I recently tried enabling facet.method=fcs for one of my indexes and found a significant performance improvement (with a large index, many facet values, and near-realtime updates). Unfortunately, the results were also wrong. Specifically, some facet values were being partially overwritten by other facet values. (That is, if I expected facet values like "abcdef" and "123", I would get a value like "123def".)
Debugging through the code, it looks like the problem was in PerSegmentSingleValuedFaceting, specifically in the getFacetCounts method, when BytesRef val is shallow-copied from the temporary per-segment BytesRef. The byte array assigned to val is shared with the byte array for seg.tempBR, and is overwritten a few lines down by the call to seg.tenum.next().
I managed to fix it locally by replacing the shallow copy with a deep copy.
While I encountered this problem on Solr 4.2.1, I see that the code is identical in 4.5. Unless the behavior of TermsEnum.next() has changed, I believe this bug still exists.
|Transition||Time In Source Status||Execution Times||Last Executer||Last Execution Date|
|6d 13h 30m||1||Yonik Seeley||16/Oct/13 21:55|
|Status||Open [ 1 ]||Resolved [ 5 ]|
|Fix Version/s||4.5.1 [ 12325264 ]|
|Fix Version/s||4.6 [ 12325000 ]|
|Fix Version/s||5.0 [ 12321664 ]|
|Resolution||Fixed [ 1 ]|