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Support the syntax

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CREATE AGGREGATE aggname (input_type) (parameter_list)
along with the old syntax where the input type was named in the parameter
list.  This fits more naturally with the way that the aggregate is identified
in DROP AGGREGATE and other utility commands; furthermore it has a natural
extension to handle multiple-input aggregates, where the basetype-parameter
method would get ugly.  In fact, this commit fixes the grammar and all the
utility commands to support multiple-input aggregates; but DefineAggregate
rejects it because the executor isn't fixed yet.
I didn't do anything about treating agg(*) as a zero-input aggregate instead
of artificially making it a one-input aggregate, but that should be considered
in combination with supporting multi-input aggregates.
This commit is contained in:
Tom Lane
2006-04-15 17:45:46 +00:00
parent ebd5257d49
commit 3651a3e6fb
17 changed files with 395 additions and 351 deletions
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37
doc/src/sgml/ref/create_aggregate.sgml
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@@ -1,5 +1,5 @@
<!--
$PostgreSQL: pgsql/doc/src/sgml/ref/create_aggregate.sgml,v 1.33 2005/11/04 23:14:02 petere Exp $
$PostgreSQL: pgsql/doc/src/sgml/ref/create_aggregate.sgml,v 1.34 2006/04/15 17:45:18 tgl Exp $
PostgreSQL documentation
-->
@@ -20,8 +20,18 @@ PostgreSQL documentation
<refsynopsisdiv>
<synopsis>
CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> ( <replaceable class="PARAMETER">input_data_type</replaceable> ) (
SFUNC = <replaceable class="PARAMETER">sfunc</replaceable>,
STYPE = <replaceable class="PARAMETER">state_data_type</replaceable>
[ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
[ , INITCOND = <replaceable class="PARAMETER">initial_condition</replaceable> ]
[ , SORTOP = <replaceable class="PARAMETER">sort_operator</replaceable> ]
)
or the old syntax
CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
BASETYPE = <replaceable class="PARAMETER">input_data_type</replaceable>,
BASETYPE = <replaceable class="PARAMETER">base_type</replaceable>,
SFUNC = <replaceable class="PARAMETER">sfunc</replaceable>,
STYPE = <replaceable class="PARAMETER">state_data_type</replaceable>
[ , FINALFUNC = <replaceable class="PARAMETER">ffunc</replaceable> ]
@@ -87,7 +97,7 @@ CREATE AGGREGATE <replaceable class="PARAMETER">name</replaceable> (
<para>
An aggregate function may provide an initial condition,
that is, an initial value for the internal state value.
This is specified and stored in the database as a column of type
This is specified and stored in the database as a value of type
<type>text</type>, but it must be a valid external representation
of a constant of the state value data type. If it is not supplied
then the state value starts out null.
@@ -146,8 +156,9 @@ SELECT col FROM tab ORDER BY col USING sortop LIMIT 1;
Ordinarily, a data type's <literal>&lt;</> operator is the proper sort
operator for <function>MIN</>, and <literal>&gt;</> is the proper sort
operator for <function>MAX</>. Note that the optimization will never
actually take effect unless the specified operator is the <quote>less than</quote> or
<quote>greater than</quote> strategy member of a B-tree index operator class.
actually take effect unless the specified operator is the <quote>less
than</quote> or <quote>greater than</quote> strategy member of a B-tree
index operator class.
</para>
</refsect1>
@@ -170,13 +181,27 @@ SELECT col FROM tab ORDER BY col USING sortop LIMIT 1;
<listitem>
<para>
The input data type on which this aggregate function operates.
This can be specified as <literal>"ANY"</> for an aggregate that
This can be specified as <literal>*</> for an aggregate that
does not examine its input values (an example is
<function>count(*)</function>).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">base_type</replaceable></term>
<listitem>
<para>
In the old syntax for <command>CREATE AGGREGATE</>, the input data type
is specified by a <literal>basetype</> parameter rather than being
written next to the aggregate name. Note that this syntax allows
only one input parameter. To define an aggregate that does not examine
its input values, specify the <literal>basetype</> as
<literal>"ANY"</> (not <literal>*</>).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">sfunc</replaceable></term>
<listitem>