Re: [PG19] Indexes from 18 miss rows after pg_upgrade

[shihao zhong]

Hi Jeff,

> Is that still just a release note, or does it demand something more?

I think it needs more. With LC_CTYPE C, text search changed too, not
only pg_trgm. In a builtin C.UTF-8 database:

    select to_tsvector('simple', 'foo—bar don’t naïve');
    18.6:   'don’t':2 'foo—bar':1 'naïve':3
    19rc1:  'bar':2 'don':3 'foo':1 'naïve':5 't':4

In my upgrade test, every text search and pg_trgm index in ICU and
builtin databases with LC_CTYPE C missed rows. Any accent or curly
quote is enough.

I did some history check and found fb1a18810f, the 18 notes said to reindex
all of them, so I think pg_upgrade should name the indexes, as the
patch does.

> Should that note be expanded?

Yes. Stems also changed for english, german, swedish, lithuanian,
french and norwegian.... The note may also need a cover extension like
fuzzystrmatch,  which changed in libc databases too.

Thanks,
Shihao