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From "Dag H. Wanvik (JIRA)" <j...@apache.org>
Subject [jira] Updated: (DERBY-731) org.apache.derby.impl.sql.compile.StringSlice is an inefficient way to do substring
Date Mon, 29 Jun 2009 14:43:47 GMT

     [ https://issues.apache.org/jira/browse/DERBY-731?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Dag H. Wanvik updated DERBY-731:

    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:
> 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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