal>OUT</literal> parameters, omit the
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output parameter in the function call:
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output parameter(s) in the function call:
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<programlisting>
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SELECT sales_tax(100.00);
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</programlisting>
@@ -523,16 +523,20 @@ $$ LANGUAGE plpgsql;
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</programlisting>
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In a call to a procedure, all the parameters must be specified. For
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output parameters, <literal>NULL</literal> may be specified.
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output parameters, <literal>NULL</literal> may be specified when
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calling the procedure from plain SQL:
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<programlisting>
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CALL sum_n_product(2, 4, NULL, NULL);
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sum | prod
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-----+------
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6 | 8
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</programlisting>
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Output parameters in procedures become more interesting in nested calls,
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where they can be assigned to variables. See <xref
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linkend="plpgsql-statements-calling-procedure"/> for details.
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However, when calling a procedure
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from <application>PL/pgSQL</application>, you should instead write a
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variable for any output parameter; the variable will receive the result
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of the call. See <xref linkend="plpgsql-statements-calling-procedure"/>
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for details.
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</para>
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<para>
@@ -2030,6 +2034,9 @@ BEGIN
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END;
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$$;
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</programlisting>
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The variable corresponding to an output parameter can be a simple
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variable or a field of a composite-type variable. Currently,
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it cannot be an element of an array.
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</para>
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</sect2>
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‎doc/src/sgml/ref/alter_extension.sgml

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@@ -212,12 +212,11 @@ ALTER EXTENSION <replaceable class="parameter">name</replaceable> DROP <replacea
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argument: <literal>IN</literal>, <literal>OUT</literal>,
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<literal>INOUT</literal>, or <literal>VARIADIC</literal>.
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If omitted, the default is <literal>IN</literal>.
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Note that <command>ALTER EXTENSION</command> does not actually pay any
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attention to <literal>OUT</literal> arguments for functions and
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aggregates (but not procedures), since only the input arguments are
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needed to determine the function's identity. So it is sufficient to
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list the <literal>IN</literal>, <literal>INOUT</literal>, and
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<literal>VARIADIC</literal> arguments for functions and aggregates.
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Note that <command>ALTER EXTENSION</command> does not actually pay
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any attention to <literal>OUT</literal> arguments, since only the input
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arguments are needed to determine the function's identity.
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So it is sufficient to list the <literal>IN</literal>, <literal>INOUT</literal>,
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and <literal>VARIADIC</literal> arguments.
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</para>
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</listitem>
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</varlistentry>

‎doc/src/sgml/ref/alter_procedure.sgml

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@@ -96,7 +96,7 @@ ALTER PROCEDURE <replaceable>name</replaceable> [ ( [ [ <replaceable class="para
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The name of an argument.
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Note that <command>ALTER PROCEDURE</command> does not actually pay
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any attention to argument names, since only the argument data
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types areneeded to determine the procedure's identity.
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types areused to determine the procedure's identity.
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</para>
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</listitem>
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</varlistentry>
@@ -108,6 +108,8 @@ ALTER PROCEDURE <replaceable>name</replaceable> [ ( [ [ <replaceable class="para
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<para>
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The data type(s) of the procedure's arguments (optionally
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schema-qualified), if any.
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See <xref linkend="sql-dropprocedure"/> for the details of how
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the procedure is looked up using the argument data type(s).
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</para>
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</listitem>
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</varlistentry>

