| From: | Peter Geoghegan <pg(at)bowt(dot)ie> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: strcmp() tie-breaker for identical ICU-collated strings |
| Date: | 2017-07-11 01:44:01 |
| Message-ID: | CAH2-Wz=KryJQHCGhGpTfthDcxLEvbszMGsSan=gYBHs74DXicg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Jun 9, 2017 at 11:09 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> Isn't that what strxfrm() is?
>
> Yeah, just with bugs. If ICU has a non-buggy equivalent, then we can
> make this work.
I agree that it probably isn't worth using strxfrm() again, simply
because the glibc implementation is buggy, and glibc as a project is
not at all concerned about how badly that would affect PostgreSQL.
I would like to point out on this thread that the strcmp() tie-breaker
is also a big blocker to implementing normalized keys in B-Tree
indexes (at least, if you want to get them for collated text, which I
think you really need to make the implementation effort worth it).
This is something that is discussed in a section on the normalized
keys wiki page I created recently [1].
[1] https://wiki.postgresql.org/wiki/Key_normalization#ICU.2C_text_equality_semantics.2C_and_hashing
--
Peter Geoghegan
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