[Xapian-devel] Integrating VSEncoding in Brass

Hurricane Tong zhangshangtong.cpp at qq.com
Wed Feb 26 15:42:42 GMT 2014


I implement a class dealing with VSEncoding and VSDecoding.
To do further test and analysis, I am trying to integrate this class into BrassPositionListTable and BrassPositionList, replacing the BitWriter and BitReader being used now. But I get confused when I meet the function
            void BrassPositionList::next_internal()
I only find the declaration of this function and can't find the implementation of this function.

As for posting list, It seems that PostlistChunkWriter directly writes the docid and the wdf, it doesn't do any encoding.
As the interpolative encoding can only be applied to an array which is ascending or decreasing, it can't be used in posting list. But VSEncoding can deal with this situation perfectly, so I think we can store a posting list of a term with the array < docid1, wdf1, docid2, wdf2, ,,,,,,, > encoded by VSEncoder. It will cost less space. But it also cost extra time to decode. Which is preferred?


Shangtong Zhang,Second Year Undergraduate,
School of Computer Science,
Fudan University, China.
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