Fixed #10929 -- Added default argument to aggregates.

Thanks to Simon Charette and Adam Johnson for the reviews.

1 files changed, 44 insertions, 38 deletions

diff --git a/docs/ref/contrib/postgres/aggregates.txt b/docs/ref/contrib/postgres/aggregates.txt
index c309dcad14..61ec86fa44 100644
--- a/docs/ref/contrib/postgres/aggregates.txt
+++ b/docs/ref/contrib/postgres/aggregates.txt
@@ -19,8 +19,8 @@ module. They are described in more detail in the `PostgreSQL docs
 
 .. admonition:: Common aggregate options
 
-    All aggregates have the :ref:`filter <aggregate-filter>` keyword
-    argument.
+    All aggregates have the :ref:`filter <aggregate-filter>` keyword argument
+    and most also have the :ref:`default <aggregate-default>` keyword argument.
 
 General-purpose aggregation functions
 =====================================
@@ -28,9 +28,10 @@ General-purpose aggregation functions
 ``ArrayAgg``
 ------------
 
-.. class:: ArrayAgg(expression, distinct=False, filter=None, ordering=(), **extra)
+.. class:: ArrayAgg(expression, distinct=False, filter=None, default=None, ordering=(), **extra)
 
-    Returns a list of values, including nulls, concatenated into an array.
+    Returns a list of values, including nulls, concatenated into an array, or
+    ``default`` if there are no values.
 
     .. attribute:: distinct
 
@@ -54,26 +55,26 @@ General-purpose aggregation functions
 ``BitAnd``
 ----------
 
-.. class:: BitAnd(expression, filter=None, **extra)
+.. class:: BitAnd(expression, filter=None, default=None, **extra)
 
     Returns an ``int`` of the bitwise ``AND`` of all non-null input values, or
-    ``None`` if all values are null.
+    ``default`` if all values are null.
 
 ``BitOr``
 ---------
 
-.. class:: BitOr(expression, filter=None, **extra)
+.. class:: BitOr(expression, filter=None, default=None, **extra)
 
     Returns an ``int`` of the bitwise ``OR`` of all non-null input values, or
-    ``None`` if all values are null.
+    ``default`` if all values are null.
 
 ``BoolAnd``
 -----------
 
-.. class:: BoolAnd(expression, filter=None, **extra)
+.. class:: BoolAnd(expression, filter=None, default=None, **extra)
 
-    Returns ``True``, if all input values are true, ``None`` if all values are
-    null or if there are no values, otherwise ``False`` .
+    Returns ``True``, if all input values are true, ``default`` if all values
+    are null or if there are no values, otherwise ``False``.
 
     Usage example::
 
@@ -92,9 +93,9 @@ General-purpose aggregation functions
 ``BoolOr``
 ----------
 
-.. class:: BoolOr(expression, filter=None, **extra)
+.. class:: BoolOr(expression, filter=None, default=None, **extra)
 
-    Returns ``True`` if at least one input value is true, ``None`` if all
+    Returns ``True`` if at least one input value is true, ``default`` if all
     values are null or if there are no values, otherwise ``False``.
 
     Usage example::
@@ -114,9 +115,10 @@ General-purpose aggregation functions
 ``JSONBAgg``
 ------------
 
-.. class:: JSONBAgg(expressions, distinct=False, filter=None, ordering=(), **extra)
+.. class:: JSONBAgg(expressions, distinct=False, filter=None, default=None, ordering=(), **extra)
 
-    Returns the input values as a ``JSON`` array.
+    Returns the input values as a ``JSON`` array, or ``default`` if there are
+    no values.
 
     .. attribute:: distinct
 
@@ -139,10 +141,10 @@ General-purpose aggregation functions
 ``StringAgg``
 -------------
 
-.. class:: StringAgg(expression, delimiter, distinct=False, filter=None, ordering=())
+.. class:: StringAgg(expression, delimiter, distinct=False, filter=None, default=None, ordering=())
 
     Returns the input values concatenated into a string, separated by
-    the ``delimiter`` string.
+    the ``delimiter`` string, or ``default`` if there are no values.
 
