Re: pg_upgrade fails with missing FTS resources

On Fri, Jun 15, 2012 at 10:27:59PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > On Fri, Jun 15, 2012 at 04:15:57PM +0100, Daniele Varrazzo wrote:
> >> pg_upgrade fails on missing FTS dictionaries requiring external files.
> >> --check fails to detect the incompatibility.
>
> > Sure, we can test for that.  What system column stores these file names?
>
> Trying to check that on the basis of the system catalog entries seems
> quite hopeless.  What's in the catalogs is essentially what appears
> in the CREATE command, ie
>
> dictfile = 'italian_ispell', afffile = 'italian_ispell', stopwords = 'italian_ispell'
>
> The dictionary template knows which of these options are file names and
> which are not, and what filename extension to apply to each option that
> is a file name; but you don't.
>
> The closest that I think pg_upgrade could reasonably come is to compare
> the contents of the old and new installations' tsearch_data/
> directories, and complain about any files present in the former and not
> the latter.  However, that method seems fraught with opportunities for
> false positives: in particular you might complain about some file that
> was in the old installation but not actually referenced by any text
> search catalog entry.
>
> In the end I'm not sure it's worth it.  There are any number of ways
> that the restore step can fail, and it's impossible for pg_upgrade
> to pre-check for all of them.

Agreed.  Not worth it.  If it is reported again, we can document this
requirement.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +