Horton

Re: insensitive collations

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Daniel Verite <daniel@manitou-mail.org>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2019-01-10T07:49:48Z
Lists: pgsql-hackers 
On 09/01/2019 22:01, Daniel Verite wrote:
>> I don't see anything wrong here.  The collation says that both values
>> are equal, so which one is returned is implementation-dependent.
> Is it, but it's impractical if the product of seemingly the same GROUP BY
> flip-flops between its different valid results. If it can't be avoided, then
> okay. If it can be avoided at little cost, then it would be better to do it.

But there is no concept of which one of these is the preferred variant,
so I don't see how the system is supposed to pick one and then stick to
it across separate query invocations.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Collations with nondeterministic comparison

  2. Add support for collation attributes on older ICU versions

  3. Make type "name" collation-aware.

  4. Make collation-aware system catalog columns use "C" collation.

  5. Adjust string comparison so that only bitwise-equal strings are considered