Re: pg_migrator issue with contrib

I wrote:
> * pg_buffercache has changed the view pg_buffercache, which is
> definitely going to be a migration issue.  Need to test whether
> it represents a crash risk if the old definition is migrated.

I checked this, and there is not a crash risk: the function successfully
creates its result tuplestore, and then the main executor notices it's
not compatible with the old view.  So you get

regression=# select * from pg_buffercache;
ERROR:  function return row and query-specified return row do not match
DETAIL:  Returned row contains 8 attributes, but query expects 7.

You can fix it by dropping and recreating the view (eg, run the module's
uninstall and then install scripts).  I suppose that might be a bit
annoying if you've built additional views atop this one, but overall
it doesn't sound too bad.

So I don't plan to do anything about this module.  Still working on
the others.
        regards, tom lane