Re: insensitive collations

On 30/01/2019 16:30, Daniel Verite wrote:
>     Peter Eisentraut wrote:
> 
>> Another patch. 

Another patch, with expanded documentation, more tests, and some code
cleanup.

> 
> +    <literal>ks</literal> key), in order for such such collations to act in
> a
> 
> s/such such/such/

fixed

> 
> +   <para>
> +    The pattern matching operators of all three kinds do not support
> +    nondeterministic collations.  If required, apply a different collation
> to
> +    the expression to work around this limitation.
> +   </para>
> 
> It's an important point of comparison between CI collations and
> contrib/citext, since the latter diverts a bunch of functions/operators
> to make them do case-insensitive pattern matching.
> The doc for citext explains the rationale for using it versus text,
> maybe it would need now to be expanded a bit with pros/cons of
> choosing citext versus non-deterministic collations.

possibly addressed by the expanded documentation

> The current patch doesn't alter a few string functions that could
> potentially implement collation-aware string search, such as
> replace(), strpos(), starts_with().
> ISTM that we should not let these functions ignore the collation: they
> ought to error out until we get their implementation to use the ICU
> collation-aware string search.

I have addressed that.  Many of these end up at the same one or two
low-level C function, so the checking just happens there.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
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