‎doc/src/sgml/ref/call.sgml

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@@ -55,9 +55,24 @@ CALL <replaceable class="parameter">name</replaceable> ( [ <replaceable class="p
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<term><replaceable class="parameter">argument</replaceable></term>
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<listitem>
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<para>
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An input argument for the procedure call.
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See <xref linkend="sql-syntax-calling-funcs"/> for the full details on
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function and procedure call syntax, including use of named parameters.
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An argument expression for the procedure call.
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</para>
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<para>
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Arguments can include parameter names, using the syntax
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<literal><replaceable class="parameter">name</replaceable> =&gt; <replaceable class="parameter">value</replaceable></literal>.
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This works the same as in ordinary function calls; see
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<xref linkend="sql-syntax-calling-funcs"/> for details.
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</para>
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<para>
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Arguments must be supplied for all procedure parameters that lack
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defaults, including <literal>OUT</literal> parameters. However,
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arguments matching <literal>OUT</literal> parameters are not evaluated,
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so it's customary to just write <literal>NULL</literal> for them.
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(Writing something else for an <literal>OUT</literal> parameter
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might cause compatibility problems with
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future <productname>PostgreSQL</productname> versions.)
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</para>
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</listitem>
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</varlistentry>
@@ -101,7 +116,10 @@ CALL do_db_maintenance();
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<title>Compatibility</title>
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<para>
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<command>CALL</command> conforms to the SQL standard.
119+
<command>CALL</command> conforms to the SQL standard,
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except for the handling of output parameters. The standard
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says that users should write variables to receive the values
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of output parameters.
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</para>
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</refsect1>
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‎doc/src/sgml/ref/comment.sgml

Lines changed: 5 additions & 6 deletions
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@@ -176,12 +176,11 @@ COMMENT ON
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argument: <literal>IN</literal>, <literal>OUT</literal>,
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<literal>INOUT</literal>, or <literal>VARIADIC</literal>.
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If omitted, the default is <literal>IN</literal>.
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Note that <command>COMMENT</command> does not actually pay any attention
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to <literal>OUT</literal> arguments for functions and aggregates (but
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not procedures), since only the input arguments are needed to determine
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the function's identity. So it is sufficient to list the
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<literal>IN</literal>, <literal>INOUT</literal>, and
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<literal>VARIADIC</literal> arguments for functions and aggregates.
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Note that <command>COMMENT</command> does not actually pay
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any attention to <literal>OUT</literal> arguments, since only the input
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arguments are needed to determine the function's identity.
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So it is sufficient to list the <literal>IN</literal>, <literal>INOUT</literal>,
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and <literal>VARIADIC</literal> arguments.
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</para>
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</listitem>
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</varlistentry>

