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https://issues.apache.org/jira/browse/DERBY-5959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13482379#comment-13482379
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Knut Anders Hatlen commented on DERBY-5959:
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Since Derby only supports RuleBasedCollator, one solution could be to store the
rules (RuleBasedCollator.getRules()) at database-creation time, and use that
value to reconstruct the collator on subsequent boots (using the
RuleBasedCollator(String) constructor). This would also allow use of a database
with territory-based collation on a platform that doesn't support the specific
locale, as long as it was available on the platform where the database was
created.
The downside of such an approach is that the database users won't automatically
get the benefit of fixes in the collation rules (such as the above mentioned
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6755060 bug) when upgrading
the JRE.
Another approach may be to instruct users to drop and recreate all indexes that
contain CHAR/VARCHAR columns when switching to another JRE, but that may be
impractical. Also, if the user fails to do this, inconsistencies may sneak into
the database.
> Territory-based collation is not robust against changes in the collation rules
> ------------------------------------------------------------------------------
>
> Key: DERBY-5959
> URL: https://issues.apache.org/jira/browse/DERBY-5959
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.10.0.0
> Reporter: Knut Anders Hatlen
>
> When accessing a database with territory-based collation, Derby will use the
> collation rules of the collator returned by
> Collator.getInstance(databaseLocale). However, there is no guarantee that
> those rules are consistent across different JVM vendors and versions. This
> means that the ordering could vary, and inconsistencies could sneak into the
> indexes.
> One example is that Oracle's JDK changed the collation rules for Turkish
> between Java 5 and Java 6, so if you run the following script
> connect
> 'jdbc:derby:memory:db;territory=tr_TR;collation=TERRITORY_BASED;create=true';
> create table t(c char(2));
> insert into t values 'ıa', 'Ia', 'ia', 'İa', 'ıb', 'Ib', 'ib', 'İb';
> select * from t order by c;
> you'll get different results on Java 5 and on Java 6 and later.
> Java 5 will order the results like this:
> ij> select * from t order by c;
> C
> ----
> ıa
> Ia
> ia
> İa
> ıb
> Ib
> ib
> İb
> 8 rows selected
> Java 6 and later order them like this like this:
> ij> select * from t order by c;
> C
> ----
> ıa
> Ia
> ıb
> Ib
> ia
> İa
> ib
> İb
> 8 rows selected
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