[Cubicweb] unique constraint on unlimited String attribute

Julien Cristau julien at cristau.org
Thu Jun 16 15:03:27 CEST 2016

On Thu, Jun 16, 2016 at 14:25:50 +0200, Sylvain Thénault wrote:

> Hi there,
> a while ago I added a unique constraint on cwuri in cubicweb. I've just
> discovered today that it has been removed by 1ee631aedf2f. So I'm wondering: is

This doesn't seem to be the changeset you're talking about, but rather
its child, 48e54aabcd5544945938092f7cf1d39f71b64fb2.

> it really a bad habit to add UNIQUE on unlimited string? I remember being
> advised to never set size constraint on string on postgres for instance...
Indices on unlimited string columns are not supported by sql server, at
least, and in general it seems questionable from a design and
performance pov to want to search on such a field (except using full
text search).

I guess one option is to have an extra computed column with a (fixed
size) hash of your nvarchar(max) column, and index *that*, but
reconsidering either the index or the lack of size limit might be


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