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From "Dyre Tjeldvoll (JIRA)" <derby-...@db.apache.org>
Subject [jira] Updated: (DERBY-731) org.apache.derby.impl.sql.compile.StringSlice is an inefficient way to do substring
Date Mon, 19 Dec 2005 17:11:31 GMT
     [ http://issues.apache.org/jira/browse/DERBY-731?page=all ]

Dyre Tjeldvoll updated DERBY-731:
---------------------------------

    Component: Performance

Added performance as a component


> org.apache.derby.impl.sql.compile.StringSlice is an inefficient way to do substring
> -----------------------------------------------------------------------------------
>
>          Key: DERBY-731
>          URL: http://issues.apache.org/jira/browse/DERBY-731
>      Project: Derby
>         Type: Improvement
>   Components: SQL, Performance
>     Reporter: Daniel John Debrunner
>     Assignee: 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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