Re: Collation versioning

>>>>> "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)