Horton

Re: Collation versioning

Douglas Doole <dougdoole@gmail.com>

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From: Douglas Doole <dougdoole@gmail.com>
To: Andrew Gierth <andrew@tao11.riddles.org.uk>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Christoph Berg <myon@debian.org>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-09-16T19:00:52Z
Lists: pgsql-hackers 
Oh good. I'd missed that detail. So that eases the RI constraint concern.
(In my previous job, we wanted case/accent insensitive collations, so equal
did not mean binary equal which added a whole extra level of fun.)

On Sun, Sep 16, 2018 at 11:39 AM Andrew Gierth <andrew@tao11.riddles.org.uk>
wrote:

> >>>>> "Douglas" == Douglas Doole <dougdoole@gmail.com> writes:
>
>  Douglas> And constraints problems are even easier than triggers.
>  Douglas> Consider a database with complex BI rules that are implemented
>  Douglas> through triggers that fire when values are/are not equal. If
>  Douglas> the equality of strings change, there could be bad data
>  Douglas> throughout the tables.
>
> Perhaps fortunately, collation changes cannot (in PG) affect the
> equality or non-equality of strings (at least of text/varchar/char
> types, citext is a different matter). For the builtin string types, PG
> follows the rule that if the collation calls the values equal, they are
> ordered secondarily in codepoint order; only byte-identical values can
> actually be equal (we need this in order for hashing to work in the
> absence of a strxfrm implementation that we can trust).
>
> (This is the same rule used for string comparisons in Perl.)
>
> --
> Andrew (irc:RhodiumToad)
>

Commits

  1. Doc: Document known problem with Windows collation versions.

  2. Add collation versions for FreeBSD.

  3. Tolerate version lookup failure for old style Windows locale names.

  4. Track collation versions for indexes.

  5. Add pg_depend.refobjversion.

  6. Remove pg_collation.collversion.

  7. Fix the MSVC build for versions 2015 and later.

  8. Add collation versions for Windows.

  9. Implement type regcollation

  10. Use libc version as a collation version on glibc systems.

  11. Make type "name" collation-aware.