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Re: Reverse-sort indexes and NULLS FIRST/LAST sorting

From: Heikki Linnakangas <heikki(at)enterprisedb(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgreSQL(dot)org
Subject: Re: Reverse-sort indexes and NULLS FIRST/LAST sorting
Date: 2007-01-02 15:12:18
Message-ID: 459A7652.3030700@enterprisedb.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Tom Lane wrote:
> Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
>> I'd like to see this implemented with more general collation support in 
>> mind.
> 
> I'm really not prepared to buy into that, simply because it puts ICU or
> some equivalent large chunk of new code into the critical path to finish
> what I'm doing.  ...

Yeah, I didn't mean doing that right now. Just to keep it in mind so 
that what we do now fits in nicely with it in the future.

>> The NULLS FIRST/LAST support, as well as ascending and descending 
>> orderings would be special cases of the general collation and collation 
>> conversion machinery.
> 
> That seems like a bad idea, because nulls first/last and asc/desc
> ordering are valid concepts for all btree-indexable datatypes, whereas
> collation is only meaningful for text.  Besides, that approach just
> moves the bloat over from too-many-opclasses to too-many-collations; do
> we really want to need four collation objects for each basic collation?

Hmm, I guess we don't.

-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com

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