caching collation elements in WorkHorseForCollatorDatatypes may improve
performance.
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Key: DERBY-2698
URL: https://issues.apache.org/jira/browse/DERBY-2698
Project: Derby
Issue Type: Improvement
Components: SQL
Affects Versions: 10.3.0.0
Reporter: Mike Matrigali
Priority: Minor
In
java/engine/org/apache/derby/iapi/types/WorkHorseForCollatorDatatypes.getCollationElementsForString()
an array
of int's is calculated given the string and the collator in place. If like is
ever called on the same DataValueDescriptor, caching
this calculation will be faster than redoing the calculation. To make this
change one needs to properly invalidate the cached
information when the base type value is changed. For instance in the case of
SQLChar() the following routines all result
in a change in the value of the datatype and thus need to invalidate any cached
collation element structure:
readExternalFromArray()
readExternal()
setValue()
there may be others.
DERBY-2670 is an example of what can go wrong if you get the caching wrong.
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