[DERBY-3136] Cut down on object creations in LIKE clause implementation of territory based characters.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.3.2.1, 10.4.1.3
• Fix Version/s: 10.3.2.1, 10.4.1.3
• Component/s: SQL
• Assignee: Mamta A. Satoor
• Reporter: Mamta A. Satoor
• Created: 19/Oct/07 04:53
• Updated: 03/Jan/13 12:03
• Resolved: 25/Oct/07 05:50

Description

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.

Issue Links

• is related to: DERBY-2699 performance of like in territory based collation databases may be improved by changing way collation elements are calculated.
• relates to: DERBY-2698 caching collation elements in WorkHorseForCollatorDatatypes may improve performance.