[Epic] Explain Request Functionality

[jsimnz]

Simple Explain SUB-TASKS (initial implementation will be verbose = true).

• [x] Explain selectNode
• [x] Explain selectTopNode
• [x] Explain createNode
• [x] Explain deleteNode

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Debug Explain SUB-TASKS

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Prediction Explain SUB-TASKS

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Execution Explain SUB-TASKS

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Bugs:

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CHECKLIST:

• [x] Update schema to parse in @explain directive from the query and mutation location only.
• [x] Iterate over all directive and find the matching explain.
• [ ] Introduce the option to set verbose false for explain request.
• [ ] Make sure to test MultiNode properly.

DESCOPED:

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DESCRIPTION

Implement an Explain API + Endpoint for returning the structure of a plan graph as generated by the planner package.

Request:

query @explain {
  user {
    _key
    age
    name
  }
}

Response:

{
  "data": [
    {
      "explain": {
        "selectTopNode": {
          "selectNode": {
            "filter": null,
            "scanNode": {
              "collectionID": "1",
              "collectionName": "user",
              "filter": null
            }
          }
        }
      }
    }
  ]
}

There should be additional data options. Such as ANALYZE (from SQL) which would actually execute the Request, and provide insights into perf analysis on a per node basis and EXECUTE to provide insights to what was actually executed.

There should be an additional option to change the verbosity level of explain to omit attributes like filter when they are null.

Output is only going to be in JSON.

[jsimnz]

https://github.com/sourcenetwork/defradb/blob/c1133123f1043229d9d645dfb3baff0950b24825/api/http/api.go#L1

[shahzadlone]

So pretty much like this example:

from: https://github.com/cockroachdb/cockroach/blob/master/docs/tech-notes/life_of_a_query.md

[jsimnz]

Spec doc: https://hackmd.io/BbMstl-9TE6n_Nq-5G8PRw?view