Re: Removing SORTFUNC_LT/REVLT - Mailing list pgsql-hackers

From Greg Stark
Subject Re: Removing SORTFUNC_LT/REVLT
Date
Msg-id 87bqyx95ac.fsf@stark.xeocode.com
Whole thread Raw
In response to Re: Removing SORTFUNC_LT/REVLT  (Martijn van Oosterhout <kleptog@svana.org>)
Responses Re: Removing SORTFUNC_LT/REVLT  (Martijn van Oosterhout <kleptog@svana.org>)
List pgsql-hackers
Martijn van Oosterhout <kleptog@svana.org> writes:

> Yet hashing is also a property of the collation, not the type. The same
> string in different locales would hash differently.

I think this is a mistake -- the same mistake that got us into trouble with
Turkish.

Hashing depends on the concept of equality which is integral to the type. Two
things are either the same or they aren't, and that can't change based on
context.

Specifically in the case of strings, two strings should only be considered
"equal" if they consist of the exact same series of characters. (That is, they
could be encoded differently but they have to encode the same actual
characters.) That they happen to sort equally compared to all other strings
doesn't mean that they're equal.

-- 
greg



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