Doc: clarify description of degenerate NATURAL joins.

Tom Lane <tgl@sss.pgh.pa.us>

Commit: ed3dc224e5aabd3cb0a5c348107f973fe5b10b0d
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date: 2017-07-20T16:41:26Z
Releases: 10.0
Doc: clarify description of degenerate NATURAL joins.

Claiming that NATURAL JOIN is equivalent to CROSS JOIN when there are
no 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 meaning
JOIN ON TRUE, instead.  Per a suggestion from David Johnston.

Discussion: https://postgr.es/m/CAKFQuwb+mYszQhDS9f_dqRrk1=Pe-S6D=XMkAXcDf4ykKPmgKQ@mail.gmail.com

Files

PathChange+/−
doc/src/sgml/queries.sgml modified +2 −2
doc/src/sgml/ref/select.sgml modified +5 −2

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