private ReadResult Reduce(IDictionary <long, SortedList <long, byte> > query, ReadSession readSession, int skip, int take)
{
IDictionary <long, BOCHit> scored = new Dictionary <long, BOCHit>();
foreach (var term in query)
{
var hit = Scan(term.Key, term.Value);
BOCHit score;
if (scored.TryGetValue(hit.PostingsOffsets.PostingsOffset, out score))
{
scored[hit.Key].Score = score.Score + hit.Value.Score;
}
else
{
scored.Add(hit.Key, hit.Value);
}
}
var sortedHits = scored.Values.OrderByDescending(h => h.Score);
var offsets = sortedHits.Select(h => h.PostingsOffset).ToArray();
var docIds = _postingsReader.Read(skip, take, offsets);
var window = docIds.GroupBy(x => x).Select(x => (x.Key, x.Count()))
.OrderByDescending(x => x.Item2)
.Skip(skip)
.Take(take)
.Select(x => x.Key).ToList();
var docs = readSession.ReadDocs(window);
return(new ReadResult {
Docs = docs, Total = docIds.Count
});
}
private async Task <IDictionary <ulong, float> > DoRead(Query query)
{
try
{
IDictionary <ulong, float> result = null;
var cursor = query;
while (cursor != null)
{
var keyHash = cursor.Term.Key.ToString().ToHash();
var ix = GetIndex(keyHash);
if (ix != null)
{
var queryTerm = new VectorNode(cursor.Term.Value.ToString());
var match = ix.ClosestMatch(queryTerm);
if (match.Score > 0)
{
if (match.Node.PostingsOffset < 0)
{
throw new InvalidDataException();
}
var docIds = (await _postingsReader.Read(CollectionId, match.Node.PostingsOffset))
.ToDictionary(x => x, y => match.Score);
if (result == null)
{
result = docIds;
}
else
{
if (cursor.And)
{
var aggregatedResult = new Dictionary <ulong, float>();
foreach (var doc in result)
{
float score;
if (docIds.TryGetValue(doc.Key, out score))
{
aggregatedResult[doc.Key] = score + doc.Value;
}
}
result = aggregatedResult;
}
else if (cursor.Not)
{
foreach (var id in docIds.Keys)
{
result.Remove(id);
}
}
else // Or
{
foreach (var id in docIds)
{
float score;
if (result.TryGetValue(id.Key, out score))
{
result[id.Key] = score + id.Value;
}
else
{
result.Add(id.Key, id.Value);
}
}
}
}
}
}
cursor = cursor.Next;
}
_log.Log("query {0} matched {1} docs", query.Term, result == null ? 0 : result.Count);
return(result);
}
catch (Exception ex)
{
_log.Log(ex);
throw;
}
}