Lucene - Core
  1. Lucene - Core
  2. LUCENE-2335

optimization: when sorting by field, if index has one segment and field values are not needed, do not load String[] into field cache


    • Type: Improvement Improvement
    • Status: Open
    • Priority: Minor Minor
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: 4.9, master
    • Component/s: core/search
    • Labels:
    • Lucene Fields:


      Spinoff from java-dev thread "Sorting with little memory: A suggestion", started by Toke Eskildsen.

      When sorting by SortField.STRING we currently ask FieldCache for a StringIndex on that field.

      This can consumes tons of RAM, when the values are mostly unique (eg a title field), as it populates both int[] ords as well as String[] values.

      But, if the index is only one segment, and the search sets fillFields=false, we don't need the String[] values, just the int[] ords. If the app needs to show the fields it can pull them (for the 1 page) from stored fields.

      This can be a potent optimization – alot of RAM saved – for optimized indexes.

      When fixing this we must take care to share the int[] ords if some queries do fillFields=true and some =false... ie, FieldCache will be called twice and it should share the int[] ords across those invocations.


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          • Assignee:
            Michael McCandless
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