Re: Add parallelism and glibc dependent only options to reindexdb

    Julien Rouhaud wrote:

> > I think you'd be better off to define and document this as "reindex
> > only collation-sensitive indexes", without any particular reference
> > to a reason why somebody might want to do that.
>
> We should still document that indexes based on ICU would be exluded?

But why exclude them?
As a data point, in the last 5 years, the en_US collation in ICU
had 7 different versions (across 11 major versions of ICU):

ICU    Unicode en_US

54.1    7.0    137.56
55.1    7.0    153.56
56.1    8.0    153.64
57.1    8.0    153.64
58.2    9.0    153.72
59.1    9.0    153.72
60.2    10.0    153.80
61.1    10.0    153.80
62.1    11.0    153.88
63.2    11.0    153.88
64.2    12.1    153.97

The rightmost column corresponds to pg_collation.collversion
in Postgres.
Each time there's a new Unicode version, it seems
all collation versions are bumped. And there's a new Unicode
version pretty much every year these days.
Based on this, most ICU upgrades in practice would require reindexing
affected indexes.


Best regards,
--
Daniel Vérité
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