Adding search processor for score normalization and combination

[martin-gaievski]

Description

Added processor that does score normalization and combination for Hybrid query results. Processor is registered via search pipeline API as search phase result processor.

In this PR we're adding support for techniques "min-max" for normalization and "arithmetic mean" for combination. Support for weights and other techniques will be added in next PRs to keep size of a single PR minimal.

Below is example of definition for registering new processor as part of search pipeline:

{
    "description": "Post processor for hybrid search",
    "phase_results_processors": [
        {
            "normalization-processor": {
                "normalization": {
                    "technique": "min_max"
                },
                "combination": {
                    "technique": "arithmetic_mean"
                }
            }
        }
    ]
}

Issues Resolved

#228, part of solution for #126

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed as per the DCO using --signoff

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[codecov]

Codecov Report

Merging #227 (e746e12) into feature/normalization (c4d0a0c) will increase coverage by 0.59%.
The diff coverage is 87.69%.

@@                     Coverage Diff                     @@
##             feature/normalization     #227      +/-   ##
===========================================================
+ Coverage                    84.95%   85.55%   +0.59%     
- Complexity                     216      296      +80     
===========================================================
  Files                           15       24       +9     
  Lines                          678      872     +194     
  Branches                       109      134      +25     
===========================================================
+ Hits                           576      746     +170     
- Misses                          60       67       +7     
- Partials                        42       59      +17     

Files Changed	Coverage Δ
...ation/ArithmeticMeanScoreCombinationTechnique.java	80.00% <80.00%> (ø)
...earch/processor/normalization/ScoreNormalizer.java	80.00% <80.00%> (ø)
...neuralsearch/processor/NormalizationProcessor.java	83.33% <83.33%> (ø)
...rmalization/MinMaxScoreNormalizationTechnique.java	84.61% <84.61%> (ø)
...arch/processor/NormalizationProcessorWorkflow.java	85.00% <85.00%> (ø)
...g/opensearch/neuralsearch/plugin/NeuralSearch.java	81.25% <87.50%> (+3.47%)	⬆️
...ralsearch/processor/combination/ScoreCombiner.java	91.83% <91.83%> (ø)
...processor/combination/ScoreCombinationFactory.java	100.00% <100.00%> (ø)
...ocessor/factory/NormalizationProcessorFactory.java	100.00% <100.00%> (ø)
...essor/normalization/ScoreNormalizationFactory.java	100.00% <100.00%> (ø)

[navneet1v]

@martin-gaievski all the comments which you have resolved please mark them as resolved.

[navneet1v]

we are not updating the shard id? why?

[martin-gaievski]

at this step we're working with a single shard results. It's the same shard id, so we need just to copy it to new results

[navneet1v]

It would be useful if you can add the comments in the code, around which operation is at shard level and what is not.

[martin-gaievski]

@martin-gaievski all the comments which you have resolved please mark them as resolved.

sure, I addressed all comments, @navneet1v please check PR again