pgsql: Add: > > * Consider decreasing the amount of memory used by

Log Message:
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Add:

* Consider decreasing the amount of memory used by PrivateRefCount

http://archives.postgresql.org/pgsql-hackers/2006-11/msg00797.php
http://archives.postgresql.org/pgsql-hackers/2007-01/msg00752.php

Modified Files:
--------------
pgsql/doc:
TODO (r1.2114 -> r1.2115)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/TODO.diff?r1=1.2114&r2=1.2115)
pgsql/doc/src/FAQ:
TODO.html (r1.615 -> r1.616)
(http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/FAQ/TODO.html.diff?r1=1.615&r2=1.616)