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Commited3dc22

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Doc: clarify description of degenerate NATURAL joins.
Claiming that NATURAL JOIN is equivalent to CROSS JOIN when there areno common column names is only strictly correct if it's an inner join;you can't say e.g. CROSS LEFT JOIN. Better to explain it as meaningJOIN ON TRUE, instead. Per a suggestion from David Johnston.Discussion:https://postgr.es/m/CAKFQuwb+mYszQhDS9f_dqRrk1=Pe-S6D=XMkAXcDf4ykKPmgKQ@mail.gmail.com
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‎doc/src/sgml/queries.sgml

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@@ -391,8 +391,8 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
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consisting of all column names that appear in both
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input tables. As with <literal>USING</>, these columns appear
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only once in the output table. If there are no common
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column names, <literal>NATURAL</literal> behaves like
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<literal>CROSSJOIN</literal>.
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column names, <literal>NATURAL JOIN</literal> behaves like
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<literal>JOIN ... ON TRUE</literal>, producing a cross-product join.
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</para>
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<note>

‎doc/src/sgml/ref/select.sgml

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@@ -603,9 +603,12 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ]
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<varlistentry>
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<term><literal>NATURAL</literal></term>
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<listitem>
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<para><literal>NATURAL</literal> is shorthand for a
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<para>
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<literal>NATURAL</literal> is shorthand for a
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<literal>USING</> list that mentions all columns in the two
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tables that have the same names.
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tables that have matching names. If there are no common
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column names, <literal>NATURAL</literal> is equivalent
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to <literal>ON TRUE</>.
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</para>
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</listitem>
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</varlistentry>

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