Modern replacement needed for Index.setIndexLoadingProfileAsRetrieval()

[cmacdonald]

The method Index.setIndexLoadingProfileAsRetrieval() was always a hack.

I propose extending the IndexFactory.of() with an optional IndexProfile enum, which will hint to the Index(Loader) how it should load.

class IndexFactory {
  public Index of(IndexRef ref, IndexProfile profile);
  public Index of(IndexRef ref) { of (ref, IndexProfile.NORMAL); }
}

public enum IndexProfile {
  SMALL,
  NORMAL,
  FAST
} 

For IndexOnDisk, this will be interpreted as follows:

• SMALL: dont' preload any structures
• NORMAL: status quo, default
• FAST: pre-load all structures into memory

Per-structure configuration:

• Meta: load lookup file into memory or not (usually yes); load data file into memory or not
• Inverted: load inverted file entirely into memory or not (usually not)
• Lexicon: load entirely into memory or not (usually not)
• Document: usually loaded into memory (Should field lengths be loaded or not into memory?); Good not to load into memory, e.g. for at indexing time.

[cmacdonald]

An alternative would be an option called String[] preload, (or List preload) that specifies the structures that should be loaded into memory?

[tonellotto]

This last option could be used internally, but not exposed; avoid to give users too much rope... one simple strategy pattern is enough :-)