Hi Rob,
Thanks a lot for above very descriptive answer. I will give it a try.
On Friday, March 18, 2016, Rob Audenaerde <rob.audenae...@gmail.com> wrote:
> Hi Gimantha,
>
> You don't need to store the aggregates and don't need to retrieve
> Documents. The aggregates are calculated during collection using the
> BinaryDocValues from the facet-module. What I do, is that I need to store
> values in the facets using AssociationFacetFields. (for example
> FloatAssociationFacetField). I just choose facets because then I can use
> the facets as well :)
>
> I have a implementation of `Facets` class that does all the aggregation. I
> cannot paste all the code unfortunately, but here is the idea (it is loosly
> based on the TaxonomyFacetSumIntAssociations implementation, where you can
> look up how the BinaryDocValues are translated to ordinals and to facets).
> This aggregation is used in conjunction with a FacetsCollector, which
> collects the facets during a search:
>
> FacetsCollector fc = new FacetsCollector();
> searcher.search(new ConstantScoreQuery(query), fc);
>
>
> Then, the use this FacetsCollector:
>
> taxoReader = getTaxonomyReaderManager().acquire();
> OnePassTaxonomyFacets facets = new OnePassTaxonomyFacets(taxoReader,
> LuceneIndexConfig.facetConfig);
> Collection<GroupByResultTuple>
> facets.aggregateValues(fc.getMatchingDocs(), p.getGroupByListWithoutData(),
> aggregateFields);
>
>
> The aggregateValues method (cannot paste it all :( ) :
>
>
> public final Collection<GroupByResultTuple>
> aggregateValues(List<MatchingDocs> matchingDocs, final List<GroupByField>
> groupByFields,
> final List<String> aggregateFieldNames, EmptyValues
> emptyValues) throws IOException {
> LOG.info("Starting aggregation for pivot.. EmptyValues=" +
> emptyValues);
>
> //We want to group a list of ordinals to a list of aggregates. The
> taxoReader has the ordinals, so a selection like 'Lang=NL, Region=South'
> will
> //end up like a MultiIntKey of [13,44]
> Map<MultiIntKey, List<TotalFacetAgg>> aggs = Maps.newHashMap();
>
> List<String> groupByFieldsNames = Lists.newArrayList();
> for (GroupByField gbf : groupByFields) {
> groupByFieldsNames.add(gbf.getField().getName());
> }
> int groupByCount = groupByFieldsNames.size();
>
> //We need to know which ordinals are the 'group-by' ordinals, so
> we can check if a ordinal that is found, belongs to one of these fields
> int[] groupByOrdinals = new int[groupByCount];
> for (int i = 0; i < groupByOrdinals.length; i++) {
> groupByOrdinals[i] =
> this.getOrdinalForListItem(groupByFieldsNames, i);
> }
>
> //We need to know with ordinals are the 'aggregate-field'
> ordinals, so we can check if a ordinal that is found, belongs to one of
> these fields
> int[] aggregateOrdinals = new int[aggregateFieldNames.size()];
> for (int i = 0; i < aggregateOrdinals.length; i++) {
> aggregateOrdinals[i] =
> this.getOrdinalForListItem(aggregateFieldNames, i);
> }
>
> //Now we go and find all the ordinals in the matching documents.
> //For each ordinal, we check if it is a groupBy-ordinal, or a
> aggregate-ordinal, and act accordinly.
> for (MatchingDocs hitList : matchingDocs) {
> BinaryDocValues dv =
> hitList.context.reader().getBinaryDocValues(this.indexFieldName);
>
> //Here find the oridinals of the group-by-fields and the
> arrgegate fields.
> //Create a multi ordinal key MultiIntKey from the
> group-by-ordinals and use that to add the current value of the fiels to do
> the agggregation to the facet-aggregates
>
> ......
>
>
> Hope this helps :)
> -Rob
>
>
--
Gimantha Bandara
Software Engineer
WSO2. Inc : http://wso2.com
Mobile : +94714961919
