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https://issues.apache.org/jira/browse/LUCENE-5052?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13947075#comment-13947075
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Robert Muir commented on LUCENE-5052:
-------------------------------------
{quote}
Let me ask one off-top question about switching to PulsingPF. I've heard that
it's enabled automatically for id-like field. Can you point on where it's done
particularly?
{quote}
See LUCENE-4498
if there is only one document in the postings list for a term, we just store
that document id instead of a pointer to a list ... of only one document.
The freq() for that one document is redundant as well: its the totalTermFreq()
for the term, so there is no frequency data recorded either. It still has a
pointer for positions/payload/offsets if you have that enabled: but in most
cases with an ID-like field you do not.
> 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
>
> Attachments: LUCENE-5052.patch, bitsetcodec.zip, bitsetcodec.zip
>
>
> 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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