Re: text search changes vs. binary upgrade

On Tue, May 03, 2016 at 11:13:54PM -0400, Tom Lane wrote:
> Noah Misch <noah(at)leadboat(dot)com> writes:
> > Commit bb14050 said:
> > - change order for tsquery, so, users, who has a btree index over tsquery,
> > should reindex it
>
> We undid that in 1ec4c7c05, no?

Ah, looks that way.

> > Commit 61d66c4 may or may not warrant pg_upgrade treatment:
> > Fix support of digits in email/hostnames.
>
> The general theory about changes in text search parser and dictionary
> behavior has always been that a reindex is not required, because that does
> not invalidate the derived data in the same sort of way that changing,
> say, btree sort order of a datatype would. At worst, searches for the
> specifically affected words might fail to find relevant entries because
> to_tsvector now produces a different list of lexemes than before (and
> those new lexemes are not in the index, the old ones are). If the
> affected set of words is sufficiently large and relevant to her use-case,
> a user might judge that rebuilding derived tsvector data is worth her
> trouble. But I am dubious that pg_upgrade should issue guidance
> unconditionally telling people to do it. Most people probably aren't
> going to have any noticeable amount of data that's affected by this change.
>
> If we did worry about this for 61d66c4, then for example the unaccent
> changes would also be problematic, and probably the ispell changes too.
> I'm inclined to just group all those things in the release notes and
> provide text counseling users to think about how much those changes affect
> their full-text data and whether rebuilding derived tsvectors would be
> worth it.

Fair.