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https://issues.apache.org/jira/browse/DERBY-6227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14037180#comment-14037180
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ASF subversion and git services commented on DERBY-6227:
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Commit 1603793 from [~knutanders] in branch 'code/trunk'
[ https://svn.apache.org/r1603793 ]
DERBY-6227: Distinct aggregates don't work well with territory-based collation
Make the duplicate elimination use the DataValueDescriptors directly instead
of converting the values to String objects first. This ensures that the
collation rules of the database are used to compare the values, and those
rules may be different from those used by String.equals().
> 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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