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From "Michael McCandless (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-6645) BKD tree queries should use BitDocIdSet.Builder
Date Tue, 30 Jun 2015 19:53:04 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-6645?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14608958#comment-14608958
] 

Michael McCandless commented on LUCENE-6645:
--------------------------------------------

The lat/lons to index are here:

  http://people.apache.org/~mikemccand/latlon.subsetPlusAllLondon.txt.lzma

it uncompresses to ~1.9 GB.

Then run IndexAndSearchOpenStreetMaps.java in
luceneutil/src/main/perf.  (You have to edit the hard path to this
lat/lons input file).

Run it first with that createIndex uncommented, then comment it out
(you can just re-use that index to test searching).

When I run this on trunk I get 1.54 sec for 225 "bboxes around
London", and with the patch 3.89 seconds, or ~2.5 X slower ...


> BKD tree queries should use BitDocIdSet.Builder
> -----------------------------------------------
>
>                 Key: LUCENE-6645
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6645
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Michael McCandless
>         Attachments: LUCENE-6645.patch
>
>
> When I was iterating on BKD tree originally I remember trying to use this builder (which
makes a sparse bit set at first and then upgrades to dense if enough bits get set) and being
disappointed with its performance.
> I wound up just making a FixedBitSet every time, but this is obviously wasteful for small
queries.
> It could be the perf was poor because I was always .or'ing in DISIs that had 512 - 1024
hits each time (the size of each leaf cell in the BKD tree)?  I also had to make my own DISI
wrapper around each leaf cell... maybe that was the source of the slowness, not sure.
> I also sort of wondered whether the SmallDocSet in spatial module (backed by a SentinelIntSet)
might be faster ... though it'd need to be sorted in the and after building before returning
to Lucene.



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