     .. attribute:: delimiter
 
@@ -174,17 +176,17 @@ field or an expression returning a numeric data. Both are required.
 ``Corr``
 --------
 
-.. class:: Corr(y, x, filter=None)
+.. class:: Corr(y, x, filter=None, default=None)
 
-    Returns the correlation coefficient as a ``float``, or ``None`` if there
+    Returns the correlation coefficient as a ``float``, or ``default`` if there
     aren't any matching rows.
 
 ``CovarPop``
 ------------
 
-.. class:: CovarPop(y, x, sample=False, filter=None)
+.. class:: CovarPop(y, x, sample=False, filter=None, default=None)
 
-    Returns the population covariance as a ``float``, or ``None`` if there
+    Returns the population covariance as a ``float``, or ``default`` if there
     aren't any matching rows.
 
     Has one optional argument:
@@ -198,18 +200,18 @@ field or an expression returning a numeric data. Both are required.
 ``RegrAvgX``
 ------------
 
-.. class:: RegrAvgX(y, x, filter=None)
+.. class:: RegrAvgX(y, x, filter=None, default=None)
 
     Returns the average of the independent variable (``sum(x)/N``) as a
-    ``float``, or ``None`` if there aren't any matching rows.
+    ``float``, or ``default`` if there aren't any matching rows.
 
 ``RegrAvgY``
 ------------
 
-.. class:: RegrAvgY(y, x, filter=None)
+.. class:: RegrAvgY(y, x, filter=None, default=None)
 
     Returns the average of the dependent variable (``sum(y)/N``) as a
-    ``float``, or ``None`` if there aren't any matching rows.
+    ``float``, or ``default`` if there aren't any matching rows.
 
 ``RegrCount``
 -------------
@@ -219,56 +221,60 @@ field or an expression returning a numeric data. Both are required.
     Returns an ``int`` of the number of input rows in which both expressions
     are not null.
 
+    .. note::
+
+        The ``default`` argument is not supported.
+
 ``RegrIntercept``
 -----------------
 
-.. class:: RegrIntercept(y, x, filter=None)
+.. class:: RegrIntercept(y, x, filter=None, default=None)
 
     Returns the y-intercept of the least-squares-fit linear equation determined
-    by the ``(x, y)`` pairs as a ``float``, or ``None`` if there aren't any
+    by the ``(x, y)`` pairs as a ``float``, or ``default`` if there aren't any
     matching rows.
 
 ``RegrR2``
 ----------
 
-.. class:: RegrR2(y, x, filter=None)
+.. class:: RegrR2(y, x, filter=None, default=None)
 
     Returns the square of the correlation coefficient as a ``float``, or
-    ``None`` if there aren't any matching rows.
+    ``default`` if there aren't any matching rows.
 
 ``RegrSlope``
 -------------
 
-.. class:: RegrSlope(y, x, filter=None)
+.. class:: RegrSlope(y, x, filter=None, default=None)
 
     Returns the slope of the least-squares-fit linear equation determined
-    by the ``(x, y)`` pairs as a ``float``, or ``None`` if there aren't any
+    by the ``(x, y)`` pairs as a ``float``, or ``default`` if there aren't any
     matching rows.
 
 ``RegrSXX``
 -----------
 
-.. class:: RegrSXX(y, x, filter=None)
+.. class:: RegrSXX(y, x, filter=None, default=None)
 
     Returns ``sum(x^2) - sum(x)^2/N`` ("sum of squares" of the independent
-    variable) as a ``float``, or ``None`` if there aren't any matching rows.
+    variable) as a ``float``, or ``default`` if there aren't any matching rows.
 
 ``RegrSXY``
 -----------
 
-.. class:: RegrSXY(y, x, filter=None)
+.. class:: RegrSXY(y, x, filter=None, default=None)
 
     Returns ``sum(x*y) - sum(x) * sum(y)/N`` ("sum of products" of independent
-    times dependent variable) as a ``float``, or ``None`` if there aren't any
-    matching rows.
+    times dependent variable) as a ``float``, or ``default`` if there aren't
+    any matching rows.
 
 ``RegrSYY``
 -----------
 
-.. class:: RegrSYY(y, x, filter=None)
+.. class:: RegrSYY(y, x, filter=None, default=None)
 
     Returns ``sum(y^2) - sum(y)^2/N`` ("sum of squares" of the dependent
-    variable)  as a ``float``, or ``None`` if there aren't any matching rows.
+    variable) as a ``float``, or ``default`` if there aren't any matching rows.
 
 Usage examples
 ==============