feat(trace-details): Add API endpoint & module for trace aggregations

[krsoninikhil]

Part of https://github.com/SigNoz/engineering-pod/issues/4787

Add API endpoint & module for trace aggregations. Will raise a follow up for implementation of store methods.

Query used for calculating the non-overlapping span execution time:

WITH

-- query minimum span fields
all_spans AS (
	SELECT DISTINCT ON (span_id)
		%s AS field_value,
		toUnixTimestamp64Nano(timestamp) AS start_ns,
		start_ns + duration_nano AS end_ns
	FROM %s.%s
	WHERE trace_id=? AND ts_bucket_start>=? AND ts_bucket_start<=? AND notEmpty(field_value)
	ORDER BY timestamp ASC, name ASC
),

-- calculate max end time of preceding spans
effective_start AS (
	SELECT
		field_value, end_ns,
		greatest(
			start_ns,
			ifNull(
				max(end_ns) OVER (
					PARTITION BY field_value
					ORDER BY start_ns
					ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING
				),
				toUInt64(0)
			)
		) AS effective_start_ns
	FROM all_spans
)

-- each span contributes only the tail past its effective start.
SELECT field_value, sum(toUInt64(greatest(end_ns - effective_start_ns, 0))) AS total_ns
FROM effective_start
GROUP BY field_value

Another possible option using arrayFold and arraySort simpler but hard to understand (rejected):

WITH spans AS (
    SELECT DISTINCT ON (span_id)
        <field_expr> AS grp,
        toUInt64(timestamp)                AS s,
        toUInt64(timestamp) + duration_nano AS e
    FROM signoz_traces.distributed_signoz_index_v3
    WHERE trace_id = ? AND ts_bucket_start >= ? AND ts_bucket_start <= ?
      AND notEmpty(grp)
)
SELECT
    grp,
    arrayFold(
        (acc, x) -> (
            greatest(acc.1, x.2),
            acc.2 + if(x.2 > greatest(x.1, acc.1),
                       x.2 - greatest(x.1, acc.1),
                       toUInt64(0))
        ),
        arraySort(t -> t.1, groupArray((s, e))),
        (toUInt64(0), toUInt64(0))
    ).2 AS value
FROM spans
GROUP BY grp

[krsoninikhil]

Curl example:

POST 'http://localhost:8080/api/v1/traces/fb83154a65378c5cef2bf64229d73b12/aggregations' \
  --header 'Content-Type: application/json' \
  --header 'SIGNOZ-API-KEY: <>' \
  --body '{
   "aggregations": [
        {
	     "field": {"name": "service.name", "fieldContext": "resource", "fieldDataType": "string"},  
	     "aggregation": "execution_time_percentage"
	    }
    ]
}' 

Response:

{
    "status": "success",
    "data": {
        "aggregations": [
            {
                "field": {
                    "name": "service.name",
                    "signal": "",
                    "fieldContext": "resource",
                    "fieldDataType": "string"
                },
                "aggregation": "execution_time_percentage",
                "value": {
                    "go-bulk-40": 99
                }
            }
        ]
    }
}

[therealpandey]

@krsoninikhil can we keep the aggregation response similar to QBV5?