Support Nested Aggregations as part of Star-Tree

[Shailesh-Kumar-Singh]

Description

Support Nested Aggregations as part of Star-Tree

Related Issues

Resolves #17274

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[github-actions]

❌ Gradle check result for 16f18d9: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[codecov]

Codecov Report

Attention: Patch coverage is 90.47619% with 6 lines in your changes missing coverage. Please review.

Project coverage is 72.70%. Comparing base (190ea02) to head (7fa0b16).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
...ensearch/search/startree/StarTreeQueryContext.java	76.92%	0 Missing and 3 partials ⚠️
...ket/terms/GlobalOrdinalsStringTermsAggregator.java	90.00%	1 Missing and 1 partial ⚠️
...pensearch/search/startree/StarTreeQueryHelper.java	92.85%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #18048      +/-   ##
============================================
- Coverage     72.73%   72.70%   -0.04%     
- Complexity    67933    67987      +54     
============================================
  Files          5525     5528       +3     
  Lines        312697   312847     +150     
  Branches      45379    45418      +39     
============================================
- Hits         227449   227447       -2     
- Misses        66723    66846     +123     
- Partials      18525    18554      +29     

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[Shailesh-Kumar-Singh]

it might be beneficial to run some benchmarks if using star-tree is beneficial or not

Benchmark -
(using nyc-taxis)

Keyword Terms + Keyword Terms Nested Aggregation -

{
  "size": 0,
  "aggs": {
    "by_vendor": {
      "terms": {
        "field": "rate_code_id"
      },
      "aggs": {
        "by_trip_type": {
          "terms": {
            "field": "trip_type"
          },
          "aggs": {
            "total_tips": {
              "sum": {
                "field": "tolls_amount"
              }
            }
          }
        }
      }
    }
  }
}

With Star Tree Enabled - 55 ms (First Run), 25 ms (Second Run)
Without Star Tree - 5975 ms (First Run), 4446 ms (Second Run)

Keyword + DateHistogram Nested Aggregation -

{
  "size": 0,
  "aggs": {
    "by_passenger_count": {
      "terms": {
        "field": "passenger_count"
      },
      "aggs": {
        "by_hour": {
          "date_histogram": {
            "field": "dropoff_datetime",
            "calendar_interval": "hour"
          },
          "aggs": {
            "sum_total_amount": {
              "sum": {
                "field": "total_amount"
              }
            }
          }
        }
      }
    }
  }
}

With Star Tree Enabled - 6792 ms (First Run), 6714 ms (Second Run)
Without Star Tree - 25069 ms (First Run), 24701 (Second Run)

4 LEVELS -
keyword + range(numeric) + date_histogram + value_count(numeric)

{
  "size": 0,
  "aggs": {
    "by_rate_code": {
      "terms": {
        "field": "rate_code_id"
      },
      "aggs": {
        "fare_ranges": {
          "range": {
            "field": "passenger_count",
            "ranges": [
              { "to": 5 },
              { "from": 5, "to": 20 },
              { "from": 20 }
            ]
          },
          "aggs": {
            "by_hour": {
              "date_histogram": {
                "field": "dropoff_datetime",
                "calendar_interval": "hour"
              },
              "aggs": {
                "count_trips": {
                  "value_count": {
                    "field": "trip_distance"
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}

With Star Tree Enabled - 5812 ms (First Run), 5522 ms (Second Run)
Without Star Tree - 25063 ms (First Run), 25587 (Second Run)

[expani]

We can take up the comments around design and performance post this PR.

[github-actions]

✅ Gradle check result for 61ff5f8: SUCCESS

[shwetathareja]

Helping with merge. It has already been approved by multiple folks working on Star tree feature.

[github-actions]

❌ Gradle check result for 7fa0b16: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❕ Gradle check result for 7fa0b16: 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.