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https://issues.apache.org/jira/browse/DERBY-3854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12627048#action_12627048
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Daniel John Debrunner commented on DERBY-3854:
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> (1) all the characters before the wildcard map to exactly one collation
> element,
Need to add 'each' at the end, right, just to be clear?
Though I maybe having trouble understanding what this is trying to say exactly.
All single characters will map to a single collation element by themselves, so
I think it's really trying to say that none of the sequence of characters in
the prefix combine into a single collation element.???
> col < 'abcde\uFFFF'
\uFFFF is incorrect since it is not a valid character and the numeric codepoint
of the character is not what the index is using for ordering. You really need
col < 'abcdf'
where 'f' is the character determined from a collation element value than is
greater than the one for 'e'
> Implement LIKE transformations and optimizations for databases using
> territory-based collations
> -----------------------------------------------------------------------------------------------
>
> Key: DERBY-3854
> URL: https://issues.apache.org/jira/browse/DERBY-3854
> Project: Derby
> Issue Type: Improvement
> Affects Versions: 10.3.3.0, 10.4.1.3, 10.5.0.0
> Reporter: Rick Hillegas
>
> The LIKE transformations and optimizations are disabled when using a database
> with a territory-based collation. See the following email thread:
> http://www.nabble.com/territory-based-collations-and-optimizations-for-the-LIKE-operator-td19111725.html#a19111725
> That thread, in turn, refers to DERBY-1478. It would be nice if we did not
> have to perform full table scans for LIKE queries in databases with
> territory-based collations.
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