Oracle Coherence index not working with ContainsFilter query - indexing

Question

I've added an index to a cache. The index uses a custom extractor that extends AbstractExtractor and overrides only the extract method to return a List of Strings. Then I have a ContainsFilter which uses the same custom extractor that looks for the occurence of a single String in the List of Strings. It does not look like my index is being used based on the time it takes to execute my test. What am I doing wrong? Also, is there some debugging I can switch on to see which indices are used?
public class DependencyIdExtractor extends AbstractExtractor {
/**
*
*/
private static final long serialVersionUID = 1L;
#Override
public Object extract(Object oTarget) {
if (oTarget == null) {
return null;
}
if (oTarget instanceof CacheValue) {
CacheValue cacheValue = (CacheValue)oTarget;
// returns a List of String objects
return cacheValue.getDependencyIds();
}
throw new UnsupportedOperationException();
}
}
Adding the index:
mCache = CacheFactory.getCache(pCacheName);
mCache.addIndex(new DependencyIdExtractor(), false, null);
Performing the ContainsFilter query:
public void invalidateByDependencyId(String pDependencyId) {
ContainsFilter vContainsFilter = new ContainsFilter(new DependencyIdExtractor(), pDependencyId);
#SuppressWarnings("rawtypes")
Set setKeys = mCache.keySet(vContainsFilter);
mCache.keySet().removeAll(setKeys);
}

Answer 1

I solved this by adding a hashCode and equals method implementation to the DependencyIdExtractor class. It is important that you use exactly the same value extractor when adding an index and creating your filter.
public class DependencyIdExtractor extends AbstractExtractor {
/**
*
*/
private static final long serialVersionUID = 1L;
#Override
public Object extract(Object oTarget) {
if (oTarget == null) {
return null;
}
if (oTarget instanceof CacheValue) {
CacheValue cacheValue = (CacheValue)oTarget;
return cacheValue.getDependencyIds();
}
throw new UnsupportedOperationException();
}
#Override
public int hashCode() {
return 1;
}
#Override
public boolean equals(Object obj) {
if (obj == null) {
return false;
}
if (obj instanceof DependencyIdExtractor) {
return true;
}
return false;
}
}
To debug Coherence indices/queries, you can generate an explain plan similar to database query explain plans.
http://www.oracle.com/technetwork/tutorials/tutorial-1841899.html
#SuppressWarnings("unchecked")
public void invalidateByDependencyId(String pDependencyId) {
ContainsFilter vContainsFilter = new ContainsFilter(new DependencyIdExtractor(), pDependencyId);
if (mLog.isTraceEnabled()) {
QueryRecorder agent = new QueryRecorder(RecordType.EXPLAIN);
Object resultsExplain = mCache.aggregate(vContainsFilter, agent);
mLog.trace("resultsExplain = \n" + resultsExplain + "\n");
}
#SuppressWarnings("rawtypes")
Set setKeys = mCache.keySet(vContainsFilter);
mCache.keySet().removeAll(setKeys);
}