‎doc/src/sgml/ref/drop_procedure.sgml

Lines changed: 81 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -30,10 +30,10 @@ DROP PROCEDURE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [
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<title>Description</title>
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<para>
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<command>DROP PROCEDURE</command> removes the definition ofan existing
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procedure. To execute this command the user must be the
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owner of the procedure. The argument types to the
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procedure must be specified, since several different procedures
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<command>DROP PROCEDURE</command> removes the definition ofone or more
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existing procedures. To execute this command the user must be the
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owner of the procedure(s). The argument types to the
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procedure(s) usually must be specified, since several different procedures
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can exist with the same name and different argument lists.
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</para>
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<term><replaceable class="parameter">name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of an existing procedure. If no
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argument list is specified, the name must be unique in its schema.
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The name (optionally schema-qualified) of an existing procedure.
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</varlistentry>
@@ -69,7 +68,7 @@ DROP PROCEDURE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [
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<para>
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The mode of an argument: <literal>IN</literal>, <literal>OUT</literal>,
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<literal>INOUT</literal>, or <literal>VARIADIC</literal>. If omitted,
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the default is <literal>IN</literal>.
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the default is <literal>IN</literal> (but see below).
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</para>
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</varlistentry>
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The name of an argument.
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Note that <command>DROP PROCEDURE</command> does not actually pay
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any attention to argument names, since only the argument data
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types areneeded to determine the procedure's identity.
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types areused to determine the procedure's identity.
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</para>
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</varlistentry>
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<para>
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The data type(s) of the procedure's arguments (optionally
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schema-qualified), if any.
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See below for details.
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</para>
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</varlistentry>
@@ -121,12 +121,81 @@ DROP PROCEDURE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [
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</variablelist>
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</refsect1>
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124+
<refsect1 id="sql-dropprocedure-notes">
125+
<title>Notes</title>
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127+
<para>
128+
If there is only one procedure of the given name, the argument list
129+
can be omitted. Omit the parentheses too in this case.
130+
</para>
131+
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<para>
133+
In <productname>PostgreSQL</productname>, it's sufficient to list the
134+
input (including <literal>INOUT</literal>) arguments,
135+
because no two routines of the same name are allowed to share the same
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input-argument list. Moreover, the <command>DROP</command> command
137+
will not actually check that you wrote the types
138+
of <literal>OUT</literal> arguments correctly; so any arguments that
139+
are explicitly marked <literal>OUT</literal> are just noise. But
140+
writing them is recommendable for consistency with the
141+
corresponding <command>CREATE</command> command.
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</para>
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<para>
145+
For compatibility with the SQL standard, it is also allowed to write
146+
all the argument data types (including those of <literal>OUT</literal>
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arguments) without
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any <replaceable class="parameter">argmode</replaceable> markers.
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When this is done, the types of the procedure's <literal>OUT</literal>
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argument(s) <emphasis>will</emphasis> be verified against the command.
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This provision creates an ambiguity, in that when the argument list
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contains no <replaceable class="parameter">argmode</replaceable>
153+
markers, it's unclear which rule is intended.
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The <command>DROP</command> command will attempt the lookup both ways,
155+
and will throw an error if two different procedures are found.
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To avoid the risk of such ambiguity, it's recommendable to
157+
write <literal>IN</literal> markers explicitly rather than letting them
158+
be defaulted, thus forcing the
159+
traditional <productname>PostgreSQL</productname> interpretation to be
160+
used.
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</para>
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<para>
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The lookup rules just explained are also used by other commands that
165+
act on existing procedures, such as <command>ALTER PROCEDURE</command>
166+
and <command>COMMENT ON PROCEDURE</command>.
167+
</para>
168+
</refsect1>
169+
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<refsect1 id="sql-dropprocedure-examples">
125171
<title>Examples</title>
126172

173+
<para>
174+
If there is only one procedure <literal>do_db_maintenance</literal>,
175+
this command is sufficient to drop it:
176+
<programlisting>
177+
DROP PROCEDURE do_db_maintenance;
178+
</programlisting>
179+
</para>
180+
181+
<para>
182+
Given this procedure definition:
183+
<programlisting>
184+
CREATE PROCEDURE do_db_maintenance(IN target_schema text, OUT results text) ...
185+
</programlisting>
186+
any one of these commands would work to drop it:
127187
<programlisting>
128-
DROP PROCEDURE do_db_maintenance();
188+
DROP PROCEDURE do_db_maintenance(IN target_schema text, OUT results text);
189+
DROP PROCEDURE do_db_maintenance(IN text, OUT text);
190+
DROP PROCEDURE do_db_maintenance(IN text);
191+
DROP PROCEDURE do_db_maintenance(text);
192+
DROP PROCEDURE do_db_maintenance(text, text); -- potentially ambiguous
129193
</programlisting>
194+
However, the last example would be ambiguous if there is also, say,
195+
<programlisting>
196+
CREATE PROCEDURE do_db_maintenance(IN target_schema text, IN options text) ...
197+
</programlisting>
198+
</para>
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</refsect1>
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132201
<refsect1 id="sql-dropprocedure-compatibility">
@@ -140,10 +209,11 @@ DROP PROCEDURE do_db_maintenance();
140209
<para>The standard only allows one procedure to be dropped per command.</para>
141210
</listitem>
142211
<listitem>
143-
<para>The <literal>IF EXISTS</literal> option</para>
212+
<para>The <literal>IF EXISTS</literal> option is an extension.</para>
144213
</listitem>
145214
<listitem>
146-
<para>The ability to specify argument modes and names</para>
215+
<para>The ability to specify argument modes and names is an
216+
extension, and the lookup rules differ when modes are given.</para>
147217
</listitem>
148218
</itemizedlist></para>
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</refsect1>

