Hi.
This is way too slow I think since what you are explaining is something I
already tested. However I might be using the HitCollector badly.
Please prove me wrong. Supplying some code which I tested this with.
It stores a hash of the value of the term in a TIntHashSet and just
calculates the size of that set.
This one takes approx 3 sec on about 0.5M rows = way too slow.
main test class:
public class GroupingTest
{
protected static final Log log =
LogFactory.getLog(GroupingTest.class.getName());
static DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
public static void main(String[] args)
{
Utils.initLogger();
String[] fields =
{"uid","ip","date","siteId","visits","countryCode"};
try
{
IndexFactory fact = new IndexFactory();
String d = "/tmp/csvtest";
fact.initDir(d);
IndexReader reader = fact.getReader(d);
IndexSearcher searcher = fact.getSearcher(d, reader);
QueryParser parser = new MultiFieldQueryParser(fields,
fact.getAnalyzer());
Query q = parser.parse("date:20090125");
GroupingHitCollector coll = new GroupingHitCollector();
coll.setDistinct(true);
coll.setGroupField("uid");
coll.setIndexReader(reader);
long start = System.currentTimeMillis();
searcher.search(q, coll);
long stop = System.currentTimeMillis();
System.out.println("Time: " + (stop-start) + ", distinct
count(uid):"+coll.getDistinctCount() + ", count(uid): "+coll.getCount());
}
catch (Exception e)
{
log.error(e.toString(), e);
}
}
}
public class GroupingHitCollector extends HitCollector
{
protected IndexReader indexReader;
protected String groupField;
protected boolean distinct;
//protected TLongHashSet set;
protected TIntHashSet set;
protected int distinctSize;
int count = 0;
int sum = 0;
public GroupingHitCollector()
{
set = new TIntHashSet();
}
public String getGroupField()
{
return groupField;
}
public void setGroupField(String groupField)
{
this.groupField = groupField;
}
public IndexReader getIndexReader()
{
return indexReader;
}
public void setIndexReader(IndexReader indexReader)
{
this.indexReader = indexReader;
}
public boolean isDistinct()
{
return distinct;
}
public void setDistinct(boolean distinct)
{
this.distinct = distinct;
}
public void collect(int doc, float score)
{
if(distinct)
{
try
{
Document document = this.indexReader.document(doc);
if(document != null)
{
String s = document.get(groupField);
if(s != null)
{
set.add(s.hashCode());
//set.add(Crc64.generate(s));
}
}
}
catch (IOException e)
{
e.printStackTrace();
}
}
count++;
sum += doc; // use it to avoid any possibility of being optimized
away
}
public int getCount() { return count; }
public int getSum() { return sum; }
public int getDistinctCount()
{
distinctSize = set.size();
return distinctSize;
}
}
On Wed, Jan 28, 2009 at 10:51 AM, ninaS <nina...@gmx.de> wrote:
>
> By the way: if you only need to count documents (count groups) HitCollector
> is a good choice. If you only count you don't need to sort anything.
>
>
> ninaS wrote:
> >
> > Hello,
> >
> > yes I tried HitCollector but I am not satisfied with it because you can
> > not use sorting with HitCollector unless you implement a way to use
> > TopFieldTocCollector. I did not manage to do that in a performant way.
> >
> > It is easier to first do a normal search und "group by" afterwards:
> >
> > Iterate through the result documents and take one of each group. Each
> > document has a groupingKey. I remember which groupingKey is already used
> > and don't take another document of this group into the result list.
> >
> > Regards,
> > Nina
> >
>
> --
> View this message in context:
> http://www.nabble.com/Group-by-in-Lucene---tp13581760p21702742.html
> Sent from the Lucene - Java Users mailing list archive at Nabble.com.
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org
> For additional commands, e-mail: java-user-h...@lucene.apache.org
>
>
--
Marcus Herou CTO and co-founder Tailsweep AB
+46702561312
marcus.he...@tailsweep.com
http://www.tailsweep.com/
http://blogg.tailsweep.com/
