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Clean up to ensure tag completion as required by the newest versions
of Norm's Modular Style Sheets and jade/docbook. From Vince Vielhaber <vev@michvhf.com>.
This commit is contained in:
Thomas G. Lockhart
@@ -13,6 +13,7 @@
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<REFPURPOSE>
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Defines a new aggregate function
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</REFPURPOSE>
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</refnamediv>
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<REFSYNOPSISDIV>
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<REFSYNOPSISDIVINFO>
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<DATE>1998-09-09</DATE>
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@@ -150,11 +151,11 @@ The initial value for the first transition function argument.
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The initial value for the second transition function argument.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</varlistentry>
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</variablelist>
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</para>
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</REFSECT2>
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<REFSECT2 ID="R2-SQL-CREATEAGGREGATE-2">
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<REFSECT2INFO>
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<DATE>1998-09-09</DATE>
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@@ -163,20 +164,23 @@ The initial value for the second transition function argument.
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Outputs
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</TITLE>
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<PARA>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue>CREATE</ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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Message returned if the command completes successfully.
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</VARIABLELIST>
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<VARIABLELIST>
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<VARLISTENTRY>
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<TERM>
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<ReturnValue>CREATE</ReturnValue>
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</TERM>
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<LISTITEM>
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<PARA>
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Message returned if the command completes successfully.
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</para>
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</listitem>
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</varlistentry>
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</VARIABLELIST>
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</para>
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</REFSECT2>
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</REFSYNOPSISDIV>
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<REFSECT1 ID="R1-SQL-CREATEAGGREGATE-1">
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<REFSECT1INFO>
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<DATE>1998-09-09</DATE>
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@@ -184,80 +188,80 @@ The initial value for the second transition function argument.
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<TITLE>
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Description
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</TITLE>
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<para>
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<command>CREATE AGGREGATE</command>
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allows a user or programmer to extend <productname>Postgres</productname>
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functionality by defining new aggregate functions. Some aggregate functions
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for base types such as <function>min(int4)</function>
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and <function>avg(float8)</function> are already provided in the base
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distribution. If one defines new types or needs an aggregate function not
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already provided then <command>CREATE AGGREGATE</command>
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can be used to provide the desired features.
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<para>
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<command>CREATE AGGREGATE</command>
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allows a user or programmer to extend <productname>Postgres</productname>
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functionality by defining new aggregate functions. Some aggregate functions
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for base types such as <function>min(int4)</function>
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and <function>avg(float8)</function> are already provided in the base
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distribution. If one defines new types or needs an aggregate function not
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already provided then <command>CREATE AGGREGATE</command>
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can be used to provide the desired features.
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</para>
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<PARA>
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An aggregate function can require up to three functions, two
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state transition functions,
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>
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and <REPLACEABLE CLASS="PARAMETER">sfunc2</REPLACEABLE>:
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<programlisting>
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>( internal-state1, next-data_item ) ---> next-internal-state1
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<REPLACEABLE CLASS="PARAMETER">sfunc2</REPLACEABLE>( internal-state2 ) ---> next-internal-state2
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</programlisting>
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>
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and <REPLACEABLE CLASS="PARAMETER">sfunc2</REPLACEABLE>:
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<programlisting>
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>( internal-state1, next-data_item ) ---> next-internal-state1
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<REPLACEABLE CLASS="PARAMETER">sfunc2</REPLACEABLE>( internal-state2 ) ---> next-internal-state2
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</programlisting>
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and a final calculation function,
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<REPLACEABLE CLASS="PARAMETER">ffunc</REPLACEABLE>:
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<programlisting>
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<REPLACEABLE CLASS="PARAMETER">ffunc</REPLACEABLE>(internal-state1, internal-state2) ---> aggregate-value
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</programlisting>
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<para>
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<productname>Postgres</productname> creates up to two temporary variables
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(referred to here as <REPLACEABLE CLASS="PARAMETER">temp1</REPLACEABLE>
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and <REPLACEABLE CLASS="PARAMETER">temp2</REPLACEABLE>)
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to hold intermediate results used as arguments to the transition functions.
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<para>
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<REPLACEABLE CLASS="PARAMETER">ffunc</REPLACEABLE>:
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<programlisting>
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<REPLACEABLE CLASS="PARAMETER">ffunc</REPLACEABLE>(internal-state1, internal-state2) ---> aggregate-value
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</programlisting>
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</para>
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<para>
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<productname>Postgres</productname> creates up to two temporary variables
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(referred to here as <REPLACEABLE CLASS="PARAMETER">temp1</REPLACEABLE>
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and <REPLACEABLE CLASS="PARAMETER">temp2</REPLACEABLE>)
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to hold intermediate results used as arguments to the transition functions.