‎doc/src/sgml/ref/drop_routine.sgml

Lines changed: 36 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -30,15 +30,44 @@ DROP ROUTINE [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [ (
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<title>Description</title>
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3232
<para>
33-
<command>DROP ROUTINE</command> removes the definition ofan existing
34-
routine, which can be an aggregate function, a normal function, or a
35-
procedure. See
33+
<command>DROP ROUTINE</command> removes the definition ofone or more
34+
existing routines. The term <quote>routine</quote> includes
35+
aggregate functions, normal functions, and procedures. See
3636
under <xref linkend="sql-dropaggregate"/>, <xref linkend="sql-dropfunction"/>,
3737
and <xref linkend="sql-dropprocedure"/> for the description of the
3838
parameters, more examples, and further details.
3939
</para>
4040
</refsect1>
4141

42+
<refsect1 id="sql-droproutine-notes">
43+
<title>Notes</title>
44+
45+
<para>
46+
The lookup rules used by <command>DROP ROUTINE</command> are
47+
fundamentally the same as for <command>DROP PROCEDURE</command>; in
48+
particular, <command>DROP ROUTINE</command> shares that command's
49+
behavior of considering an argument list that has
50+
no <replaceable class="parameter">argmode</replaceable> markers to be
51+
possibly using the SQL standard's definition that <literal>OUT</literal>
52+
arguments are included in the list. (<command>DROP AGGREGATE</command>
53+
and <command>DROP FUNCTION</command> do not do that.)
54+
</para>
55+
56+
<para>
57+
In some cases where the same name is shared by routines of different
58+
kinds, it is possible for <command>DROP ROUTINE</command> to fail with
59+
an ambiguity error when a more specific command (<command>DROP
60+
FUNCTION</command>, etc.) would work. Specifying the argument type
61+
list more carefully will also resolve such problems.
62+
</para>
63+
64+
<para>
65+
These lookup rules are also used by other commands that
66+
act on existing routines, such as <command>ALTER ROUTINE</command>
67+
and <command>COMMENT ON ROUTINE</command>.
68+
</para>
69+
</refsect1>
70+
4271
<refsect1 id="sql-droproutine-examples">
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<title>Examples</title>
4473

@@ -64,13 +93,14 @@ DROP ROUTINE foo(integer);
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<para>The standard only allows one routine to be dropped per command.</para>
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</listitem>
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<listitem>
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<para>The <literal>IF EXISTS</literal> option</para>
96+
<para>The <literal>IF EXISTS</literal> option is an extension.</para>
6897
</listitem>
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<listitem>
70-
<para>The ability to specify argument modes and names</para>
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<para>The ability to specify argument modes and names is an
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extension, and the lookup rules differ when modes are given.</para>
71101
</listitem>
72102
<listitem>
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<para>Aggregate functions are an extension.</para>
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<para>User-definable aggregate functions are an extension.</para>
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</listitem>
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</itemizedlist></para>
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</refsect1>

‎doc/src/sgml/ref/security_label.sgml

Lines changed: 5 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -126,12 +126,11 @@ SECURITY LABEL [ FOR <replaceable class="parameter">provider</replaceable> ] ON
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argument: <literal>IN</literal>, <literal>OUT</literal>,
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<literal>INOUT</literal>, or <literal>VARIADIC</literal>.
128128
If omitted, the default is <literal>IN</literal>.
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Note that <command>SECURITY LABEL</command> does not actually pay any
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attention to <literal>OUT</literal> arguments for functions and
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aggregates (but not procedures), since only the input arguments are
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needed to determine the function's identity. So it is sufficient to
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list the <literal>IN</literal>, <literal>INOUT</literal>, and
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<literal>VARIADIC</literal> arguments for functions and aggregates.
129+
Note that <command>SECURITY LABEL</command> does not actually
130+
pay any attention to <literal>OUT</literal> arguments, since only the input
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arguments are needed to determine the function's identity.
132+
So it is sufficient to list the <literal>IN</literal>, <literal>INOUT</literal>,
133+
and <literal>VARIADIC</literal> arguments.
135134
</para>
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</listitem>
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</varlistentry>

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