SloppyMath is too accurate [LUCENE-7124]
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- Java
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Description
Followup from #8178:
Latitude/longitude values are encoded by GeoPointField/LatLonPoint with 1E-6 or 1E-7 error.
However, the sloppy distance formula is far too accurate to the actual (10nm), making it slower and relying on large tables. We should only do as good as we need, and especially try to reduce the huge tables.
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Migrated from [LUCENE-7124](https://issues.apache.org/jira/browse/LUCENE-7124) by Robert Muir (@rmuir), updated Mar 22 2016
Attachments: [LUCENE-7124.patch](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-7124/LUCENE-7124.patch)
Contributor guide
Research direction
Read the GeoPointField and LatLonPoint implementations and the LUCENE-7124.patch attachment first. Compare the sloppy distance formula's accuracy with the encoding error, then investigate how its large tables affect performance. Done means achieving only the accuracy required by the encoded coordinates while reducing the table footprint without changing expected distance behavior.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- java
- Domain
- search
- Issue type
- Refactor
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100