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From "Robert Muir (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (LUCENE-7179) GeoPoint and LatLonPoint test data should quantize once
Date Tue, 05 Apr 2016 18:10:25 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-7179?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15226801#comment-15226801
] 

Robert Muir commented on LUCENE-7179:
-------------------------------------

{quote}
But you have to remember that GeoPointField works by way of a quad tree represented in unsigned
long space. This isn't "quantization" for memory/disk purposes, its a dimensionality reduction
technique. 
{quote}

This is unrelated to what I am talking about. I am only talking about the truncation of the
data provided by the user. 

All encoding around this stuff needs to be stable: I think I cannot compromise on this! we
can encode/decode 1 time or 10,000 times and expect the same result. If we don't handle the
rounding issues and overflow issues, then encoded integers aren't sorted in a meaningful way
in integer or binary space, which means things are buggy. 

> GeoPoint and LatLonPoint test data should quantize once
> -------------------------------------------------------
>
>                 Key: LUCENE-7179
>                 URL: https://issues.apache.org/jira/browse/LUCENE-7179
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Nicholas Knize
>         Attachments: LUCENE-7179.patch
>
>
> {{LatLonPoint}} and {{GeoPointField}} tests pre quantizes test data to ensure consistency
with indexed (encoded) data. The pre quantized data then becomes indexed, undergoing another
quantization. To guarantee numerical stability this should be changed such that the test data
is quantized after indexing.



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