[jira] [Commented] (DERBY-6227) Distinct aggregates don't work well with territory-based collation

["Dag H. Wanvik (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-6227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14036075#comment-14036075 ] 

Dag H. Wanvik commented on DERBY-6227:
--------------------------------------

Looks like a good patch to me. Makes me wonder whether we have other places in the execution machinery that uses plain Strings instead of DVDs.. Thanks for adding that comment caveat. +1


> Distinct aggregates don't work well with territory-based collation
> ------------------------------------------------------------------
>
>                 Key: DERBY-6227
>                 URL: https://issues.apache.org/jira/browse/DERBY-6227
>             Project: Derby
>          Issue Type: Bug
>          Components: SQL
>    Affects Versions: 10.6.1.0, 10.6.2.1, 10.7.1.1, 10.8.1.2, 10.8.2.2, 10.8.3.0, 10.9.1.0, 10.10.1.1
>            Reporter: Knut Anders Hatlen
>            Assignee: Knut Anders Hatlen
>              Labels: derby_triage10_11
>         Attachments: d6227-1a.diff
>
>
>  When working on DERBY-5840, I noticed that GroupedAggregateResultSet would do duplicate elimination by comparing the java.lang.String representation of the values. With territory-based collation, it is possible that two values that have different java.lang.String representation should be considered duplicates, and this logic will produce incorrect results.
> Example:
> ij version 10.10
> ij> connect 'jdbc:derby:memory:db;territory=en_US;collation=TERRITORY_BASED:PRIMARY;create=true';
> ij> create table t(i int, s varchar(10));
> 0 rows inserted/updated/deleted
> ij> insert into t values (1, 'a'), (1, 'a'), (2, 'b'), (2, 'B'), (3, 'a'), (3, 'A'), (3, 'b'), (3, 'B'), (3, 'c');
> 9 rows inserted/updated/deleted
> ij> select distinct s from t;
> S         
> ----------
> b         
> a         
> c         
> 3 rows selected
> ij> select i, count(distinct s) from t group by i;
> I          |2          
> -----------------------
> 1          |1          
> 2          |2          
> 3          |5          
> 3 rows selected
> I would have expected the last query to return
> (1, 1)
> (2, 1)
> (3, 3)



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