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</para>
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<para>
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These transition functions are required to have the following properties:
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<itemizedlist>
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<listitem>
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<para>
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The arguments to
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>
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must be
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<REPLACEABLE CLASS="PARAMETER">temp1</REPLACEABLE>
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of type
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<REPLACEABLE CLASS="PARAMETER">sfunc1_return_type</REPLACEABLE>
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and
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<REPLACEABLE CLASS="PARAMETER">column_value</REPLACEABLE>
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of type <REPLACEABLE CLASS="PARAMETER">data_type</REPLACEABLE>.
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The return value must be of type
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<REPLACEABLE CLASS="PARAMETER">sfunc1_return_type</REPLACEABLE>
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and will be used as the first argument in the next call to
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>.
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>
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must be
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<REPLACEABLE CLASS="PARAMETER">temp1</REPLACEABLE>
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of type
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<REPLACEABLE CLASS="PARAMETER">sfunc1_return_type</REPLACEABLE>
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and
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<REPLACEABLE CLASS="PARAMETER">column_value</REPLACEABLE>
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of type <REPLACEABLE CLASS="PARAMETER">data_type</REPLACEABLE>.
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The return value must be of type
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<REPLACEABLE CLASS="PARAMETER">sfunc1_return_type</REPLACEABLE>
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and will be used as the first argument in the next call to
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<REPLACEABLE CLASS="PARAMETER">sfunc1</REPLACEABLE>.
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</para>
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</listitem>
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<listitem>
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<para>
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The argument and return value of
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<REPLACEABLE CLASS="PARAMETER">sfunc2</REPLACEABLE>
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must be
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<REPLACEABLE CLASS="PARAMETER">temp2</REPLACEABLE>
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of type
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<REPLACEABLE CLASS="PARAMETER">sfunc2_return_type</REPLACEABLE>.
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<REPLACEABLE CLASS="PARAMETER">sfunc2</REPLACEABLE>
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must be
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<REPLACEABLE CLASS="PARAMETER">temp2</REPLACEABLE>
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of type
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<REPLACEABLE CLASS="PARAMETER">sfunc2_return_type</REPLACEABLE>.
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</para>
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</listitem>
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<listitem>
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<para>
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The arguments to the final-calculation-function
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must be
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<REPLACEABLE CLASS="PARAMETER">temp1</REPLACEABLE>
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and
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<REPLACEABLE CLASS="PARAMETER">temp2</REPLACEABLE>
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and its return value must
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<REPLACEABLE CLASS="PARAMETER">temp1</REPLACEABLE>
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and
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<REPLACEABLE CLASS="PARAMETER">temp2</REPLACEABLE>
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and its return value must
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be a <productname>Postgres</productname>
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base type (not necessarily
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<REPLACEABLE CLASS="PARAMETER">data_type</REPLACEABLE>
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which had been specified for BASETYPE).
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base type (not necessarily
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<REPLACEABLE CLASS="PARAMETER">data_type</REPLACEABLE>
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which had been specified for BASETYPE).
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</para>
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</listitem>
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<listitem>
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@@ -269,7 +273,7 @@ which had been specified for BASETYPE).
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</listitem>
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</itemizedlist>
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</PARA>
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<para>
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An aggregate function may also require one or two initial conditions,
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one for
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@@ -301,41 +305,42 @@ which had been specified for BASETYPE).
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well as a FINALFUNC (a division function) to produce its
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answer. In any case, at least one state function must be
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defined, and any SFUNC2 must have a corresponding INITCOND2.
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</para>
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</para>
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</REFSECT2>
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</refsect1>
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<REFSECT1 ID="R1-SQL-CREATEAGGREGATE-2">
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<TITLE>
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Usage
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</TITLE>
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<PARA>
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Refer to the chapter on aggregate functions
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in the <citetitle>PostgreSQL Programmer's Guide</citetitle>
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on aggregate functions for
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complete examples of usage.
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Refer to the chapter on aggregate functions
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in the <citetitle>PostgreSQL Programmer's Guide</citetitle>
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on aggregate functions for
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complete examples of usage.
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</para>
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</REFSECT1>
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<REFSECT1 ID="R1-SQL-CREATEAGGREGATE-3">
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<TITLE>
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Compatibility
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</TITLE>
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<PARA>
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<REFSECT2 ID="R2-SQL-CREATEAGGREGATE-4">
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<REFSECT2INFO>
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<DATE>1998-09-09</DATE>
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<DATE>1998-09-09</DATE>
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</REFSECT2INFO>
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<TITLE>
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SQL92
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</TITLE>
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<PARA>
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<command>CREATE AGGREGATE</command>
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is a <productname>Postgres</productname> language extension.
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is a <productname>Postgres</productname> language extension.
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There is no <command>CREATE AGGREGATE</command> in SQL92.
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</PARA>
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</refsect2>
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</refsect1>
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</REFENTRY>
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<!-- Keep this comment at the end of the file
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