[LUCENE-5022] Add FacetResult.mergeHierarchies

• Type: New Feature
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 4.4, 6.0
• Component/s: modules/facet
• Lucene Fields: New, Patch Available
• Assignee: Shai Erera
• Reporter: Shai Erera
• Created: 28/May/13 18:57
• Updated: 28/Aug/22 13:46
• Resolved: 29/May/13 13:10

Description

When you DrillSideways on a hierarchical dimension, and especially when you OR multiple drill-downs together, you get several FacetResults back, one for each category you drill down on. So for example, if you want to drill-down on Date/2010 OR Date/2011/May, the FacetRequests that you need to create (to get the sideways effect) are: Date/, Date/2010, Date/2011 and Date/2011/May. Date/ is because you want to get sideways counts as an alternative to Date/2010, and Date/2011 in order to get months count as an alternative to Date/2011/May.

That results in 4 FacetResult objects. Having a utility which merges all FacetResults of the same dimension into a single hierarchical one will be very useful for e.g. apps that want to display the hierarchy. I'm thinking of FacetResult.mergeHierarchies which takes a List<FacetResult> and returns the merged ones, one FacetResult per dimension.