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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