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Doc: update documentation for requirement of ORDER BY in GROUPS mode.

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Commit ff4f88916 adjusted the code to enforce the SQL spec's requirement
that a window using GROUPS mode must have an ORDER BY clause.  But I missed
that the documentation explicitly said you didn't have to have one.

Also minor wordsmithing in the window-function section of select.sgml.

Per Masahiko Sawada, though I didn't use his patch.
This commit is contained in:
Tom Lane 2018-07-12 11:10:24 -04:00
parent 8e599897ca
commit e0cd0ea4f9
2 changed files with 5 additions and 5 deletions
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6
doc/src/sgml/ref/select.sgml
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@ -901,8 +901,8 @@ EXCLUDE NO OTHERS
CURRENT ROW</literal>; it sets the frame to be all rows from the partition start
up through the current row's last <firstterm>peer</firstterm> (a row
that the window's <literal>ORDER BY</literal> clause considers
equivalent to the current row), or all rows if there
is no <literal>ORDER BY</literal>.
equivalent to the current row; all rows are peers if there
is no <literal>ORDER BY</literal>).
In general, <literal>UNBOUNDED PRECEDING</literal> means that the frame
starts with the first row of the partition, and similarly
<literal>UNBOUNDED FOLLOWING</literal> means that the frame ends with the last
@ -924,7 +924,7 @@ EXCLUDE NO OTHERS
is an integer indicating that the frame starts or ends that many peer
groups before or after the current row's peer group, where
a <firstterm>peer group</firstterm> is a group of rows that are
equivalent according to <literal>ORDER BY</literal>.
equivalent according to the window's <literal>ORDER BY</literal> clause.
In <literal>RANGE</literal> mode, use of
an <replaceable>offset</replaceable> option requires that there be
exactly one <literal>ORDER BY</literal> column in the window definition.

4
doc/src/sgml/syntax.sgml
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@ -1917,8 +1917,8 @@ EXCLUDE NO OTHERS
ends the specified number of <firstterm>peer groups</firstterm>
before or after the current row's peer group, where a peer group is a
set of rows that are equivalent in the <literal>ORDER BY</literal>
ordering. (If there is no <literal>ORDER BY</literal>, the whole
partition is one peer group.)
ordering. (There must be an <literal>ORDER BY</literal> clause
in the window definition to use <literal>GROUPS</literal> mode.)
</para>
</listitem>
<listitem>