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https://issues.apache.org/jira/browse/LUCENE-5052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13681049#comment-13681049
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Stefan Pohl commented on LUCENE-5052:
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The following paper might be informative in regard to this ticket (you can even
go beyond maxdocs/8, if compared against VInt-coding):
A. Moffat and J. S. Culpepper. Hybrid Bitvector Index Compression. In
Proceedings of the 12th Australasian Document Computing Symposium (ADCS 2007),
December 2007. pp 25-37.
available from: http://goanna.cs.rmit.edu.au/~e76763/publications.html
More generally, it would be nice to determine the PostingsListFormat depending
on statistics of individual terms, not only per-field.
> bitset codec for off heap filters
> ---------------------------------
>
> Key: LUCENE-5052
> URL: https://issues.apache.org/jira/browse/LUCENE-5052
> Project: Lucene - Core
> Issue Type: New Feature
> Components: core/codecs
> Reporter: Mikhail Khludnev
> Labels: features
> Fix For: 5.0
>
>
> Colleagues,
> When we filter we don’t care any of scoring factors i.e. norms, positions,
> tf, but it should be fast. The obvious way to handle this is to decode
> postings list and cache it in heap (CachingWrappingFilter, Solr’s DocSet).
> Both of consuming a heap and decoding as well are expensive.
> Let’s write a posting list as a bitset, if df is greater than segment's
> maxdocs/8 (what about skiplists? and overall performance?).
> Beside of the codec implementation, the trickiest part to me is to design API
> for this. How we can let the app know that a term query don’t need to be
> cached in heap, but can be held as an mmaped bitset?
> WDYT?
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