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https://issues.apache.org/jira/browse/DERBY-731?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Dag H. Wanvik updated DERBY-731:
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Derby Categories: [Performance]
> org.apache.derby.impl.sql.compile.StringSlice is an inefficient way to do
> substring
> -----------------------------------------------------------------------------------
>
> Key: DERBY-731
> URL: https://issues.apache.org/jira/browse/DERBY-731
> Project: Derby
> Issue Type: Improvement
> Components: SQL
> Reporter: Daniel John Debrunner
> Assignee: Daniel John Debrunner
> Priority: Trivial
> Fix For: 10.2.1.6
>
>
> StringSlicer is a class that is basically implementing String.substring()
> with an optional trim in an inefficient manner.
> It creates a char array from the original string and uses this new array to
> create sub strings. This means one allocation
> and copy for the original char array and another allocation and copy for
> every subsequent slice operation.
> String.substring performs the same functionality but it can create
> sub-strings without the character array allocation
> and copy by re-using the character arrray hidden within the original string.
> I've been running tests with a additional code in StringSlicer that compares
> its output with that of String.substring with
> no differences. One minor annoyance is that StringSlicer uses an inclusive
> end offset while String.substring uses an
> exclusive end offset.
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