Details
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New Feature
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Status: Resolved
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Major
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Resolution: Implemented
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None
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None
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None
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New, Patch Available
Description
Mike experimented with encoding just the exact categories ordinals on LUCENE-4602, and I added OrdinalPolicy.NO_PARENTS, with a comment saying that this requires a special FacetsAccumulator.
The idea is to write the exact categories only for each document, and then at search time count up the parents chain to compute requested facets (I say count, but it can be any weight).
One limitation of such accumulator is that it cannot be used when e.g. a document is associated with two categories who share the same parent, because that may result in incorrect weights computed (e.g. a document might have several Authors, and so counting the Author facet may yield wrong counts). So it can be used only when the app knows it doesn't add such facets, or that it always asks to aggregate a 'root' that in its path this criteria doesn't hold (no categories share the same parent).