Re: Case Insensitive Comparison with Postgres 12

On 10/9/2019 12:34 AM, Laurenz Albe wrote:
> Igal Sapir wrote:
>> I am trying to test a simple case insensitive comparison.  Most likely the
>> collation that I chose is wrong, but I'm not sure how to choose the correct
>> one (for English/US?).  Here is my snippet:
>>
>> create collation case_insensitive(
>>      provider=icu, locale='en-US-x-icu', deterministic=false
>> );
>> select 'Abc' = 'abc' collate case_insensitive;
>>
>> I expected true but am getting false.
>>
>> Any thoughts?
> Yes, the LOCALE is wrong. Use
>
> create collation case_insensitive (
>     provider=icu, locale='en-US-u-ks-level2', deterministic=false
> );
>
> The name of the locale defines it.
>
> My blog post can give a simple introduction:
> https://www.cybertec-postgresql.com/en/icu-collations-against-glibc-2-28-data-corruption/

Thank you all for replying.  I tried to use the locale suggested by both 
Laurenz and Pavel, en-US-u-ks-level2, but I'm still getting false for a 
simple comparison of 'Abc' = 'abc'.  I tried the locale both as a 
'string' and as an "identifier":

 > select version();

version |
-------------------------------------------------------------------------------------------------------|
PostgreSQL 12.0 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 
20150623 (Red Hat 4.8.5-39), 64-bit|

 > drop collation if exists case_insensitive;

 > create collation case_insensitive (
    provider=icu, locale="en-US-u-ks-level2", deterministic=false
);

 > select 'Abc' = 'abc' collate case_insensitive as is_equal;

is_equal|
--------|
false   |

What am I doing wrong here?

Thanks,

Igal