Star tree mapping changes

[bharath-techie]

Description

CHANGES ARE ALREADY REVIEWED AS PART OF #14261

Created a new PR to fix unresolved conversations bug.

This PR contains the changes for star tree field mapping with feature flag protection. To make the changes extensible to other multi-field/composite/datacube type of indices in future, I've generalized the implementation under 'CompositeIndex'.

Mappings have a new section 'composite' under which multi field mappings such as 'star tree' can be defined. All the fields associated with metrics and dimensions must be present in 'properties' section. [ This is even applicable for update mapping API - but right now , its blocked for star tree - star tree can be only specified during creation of index ]

Min version :

"mappings": {
        "dynamic": "strict",
        "_source": {
            "enabled": true
        },
        "composite": {
            "startree1": {
                "type": "star_tree",
                "config": {
                    "ordered_dimensions": [
                       {
                        "name": "@timestamp"
                       },
                       {
                        "name": "status"
                       }
                    ],
                    "metrics": [
                      {
                        "name": "size"
                       },
                       {
                        "name": "request_rate"
                       }
                    ]
                }
            }
        },
        "properties": {
            "@timestamp": {
                "format": "strict_date_optional_time||epoch_second",
                "type": "date"
            },
            --------
            
        }
    }

}

And the defaults will be filled for the above fields.

NOTE : We will tune the defaults throughout the development of the star tree index.

Defaults :
Timestamp field intervals = [ Minute, Hour ]
Default Metrics for each metric field = [ SUM, COUNT, AVG, MIN, MAX ]

Complete version :

"mappings": {
        "dynamic": "strict",
        "_source": {
            "enabled": true
        },
        "composite": {
            "startree1": {
                "type": "star_tree",
                "config": {
                    "ordered_dimensions": [
                        {
                            "name": "timestamp",
                            "calendar_intervals": [
                                "day",
                                "month"
                            ]
                        },
                        {
                            "name": "size"
                        }
                    ],
                    "metrics": [
                        {
                            "name": "size",
                            "stats": [
                                "sum",
                                "avg",
                                "min"
                            ]
                        }
                    ]
                }
            }
        },
        "properties": {
            "@timestamp": {
                "format": "strict_date_optional_time||epoch_second",
                "type": "date"
            }
           -----------
        }
    }

Validations

Apart from basic validations based on user input :

- We will start with support for one field mapping under composite index , so technically one star tree index per source index.
- Maximum of 10 dimensions [will fine tune this]
- For date fields - maximum for 3 intervals
- All dimension fields and metric fields must be aggregation compatible [ doc values + field data supported ]
- We will add a limit on number of metrics later on.

Open questions

• Saw sort valiadations on 'shrink index' api etc - where I'll also add similar validations. What other index APIs we need to restrict creation / support of star tree ?

Related Issues

#13875
#14386

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❕ Gradle check result for ed03900: UNSTABLE

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Attention: Patch coverage is 75.39062% with 126 lines in your changes missing coverage. Please review.

Project coverage is 71.77%. Comparing base (a34270d) to head (ed03900).
Report is 4 commits behind head on main.

Files	Patch %	Lines
...va/org/opensearch/index/mapper/StarTreeMapper.java	81.81%	20 Missing and 8 partials ⚠️
...java/org/opensearch/index/mapper/ObjectMapper.java	56.60%	14 Missing and 9 partials ⚠️
...siteindex/datacube/startree/StarTreeValidator.java	65.78%	9 Missing and 4 partials ⚠️
...ndex/compositeindex/datacube/DimensionFactory.java	58.62%	8 Missing and 4 partials ⚠️
.../datacube/startree/StarTreeFieldConfiguration.java	72.72%	6 Missing and 3 partials ⚠️
...ompositeindex/datacube/startree/StarTreeField.java	80.00%	2 Missing and 5 partials ⚠️
...nsearch/index/mapper/CompositeMappedFieldType.java	64.70%	6 Missing ⚠️
...h/index/compositeindex/CompositeIndexSettings.java	58.33%	4 Missing and 1 partial ⚠️
.../index/compositeindex/CompositeIndexValidator.java	50.00%	3 Missing and 1 partial ⚠️
...ensearch/index/compositeindex/datacube/Metric.java	80.00%	1 Missing and 3 partials ⚠️
... and 8 more

Additional details and impacted files

@@            Coverage Diff             @@
##               main   #14605    +/-   ##
==========================================
  Coverage     71.77%   71.77%            
- Complexity    62302    62360    +58     
==========================================
  Files          5125     5140    +15     
  Lines        292473   293020   +547     
  Branches      42258    42347    +89     
==========================================
+ Hits         209912   210322   +410     
- Misses        65324    65373    +49     
- Partials      17237    17325    +88     

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[sachinpkale]

This PR is duplicate of #14261. Bypassing security check failure as it passed in original PR.

[dblock]

@bharath-techie The automatic backport has a conflict, this has not been backported, #14655.