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https://issues.apache.org/jira/browse/LUCENE-3584?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13169656#comment-13169656
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Yonik Seeley commented on LUCENE-3584:
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I'm traveling this week and don't have access to that box, but I should be able
to get to it next week sometime.
> bulk postings should be codec private
> -------------------------------------
>
> Key: LUCENE-3584
> URL: https://issues.apache.org/jira/browse/LUCENE-3584
> Project: Lucene - Java
> Issue Type: Task
> Reporter: Robert Muir
> Assignee: Robert Muir
> Fix For: 4.0
>
> Attachments: LUCENE-3584.patch
>
>
> In LUCENE-2723, a lot of work was done to speed up Lucene's bulk postings
> read API.
> There were some upsides:
> * you could specify things like 'i dont care about frequency data up front'.
> This made things like multitermquery->filter and other consumers that don't
> care about freqs faster. But this is unrelated to 'bulkness' and we have a
> separate patch now for this on LUCENE-2929.
> * the buffersize for standardcodec was increased to 128, increasing
> performance
> for TermQueries, but this was unrelated too.
> But there were serious downsides/nocommits:
> * the API was hairy because it tried to be 'one-size-fits-all'. This made
> consumer code crazy.
> * the API could not really be specialized to your codec: e.g. could never
> take advantage that e.g. docs and freqs are aligned.
> * the API forced codecs to implement delta encoding for things like documents
> and positions.
> But this is totally up to the codec how it wants to encode! Some codecs
> might not use delta encoding.
> * using such an API for positions was only theoretical, it would have been
> super complicated and I doubt ever
> performant or maintainable.
> * there was a regression with advance(), probably because the api forced you
> to do both a linear scan thru
> the remaining buffer, then refill...
> I think a cleaner approach is to let codecs do whatever they want to
> implement the DISI
> contract. This lets codecs have the freedom to implement whatever
> compression/buffering they want
> for the best performance, and keeps consumers simple. If a codec uses delta
> encoding, or if it wants
> to defer this to the last possible minute or do it at decode time, thats its
> own business. Maybe a codec
> doesn't want to do any buffering at all.
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