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Date: Tue, 29 Nov 2005 16:14:30 +0100 (CET)
From: "Daniel John Debrunner (JIRA)" <derby-dev@db.apache.org>
To: derby-dev@db.apache.org
Subject: [jira] Created: (DERBY-731)
 org.apache.derby.impl.sql.compile.StringSlice is an inefficient way to do
 substring
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org.apache.derby.impl.sql.compile.StringSlice is an inefficient way to do substring
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         Key: DERBY-731
         URL: http://issues.apache.org/jira/browse/DERBY-731
     Project: Derby
        Type: Improvement
  Components: SQL  
    Reporter: Daniel John Debrunner
 Assigned to: Daniel John Debrunner 
    Priority: Trivial
     Fix For: 10.2.0.0


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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