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From "Robert Muir (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-6504) implement norms with random access API
Date Wed, 27 May 2015 14:13:17 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-6504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14561040#comment-14561040
] 

Robert Muir commented on LUCENE-6504:
-------------------------------------

{quote}
Before/now, AFAIK norms take 1 byte per field per doc of heap. I looked over the patch briefly;
does this essentially put norms off-heap?
{quote}

In the worst case. Currently they are compressed with bitpacking and other tricks to try to
be reasonable. But what was missing all along was a random access api in Directory so that
this can just be MappedByteBuffer.get(long) (see linked issue and justification). If you want
them to be in heap memory, use fileswitchdirectory and ramdirectory.

{quote}
Does this patch also bring in accurate norms or is something else required to enable actually
utilize that?
{quote}

You have 1 byte norms because your chosen similarity squashes to that, but the interface between
similarity and indexwriter is "long" since lucene 4 and all codecs test and support that.


> implement norms with random access API
> --------------------------------------
>
>                 Key: LUCENE-6504
>                 URL: https://issues.apache.org/jira/browse/LUCENE-6504
>             Project: Lucene - Core
>          Issue Type: Improvement
>            Reporter: Robert Muir
>         Attachments: LUCENE-6504.patch
>
>
> We added this api in LUCENE-5729 but we never explored implementing norms with it. These
are generally the largest consumer of heap memory and often a real hassle for users.



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