Sorting by multiple facets

[KevOrr]

Experience Report

Note: Feature requests are judged based on user experience and modeled on Go Experience Reports. These reports should focus on the problems: they should not focus on and need not propose solutions.

What you wanted to do

You can use orderasc to sort by multiple predicates, which will combine their orderings using lexicographic ordering:

{
  asdf(func: has(DOB), orderasc: DOB, orderasc: name) {
    uid
    DOB
    name
  }
}

It would be nice if we could lexicographically sort by multiple facets in the same way:

{
  asdf(func: has(edge)) {
    uid
    edge @facets(kind, index, orderasc: kind, orderasc: index) {
      uid
    }
  }
}

What you actually did

Sort by one facet, and then sort by the other on the client side, or leave unsorted and handle all sorting client-side.

Why that wasn't great, with examples

In complex, deeply nested queries, it can be cumbersome to post-process results. It divides the intended query into two steps: the actual query, and then a sorting phase. This is trickier to maintain. Besides, graphql(+-) already lends itself nicely to things such as sorting.

Any external references to support your case

https://discuss.dgraph.io/t/sorting-by-multiple-facets/4670

[campoy]

This seems like a pretty straight forward request that makes total sense.

We'll consider it for the roadmap in v1.2.

Thanks for the report, @KevOrr !

[MichelDiz]

Just a kind of "note" update on this:

After rereading this issue. I noticed that we could try another way*. However, the problem continues even after trying to reproduce. In fact the result is even worse because val(K) is in the totally wrong order.

Query

{
  F as var(func: eq(name, "Carol Lelvits")) {
    var : friend @facets(close, kind, index, K as since)
  }
    
  q(func: uid(F)) {
    uid
    friend(orderasc: val(K)) @facets(close, kind, index, since) {
      uid
      name
      val(K) # Note that the value in this variable comes in order, but the nodes themselves do not.
    }
  }
}

Result

{
  "data": {
    "q": [
      {
        "uid": "0x2711",
        "friend": [
          {
            "uid": "0x2715",
            "name": "Daryl",
            "val(K)": "2001-01-01T00:00:00Z",
            "friend|close": "true",
            "friend|index": "1",
            "friend|kind": "Childhood",
            "friend|since": "2002-01-01T00:00:00Z"
          },
          {
            "uid": "0x2712",
            "name": "Lily",
            "val(K)": "2002-01-01T00:00:00Z",
            "friend|close": "false",
            "friend|index": "2",
            "friend|kind": "School",
            "friend|since": "2011-01-01T00:00:00Z"
          },
          {
            "uid": "0x2713",
            "name": "Lucas",
            "val(K)": "2011-01-01T00:00:00Z",
            "friend|close": "false",
            "friend|index": "3",
            "friend|kind": "School",
            "friend|since": "2011-01-01T00:00:00Z"
          },
          {
            "uid": "0x2714",
            "name": "Junior",
            "val(K)": "2011-01-01T00:00:00Z",
            "friend|close": "true",
            "friend|index": "0",
            "friend|kind": "Childhood",
            "friend|since": "2001-01-01T00:00:00Z"
          }
        ]
      }
    ]
  }
}

Dataset

{
	"set": [
		{
			"name": "Carol Lelvits",
			"name|initial": "C",
			"friend": [{
					"name": "Daryl",
					"friend|close": "true",
					"friend|index": "0",
					"friend|kind": "Childhood",
					"friend|since": "2001"
				},
				{
					"name": "Lily",
					"friend|close": "true",
					"friend|index": "1",
					"friend|kind": "Childhood",
					"friend|since": "2002"
				},
				{
					"name": "Lucas",
					"friend|close": "false",
					"friend|index": "2",
					"friend|kind": "School",
					"friend|since": "2011"
				},
				{
					"name": "Junior",
					"friend|close": "false",
					"friend|index": "3",
					"friend|kind": "School",
					"friend|since": "2011"
				}

			]
		}

	]
}

[campoy]

Another user requested this via https://discuss.dgraph.io/t/do-facets-support-multi-sorting/5587/4

[ashish-goswami]

Hey @KevOrr, we have merged PR for this change in master. Please let us know you feedback.