V21.03: After pagination+cascade change, queries are too slow to finish

Issues Dgraph
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14

Hi Kenan,
Perhaps we can further improve on 1.38 seconds option. In the query below,

q($start: int, $end: int, $limit: int = 0) {
  var_a as var(func: eq(<qa.type>, "Device"), first: $limit) {
    var_b as <qa.has_object> @filter(eq(<qa.type>, "Object"))  (first: $limit) {
      var_c as <qa.has_indicator> @filter(eq(<qa.type>, "Indicator")) (first: $limit)
    }
  }

You can start with an Indicator type and go reverse up to Device. You can start with a smaller number of Indicator types ($limit). There are better chances of getting a couple of hits and this may improve the query performance. The query segment would look as below

q($start: int, $end: int, $limit: int = 0) {
  var_c as var(func: eq(eq(<qa.type>, "Indicator") {
    var_b as <~qa.has_indicator> @filter(eq(<qa.type>, "Object"))  (first: $limit) {
      var_a as q1<~qa.has_object> @filter()<qa.type>, "Device"), first: $limit) (first: $limit)
    }
  }

Also, thanks for the feedback you have provided. A component called Query Planner is being worked on which will address some of the suggestions you have provided.

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