Doc: Add note for running ANALYZE after ALTER TABLE ... SET EXPRESSION - Mailing list pgsql-hackers

Hi,

The documentation recommends running ANALYZE after the "ALTER TABLE ... SET DATA TYPE"
command since the statistics will become wrong after that.

That same thing can be applied to "ALTER TABLE ... SET EXPRESSION" commands,
but that is not described in the documentation, so I've attached a patch
to add this statement.


Regards,
Yugo Nagata