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From "Mamta A. Satoor (JIRA)" <j...@apache.org>
Subject [jira] Created: (DERBY-3136) Cut down on object creations in LIKE clause implementation of territory based characters.
Date Fri, 19 Oct 2007 04:53:56 GMT
Cut down on object creations in LIKE clause implementation of territory based characters.
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                 Key: DERBY-3136
                 URL: https://issues.apache.org/jira/browse/DERBY-3136
             Project: Derby
          Issue Type: Improvement
          Components: SQL
    Affects Versions: 10.3.1.5, 10.4.0.0
            Reporter: Mamta A. Satoor


The LIKE clause for territory based characters was implemented correctly based on SQL standards
in DERBY-2967 but the object (String and CollationElementIterator) creations introduced in
DERBY-2967 can be cut down by following Knut's simple solution. I am copying that solution
from DERBY-2967. We should implement that solution to improve the performance of LIKE for
territory based characters.

**********copied from DERBY-2967**********************************************************
Another simple way to cut down the string allocations... I think you could express iapi.types.Like:checkEquality()
like this: 

    if (val[vLoc] == pat[pLoc]) { 
        // same character, so two strings consisting of this 
        // single character must be equal regardless of territory 
        return true; 
    } else if (collator == null) { 
        // not same character, must be unequal in UCS_BASIC 
        return false; 
    } 

    String s1 = new String(val, vLoc, 1); 
    String s1 = new String(pat, pLoc, 1); 

    return collator.compare(s1, s2) == 0; 

This would only allocate new objects if the characters are not equal. 
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