CLUSTER micro-doc-patch

Hello All,

Doing recently the CLUSTER operation with (SELECT .. ORDER BY ...) instead
of CLUSTER I realized that that operation requires the free space equal to
twice! the size of the table size :-( (which is unfortunately a serious
drawback of the SELECT method, comparing to the plain CLUSTER for
the large tables )...

So, I send the small doc-patch saying about the space requirement of the
cluster operation using SELECT ORDER BY.

Regards,
Sergey

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Sergey E. Koposov
Max Planck Institute for Astronomy/Sternberg Astronomical Institute
Tel: +49-6221-528-349
Web: http://lnfm1.sai.msu.ru/~math
E-mail: math@sai.msu.ru