On 9/8/16 11:16 AM, Tom Lane wrote:
> This is a problem, if ICU won't guarantee cross-version compatibility,
> because it destroys the argument that moving to ICU would offer us
> collation behavior stability.
It would offer a significant upgrade over the current situation.
First, it offers stability inside the same version. Whereas glibc might
change a collation in a minor upgrade, ICU won't do that. And the
postgres binary is bound to a major version of ICU by the soname (which
changes with every major release). So this would avoid the situation
that a simple OS update could break collations.
Second, it offers a way to detect that something has changed. With
glibc, you don't know anything unless you read the source diffs. With
ICU, you can compare the collation version before and after and at least
tell the user that they need to refresh indexes or whatever.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services